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FEKO Examples Guide - the Academic Training Center

1. A 8 1 A 9 1 dipole sci dcndediecwdeeewiadeediedegnes A 1 1 A 7 1 POT KOC ss dace sitse einean EER H 1 1 ideal lumped element matching E 3 1 near a cube eee eee eee eee A 2 1 near a dielectric sphere F 1 1 near a large metal plate A 3 1 E CASE port sn ocde hiieaduwantyisndtiewiedesas A 9 1 electrically large model B 1 1 B 2 1 B 3 1 H 2 1 EMG ji cct ented bodes podee nenii D 1 1 D 2 1 D 3 1 excitation edge excitation 4 E 1 1 E 5 1 FEM current source 06 A 12 1 FEM modal source 000 ees A 12 1 impressed field distribution A 11 1 microstrip feed cece eee ee A 9 1 PIN PEC 2 cede errs Powe dune edetew ewes A 11 1 plane wave C 1 1 C 2 1 C 3 1 C 4 1 D 1 1 D 3 1 H 2 1 radiation pattern point source A 13 1 B 3 1 voltage on an edge 0 200s A 9 1 voltage source 06 A 16 1 A 17 1 waveguide feed A 11 1 E 2 1 exposure analysis e cece e ee eee F 1 1 F far field A 1 1 A 3 1 A 4 1 A 7 1 A 11 1 A 12 1 A 16 1 A 17 1 far field data file 8 B 2 1 B 3 1 FDTD oetuseic et oietetaedes A 3 1 A 8 1 E 5 1 feed NEtWOrk viwiat Mises dtaset tase terei teias E 4 1 FEM current source e eee e eee A 12 1 FEM modal source A 12 1 A 12 3 FEM MoM hybrid 0 ceeee cues
2. E 3 1 E 4 Subdividing a model using non radiating networks E 4 1 E S A Microstrip coupler se cw kee Av RRR ARE TRH HES HH REHS EOE OS E 5 1 F Bio electromagnetics F 1 Exposure of muscle tissue using MoM FEM hybrid F 1 1 F 2 Magnetic Resonance Imaging MRI birdcage head coil example F 2 1 G Time domain examples G 1 Time analysis of the effect of an incident plane wave on an obstacle G 1 1 H Special solution methods H 1 A Forked dipole antenna continuous frequency range H 1 1 H 2 Using the MLFMM for electrically large models 4 H 2 1 H 3 Horn feeding a large reflector 0 cece eee eee ees H 3 1 H 4 Optimise waveguide pin feed location 20 002 e eee H 4 1 I User interface tools I 1 POSTFEKO Application automation 666456 e bd ee ees thee a eiws I 1 1 J Index Ne AEE E E EE EEE E E E E E E E E E EE E E E I 1 May 2014 FEKO Examples Guide INTRODUCTION 1 Introduction This Examples guide presents a set of simple examples which demonstrate a selection of the features of the FEKO Suite The examples have been selected to illustrate the features without being unnecessarily complex or requiring excessive run times The input files for the examples can be found in the examples ExampleGuide_models directory under the FEKO installation No results are provided for these examples and in most cases the pre c
3. May 2014 FEKO Examples Guide FINITE ARRAY WITH NON LINEAR ELEMENT SPACING A 17 3 Meshing Use Standard meshing to mesh the geometry Set the segment radius to wireRadius Requests Request a 3D far field that covers the top half space A sampling increment of 0 1 5 and go 1 5 is needed to obtain a reasonable resolution Set the origin of the far field Workplane tab to 1 5 1am0 for both the Xand the Y components This does not change the far field pattern this will affect the phase but places the display of the far field on the 3D view in the middle of the patch array Note that a warning may be encountered when running the solution This is because losses cannot be calculated in an infinitely large medium as is required for the extraction of antenna directivity information gain is computed by default This warning can be avoided by ensuring that the far field gain be calculated instead of the directivity This is set on the advanced tab of the far field request in the tree A 17 2 Results Figure A 17 3 shows the comparison of two theta cuts of the array approximation with the results obtained using an equivalent full MoM model The results compare favourably Gain Phi 0 Full Phi 0 Array Phi 90 Full Phi 90 Array Figure A 17 3 The far field gain pattern for the array Apart from the relative ease of construction when using arrays there is also a performance im provement when
4. FEK Comprehensive Electromagnetic Solutions A FEKO Examples Guide Suite 7 0 May 2014 Copyright 1998 2014 EM Software amp Systems S A Pty Ltd 32 Techno Avenue Technopark Stellenbosch 7600 South Africa ir Tel 27 21 831 1500 Fax 27 21 880 1936 SMSS E Mail feko emss co za J WWW www feko info CONTENTS i Contents Introduction sss esd dow wow Puck eua whe dw le Be Sow Sw Be Soe we ee RE we BEE ai 1 A Antenna synthesis analysis Al Te BN ox aerae SER Ae ee ew ee ee E A 1 1 Az Dip leinfrontofa dibe as oe hs RSH SEP EOE SEES HORS A 2 1 A 3 Dipole in front ofa plate 1 0 ce ee ee ees A 3 1 A 4 A monopole antenna on a finite ground plane A 4 1 A 5 Yagi Uda antenna above areal ground 2 00000 A 5 1 A 6 Pattern optimisation of a Yagi Uda antenna 20000 A 6 1 for Tee pene oe sh dae eae hoo Se hE RS OER SE RRS A 7 1 A 8 Microstrip patch antenna 66 cw es ee ee ee he OEE EO aS A 8 1 A 9 Proximity coupled patch antenna with microstrip feed A 9 1 A 10 Modelling an aperture coupled patch antenna A 10 1 A 11 Different ways to feed a horn antenna 0 2c e ee eeee A 11 1 A 12 Dielectric resonator antenna on finite ground 4 4 A 12 1 A 13 A lens antenna with geometrical optics GO ray launching A 13 1 A 14 Windscreen antenna on an automobile 4 64 66 6984s eeu
5. e Define the following variables r0 1 Radius of sphere r1 1 2 Radius of FEM vacuum sphere f_min 1e6 Lower operating frequency f_max 100e6 Upper operating frequency d 2 5e 9 Thickness of the shell e Silver is a predefined metallic medium in the media library Add the medium to the model e Create a new dielectric medium with the default properties of free space Label the medium air e Create a sphere at the origin with radius equal to the defined variable ro e Create another sphere at the origin with radius equal to the defined variable r1 e Set the region of both spheres to air A dielectric material is used with the properties of free space instead of using the free space medium directly to ensure that the region is meshed as a tetrahedral volume for the FEM May 2014 FEKO Examples Guide SHIELDING FACTOR OF A SPHERE WITH FINITE CONDUCTIVITY D 1 3 e Set the medium type of the inner sphere s face to silver and set the thickness equal to the variable d e Union the two spheres e Set the solution method for the regions to FEM finite element method e Create a single incident plane wave with direction set to 0 90 and 180 e Set the frequency to calculate a continuous range between f_min and f_max Requesting calculations In the X 0 plane use geometric symmetry In the Y 0 use magnetic symmetry and in the Z 0 plane use electric symmetry The solution request
6. 2 d 2 d 0 e End 2 d 2 d 0 e Request 31 field points in both directions Meshing information Use the Coarse auto mesh setting CEM validate After the model has been meshed run CEM validate Take note of any warnings and errors Correct any errors before running the FEKO solution kernel G 1 2 POSTFEKO The currents and fields on and around the obstacle have been calculated within a predetermined frequency range Any time signal whose spectral content falls within this band may be used to analyse the time response of the system To illustrate this the effect of the two signals depicted in figure G 1 2 will be analysed Time signals Gaussian pulse Triangular pulse Amplitude 0 10 20 30 40 50 60 70 80 90 100 Time ns Figure G 1 2 Input time signals The parameters required to define the input time signals are provided in Table G 1 1 May 2014 FEKO Examples Guide TIME ANALYSIS OF THE EFFECT OF AN INCIDENT PLANE WAVE ON AN OBSTACLE Property Gaussian pulse Triangular pulse Time axis unit ns ns Total signal duration 100 100 Amplitude 1 1 Pulse delay 19 19 Pulse width 4 8 Number of samples 400 400 Table G 1 1 Input time signal properties G 1 3 Results The 3D view image depicted in figure G 1 1 shows the response of the near field and currents when the triangular pulse is applied to the system Animating over time is a useful m
7. 2230 Length of one arm of the first director in wavelengths 2230 Length of one arm of the second director in wavelengths 3 Spacing between the reflector and driven element in wavelengths 3 Spacing between the driven element and the first director in wavelengths 0 1e 3 Spacing between the two directors in wavelengths 4 Radius of the elements e Create the active element of the Yagi Uda antenna Set the start point as 0 0 L1 lambda and the end point as 0 0 L1 lambda e Add a port on a segment in the centre of the wire e Add a voltage source on the port 1 V 0 50 Q May 2014 FEKO Examples Guide PATTERN OPTIMISATION OF A YAGI UDA ANTENNA A 6 2 e Set the incident power for a 50 transmission line to 1 W e Create the wire for the reflector Set the start point as SO lambda 0 LO lambda and the end point as SO lambda 0 LO lambda e Create the two directors Set the start point and end point for director1 as the following S1 lambda 0 L2 lambda and Si lambda 0 L2 lambda respectively For director2 set the start point as S1 S2 lambda 0 L3 lambda and the end point S1 S2 lambda 0 L3 lambda e Set the frequency to freq Requesting calculations The Z 0 plane is an electric plane of symmetry A magnetic plane of symmetry exists in the Y 0 plane but since all the wires are in the Y 0 plane adding the magnetic symmetry setti
8. A 15 2 Results Characteristic modes are the basic building blocks for many electromagnetic results When ex citations and loads are added to a solution we unknowingly calculate a weighted sum of the various characteristic modes The following results will show that if the characteristic modes are properly understood then one can alter the behaviour of a structure without making any changes to the geometry Note that when comparing the characteristic modes to the reconstructed modes all values need to be normalised May 2014 FEKO Examples Guide DESIGN OF A MIMO ELLIPTICAL RING ANTENNA CHARACTERISTIC MODES A 15 4 h C he O Figure A 15 3 MIMO ring s first characteristic current mode left vs the reconstructed mode right Mode 1 comparison Figure A 15 3 shows how the first characteristic mode left can be recreated when sources are placed in the appropriate locations Mode 5 comparison Figure A 15 4 shows how the fifth characteristic mode left can be recreated when sources are placed in the appropriate locations O O Figure A 15 4 MIMO ring s fifth characteristic current mode left vs the reconstructed mode right Electric far fields Figure A 15 5 shows how the manually electric fields compare to the characteristic field modes that were calculated using the characteristic modes Note that due to the lack of excitations when using characteristic modes that the results are normalised in th
9. Far field No Ground Real Ground Real Ground Optimised Figure A 5 2 The directivity pattern of the Yagi Uda antenna over a real ground and without any ground Note that the optimised pattern is also shown May 2014 FEKO Examples Guide PATTERN OPTIMISATION OF A YAGI UDA ANTENNA A 6 1 A 6 Pattern optimisation of a Yagi Uda antenna Keywords antenna Yagi Uda radiation pattern optimisation In this example we consider the optimisation of a Yagi Uda antenna consisting of a dipole a reflector and two directors to achieve a specific radiation pattern and gain requirement The frequency is 1 GHz The antenna has been roughly designed from basic formulae but we would like to optimise the antenna radiation pattern such that the gain is above 8 dB in the main lobe 30 lt lt 30 and below 7 dB in the back lobe 90 lt lt 270 Portl source Figure A 6 1 A 3D view of the Yagi Uda antenna A 6 1 The antenna Creating the model The steps for setting up the model are as follows e Define the following variables physical dimensions based on initial rough design fr eq lambda LO Li L2 L3 SO Si S2 r O O O O O O 1e9 The operating frequency c0 freq The wavelength in free space at the operating frequency 2375 Length of one arm of the reflector element in wavelengths 2265 Length of one arm of the driven element in wavelengths
10. fmin 0 4e9 The minimum simulation frequency fmax 1 5e9 The maximum simulation frequency lambda c0 freq The wavelength in free space at the operating frequency LO 0 2375 Length of one arm of the reflector element in wavelengths May 2014 FEKO Examples Guide ANTENNA RADIATION HAZARD RADHAZ SAFETY ZONES D 4 2 L1 0 2265 Length of one arm of the driven element in wavelengths L2 0 2230 Length of one arm of the first director in wavelengths L3 0 2230 Length of one arm of the second director in wavelengths SO 0 3 Spacing between the reflector and driven element in wavelengths S1 0 3 Spacing between the driven element and the first director in wavelengths 2 0 3 Spacing between the two directors in wavelengths r 0 1e 3 Radius of the elements e Create the active element of the antenna Set the Start point as 0 0 L1 lambda and the End point as 0 0 L1 lambda e Add a port in the centre of the wire e Add a voltage source on the port 1 V 0 50 Q e Set the incident power for a 50 transmission line to 25 W e Create the wire for the reflector Set the Start point as SO lambda 0 LO lambda and the End point as SO lambda 0 LO lambda e Create the two directors Set the Start point and End point for Director1 as the following S1 lambda 0 L2 lambda and S1 lambda 0 L2 lambda respectively For Director2 se
11. After the model has been meshed run CEM validate Take note of any warnings notes and errors Please correct error before running the FEKO solution kernel H 2 2 Results The runtime and memory that was used for both the MoM and MLFMM models are given in Table H 2 1 As the problem size increases the difference will become more and more significant Memory and other detailed information is available in the out file as well as in POSTFEKO s Details Browser Solution method Memory MBytes Runtime seconds MoM 487 146 MLFMM 165 53 Table H 2 1 Memory and runtime requirements for the Mom and MLFMM models Figure H 2 2 compares the results obtained with the MLFMM with those obtained with the MoM May 2014 FEKO Examples Guide USING THE MLFMM FOR ELECTRICALLY LARGE MODELS H 2 3 Radar cross section RCS 0 MoM e MLFMM Figure H 2 2 Bistatic RCS of a trihedral Comparison of the MLFMM and MoM results May 2014 FEKO Examples Guide HORN FEEDING A LARGE REFLECTOR H 3 1 H 3 Horn feeding a large reflector Keywords Waveguide horn reflector PO MLFMM aperture source spherical mode source equivalent source decouple far field A cylindrical horn is excited with a waveguide port is used to feed a parabolic reflector at 12 5 GHz The reflector is electrically large diameter of 36 wavelengths and well separated from the horn An illustration of the model is sho
12. May 2014 FEKO Examples Guide DIFFERENT WAYS TO FEED A HORN ANTENNA A 11 5 These files are then used as the input source for the aperture feed horn model For more details on how the fields are calculated see Create_Mode_Distribution_cf cfx To add the aperture excitation to the model create an aperture feed source by clicking on the Aperture field source button and using the following properties e The electric field file is stored as Create_Mode_Distribution_cf efe e The magnetic field file is stored as Create_Mode_Distribution_cf hfe e Uncheck the Also sample along edges check box e The width of the aperture is wa e The height of the aperture is wb e The number of points along X U is 10 e The number of points along Y V is 5 e Set the Workplane origin to wa 2 wb 2 wl lambda 4 Note that electric symmetry may be used in the Y 0 plane as well as magnetic symmetry in the X 0 plane This is only valid when the aperture excitations also conform to this symmetry A 11 4 FEM modal port Creating the model The steps for setting up the model are as follows e Create a new model e Set the model unit to centimetres e Create the same variables as for the wire model in section A 11 1 e Create a dielectric labelled air with the default dielectric properties of free space e Create the waveguide section using a cuboid primitive and the Base corner width depth height definition method The Base corner is at wa 2
13. a 5 Su FDTD 25 Sz measured 30 Ss measured Sy measured 35 m_m SN 2 5 3 0 3 5 4 0 4 5 5 0 Frequency GHz Figure E 5 2 Coupling to microstrip coupler ports May 2014 FEKO Examples Guide Chapter F Bio electromagnetics EXPOSURE OF MUSCLE TISSUE USING MOM FEM HYBRID F 1 1 F 1 Exposure of muscle tissue using MoM FEM hybrid Keywords exposure analysis FEM MoM hybrid method SAR dielectric losses This example considers the exposure of a sphere of muscle tissue to the field created by a dipole antenna between 0 1 1 GHz The geometry of the example is shown in Figure F 1 1 Figure F 1 1 Sphere of muscle tissue illuminated by a dipole antenna F 1 1 Dipole and muscle tissue Note There is an air layer used around the sphere of muscle tissue to reduce the number of triangle elements required on the boundary between the FEM and MoM regions This is not strictly necessary but if this method is not used the resource requirements for the computation of the interaction between the FEM and the MoM regions would be higher without an improvement in the accuracy of the results Creating the model The steps for setting up the model are as follows e Define the following variables f_min 100e6 Minimum simulation frequency freq 900e6 Operating frequency f_max 1e9 Maximum simulation frequency d 0 1 Distance between the dipole and
14. in 0 5 increments 0 lt lt 180 in 5 increments This is the default set of values when 3D pattern is selected on the dialog On the Advanced tab enable the option to Calculate continuous far field data and also Calculate spherical expansion mode coefficients This file will be stored with a sph extension Create a spherical near field request with its origin at w_1 0 0 radius of 1 3 w_1 0 lt 0 lt 180 0 lt lt 360 and an increment of 5 for 0 and Change the check box setting so that the near field is not sampled on the edges Sampling on the edges would create duplicate request points at 0 and 360 and also at the poles of the spherical coordinate system Ensure that the Export fields to ASCII file is checked on the Advanced tab of the Near field request dialog this saves the electric near fields to a efe file and the magnetic near fields to a hfe file Meshing has already been set up and nothing should be changed Save the file and run the solver Once the simulation has completed the model containing on the reflector can be constructed H 3 5 Aperture excitation and LE PO reflector The steps for setting up the model containing the reflector and equivalent aperture source are as follows e Open the original model and save it under a new name e Remove the waveguide excitation and port e Remove the horn from the model e Create a new aperture excitation Set the position of the workplane equal to
15. lt 90 and p 0 with 0 in 10 steps Set the polarisation angle equal to 90 e Set the frequency equal to freq e Activate HOBF for the model Click on the Solver settings button Solve Run tab On the General tab check the Solve with higher order basis functions HOBF check box Ensure the basis function order is set to auto May 2014 FEKO Examples Guide A MAGNETIC FIELD PROBE D 3 2 Requesting calculations Since all E fields will be normal to the Y 0 plane at Y 0 a single plane of electric symmetry is defined on this plane The solution requests are e Add a request to store all wire currents Meshing information Use the fine or standard auto meshing setting with the wire segment radius equal to wireRad The user is encouraged to play around with the mesh settings on the Advanced tab of the mesh dialog CEM validate After the model has been meshed run CEM validate Take note of any warnings and errors Correct any errors before running the FEKO solution kernel D 3 2 Results The current induced in a specific segment on the probe is shown versus solution number in Figure D 3 2 This is plotted on a currents and charges graph Each solution represents a different plane wave excitation direction starting at 92 0 in steps of 10 to 0 90 for 0 May 2014 FEKO Examples Guide A MAGNETIC FIELD PROBE D 3 3 Currents through segment 1 7 14 7 11 7 08 7 05 Current mA 7 02 6
16. nfPt efieldcomp3 nfPt efieldcomp3 EfieldLimit SCALE THE MAGNETIC FIELD VALUES Scale the values to indicate percentages The percentage represents the field value relative to the limit of the standard nfPt hfieldcomp1 nfPt hfieldcomp1 HfieldLimit nfPt hfieldcomp2 nfPt hfieldcomp2 HfieldLimit nfPt hfieldcomp3 nfPt hfieldcomp3 HfieldLimit end pf DataSet ForAllValues calculateRADHAZThresholds nf Note that in essence the values being returned are no longer near fields As such interpret them carefully in POSTFEKO return nf May 2014 FEKO Examples Guide Chapter E Waveguide microwave circuits A MICROSTRIP FILTER E 1 1 E 1 A Microstrip filter Keywords microstrip filter FEM SEP input impedance microstrip excitation FEM current source edge excitation reflection coefficient S parameters planar multilayer substrate A simple microstrip notch filter is modelled The filter is solved using several different techniques the surface equivalence principle SEP the finite element method FEM and on an infinite sub strate using a planar multilayer substrate modelled with Green s functions The reference for this example may be found in G V Eleftheriades and J R Mosig On the Network Characterization of Planar Passive Circuits Using the Method of Moments IEEE Trans MTT vol 44 no 3 March 1996 pp 438 445 Figs 7 and 9 The geometry of the finite sub
17. the remaining face of the half sphere These should be the default medium e Use the simplify transform to remove redundant faces and edges in the model e Add a waveguide port to the dielectric face of FeedBase at the bottom of the antenna e Apply waveguide excitation to the waveguide port e Set the frequency to be continuous from fmin to fmax Requesting calculations A single plane of magnetic symmetry on the X 0 plane may be used for this model The solution requests are e Create a vertical far field request in the XZ plane 180 lt lt 180 with p 0 and 2 steps May 2014 FEKO Examples Guide DIELECTRIC RESONATOR ANTENNA ON FINITE GROUND A 12 5 Meshing information Use the Coarse auto mesh setting The curvature of the model will cause further refinement to the complex parts of the model to ensure that the geometry is accurately represented CEM validate After the model has been meshed run CEM validate Take note of any warnings and errors Correct any errors before running the FEKO solution kernel A 12 3 Results The calculated S for 3 GHz to 6 GHz is shown in Figure A 12 2 A radiation pattern at 3 6 GHz is shown in Figure A 12 3 Results are shown for both modelling methods Reflection coefficient dB 25 Waveguide port MoM SEP Modal port FEM MoM 30 1 1a _ m SSN 3 0 3 5 4 0 4 5 5 0 5 5 6 0 Frequency GHz Figure A 12 2 Inp
18. wb 2 wl width of wa depth of wb and height of wl in the Y direction e Set the region of the of the cuboid to air e Select the four faces that represent the waveguide boundary walls all faces except the one at the origin and the one opposite to it where the modal port will be located and set their face properties to Perfect electric conductor e Set the solution method of the region to FEM May 2014 FEKO Examples Guide DIFFERENT WAYS TO FEED A HORN ANTENNA A 11 6 e Create the horn using the flare primitive with its base centre at the origin using the defini tion method Base centre width depth height top width top depth The bottom width and bottom depth are wa and wb The height top width and top depth are hl ha and hb respectively e Delete the face at the origin as well as the face opposite to the face at the origin e Union the waveguide section and the flare section e Set a local mesh size of lambda 20 on the back face of the waveguide e Add a FEM modal port to the back face of the waveguide e Add a FEM modal excitation to the port with the default magnitude and phase e Set the frequency to freq e Set the total source power no mismatch to 5 W Requesting calculations A plane of magnetic symmetry at the X 0 may be used as well as a plane of electric symmetry at the Y 0 The solution requests are e Define a far field request in the YZ plane with 2 steps for the E plane cut e Define a fa
19. 0 1 0 May 2014 FEKO Examples Guide HORN FEEDING A LARGE REFLECTOR H 3 3 e Set the face properties of the reflector to use Large element PO always illuminated during the solution e Decouple the MoM and LE PO by enabling the Decouple PO and MoM solutions option on the High frequency tab under Solve Run Solver settings e Set a magnetic plane of symmetry at z 0 and an electric plane of symmetry at Y 0 e Set the frequency to freq Requesting calculations Create a full 3D far field request with an increment of 5 for 0 over the range 180 lt lt 180 and an increment of 5 for over the range 0 lt lt 180 On the Advanced tab select continuous far to be calculated Spatially continuous far field allow the far field to be re sampled to any resolution in POSTFEKO Meshing information Use the coarse auto mesh setting Reduce simulation time in this example by using the coarse mesh setting The standard mesh setting is recommended in general CEM validate After the model has been meshed run CEM validate Take note of any warnings and errors Correct any errors before running the FEKO solution kernel Save the file and run the solver Note that this is a large simulation and may take a relatively long time to complete The model that has been created will be referred to as the original model throughout the rest of this example H 3 2 MLFMM horn and PO reflector For the second example simulate
20. May 2014 FEKO Examples Guide ANTENNA COUPLING USING AN IDEAL RECEIVING ANTENNA B 2 3 constructed from multiple near field request surfaces It is important that the near field surface spans the entire radiating area of the antenna For the helix antenna the surface needs to be all around the antenna and thus using spherical near field surface would work well Create a near field request with the following settings e Use the spherical coordinate system e On the Advanced tab choose to export the fields to ASCII file e Request the following ranges Axis Start End Increment r 0 45 0 45 0 The files generated by this simulation will be used in the following model of this example B 2 2 Using receiving antenna techniges to model the helix antenna In the Antenna_Coupling_ Receiving _Antenna cfx model the Yagi Uda antenna and the large conducting sheet are added The receiving antenna is correctly positioned and rotated relative to these by specifying a local coordinate system Creating the model The steps for setting up the model are as follows e Define variables freq 1 654e9 Design frequency of the helix lambda c0 freq The wavelength in free space yagi_ld lambda 0 442 The length of director element yagi_li lambda 0 451 The length of active element yagi_lr lambda 0 477 The length of reflector element yagi_d 0 25 lambda Spacing between yagi elements
21. This is used as a reference to see the effect that the glass lens and the solution method has on the gain patterns Both the FEM and GO solutions show good agreement with one another and show the expected focussing of the electric fields in the main beam direction The memory and runtime requirements of running the GO model are orders of magnitudes lower than that of the full wave FEM solution May 2014 FEKO Examples Guide A LENS ANTENNA WITH GEOMETRICAL OPTICS GO RAY LAUNCHING A 13 4 Reference GO FEM Figure A 13 2 The computed radiation pattern compared to the reference solution and a full FEM result May 2014 FEKO Examples Guide WINDSCREEN ANTENNA ON AN AUTOMOBILE A 14 1 A 14 Windscreen antenna on an automobile Keywords windscreen input impedance antenna In this example we consider the input impedance of a windscreen antenna Windscreen antennas are antennas that are located in or on a windscreen The windscreen can consist of one or more layers and the different layers do not have to be meshed and thus simulation time is greatly reduced when compared to conventional methods Figure A 14 1 shows a 3D representation of the car and windscreen being simulated in this example Figure A 14 1 3D view of an automobile and a windscreen antenna A 14 1 Creating the rear windscreen model The model is created by importing geometry instead of using CADFEKO s geometry tools The required geometry
22. Y parameter Specify the one port admittance matrix manually Y 1 Zload e Connect the general network to the final port i e the port of the longest dipole element e Set the continuous interpolated frequency range from 35 MHz to 60M MHz e Add a voltage source to the port at the first dipole at the origin Note that it will be required to connect all of the ports transmission lines and the network together in the schematic view Figure A 7 2 The network schematic view showing the connected transmission lines general networks and ports Requesting calculations Electric symmetry may be applied to the plane at y 0 A far field pattern is requested in the vertical plane 180 lt 0 lt 180 with 0 and 2 incre ments May 2014 FEKO Examples Guide LOG PERIODIC ANTENNA A 7 3 Meshing information Use the standard auto mesh setting with wire segment radius equal to 0 01 Note that all wires have local radii set to radN CEM validate After the model has been meshed run CEM validate Take note of any warnings and errors Correct any errors before running the FEKO solution kernel Save the file and run the solver A 7 2 Results The vertical gain in dB at 46 29 MHz and the input impedance over the operating band of the LPDA are shown in Figure A 7 3 and Figure A 7 4 respectively Far field gain Figure A 7 3 The vertical gain of a LPDA antenna at 46 29 MHz May 2014 FEKO Example
23. infinite ground MoM a Pin feed finite ground FDTD Figure A 8 5 The E plane radiation pattern of the three microstrip patch models May 2014 FEKO Examples Guide PROXIMITY COUPLED PATCH ANTENNA WITH MICROSTRIP FEED A 9 1 A 9 Proximity coupled patch antenna with microstrip feed Keywords patch antenna aperture coupling microstrip feed proximity coupling voltage on an edge infinite substrate This example considers a proximity coupled circular patch antenna from 2 8 GHz to 3 2 GHz The meshed geometry is shown in Figure A 9 1 The feed line of the patch is between the patch and the ground plane Figure A 9 1 Proximity coupled circular patch antenna The lighter triangles are on a lower level closer to the ground plane A 9 1 Circular patch Creating the model The steps for setting up the model are as follows e Set the model unit to millimetres e Define the following variables epsr 2 62 The relative permittivity patch_rad 17 5 The patch radius line_len 79 The strip line length line_width 4 373 The strip line width offset 0 Feed line offset from the patch centre substrate_d 3 18 The substrate thickness f_min 2 8e9 The lowest simulation frequency f_max 3 2e9 The highest simulation frequency e Create a new dielectric medium called substrate with relative permittivity of epsr and dielectric loss tangent of 0 e Create a circular m
24. w_1 0 0 Enter the name of the efe and hfe in the Source group box The coordinate system is a spherical coordinate system with radius 1 3 w_1 and the number of 0 and points is equal to 36 and 71 respectively Requesting calculations Ensure that the 3D far field is still requested from the previously generated model Save the file and run the solver May 2014 FEKO Examples Guide HORN FEEDING A LARGE REFLECTOR H 3 6 H 3 6 Spherical excitation and LE PO reflector In this model the far field that was stored in the sph file from the horn model is used As for the previous model when the near fields were used the horn is removed from the full model and replaced by an equivalent source Creating the model The original model is opened again and saved with a different name The horn is removed and a new excitation is created for the dish The steps for setting up the model containing the reflector and equivalent spherical mode source are as follows e Open the original model and save it under a new name e Remove the waveguide excitation and port e Remove the horn from the model e Create a new spherical mode source at 0 0 0 Select the sph file that has been created during the previous simulation Requesting calculations No calculation requests need to be created since the far field request was created in the original model and it has not been removed Save the file and run the solver H 3 7 Comparat
25. 0 0 0 with a radius of plate_radius This is used to model the finite ground plane of the helix e The helix antenna is created using a Helix primitive with Definition method of Base centre radius pitch angle turns Origin at 0 0 0 Radius of helix_radius Pitch angle of helix_alpha Number of turns is n e The Helix and Ellipse are unioned to indicate connectivity e A wire port is added on the segment at the start of the Helix e A voltage excitation is applied to the port e Set the frequency to freq Meshing information Use the standard auto mesh setting with wire segment radius equal to wire_radius Requesting calculations A full 3D far field is requested The far field pattern receiving antenna requires a far field pattern file to be exported On the Advanced tab choose to export the field to an ASCII file The far field pattern will be stored in a file with the ffe extension The spherical modes required for the spherical mode receiving antenna can be calculated as part of the same far field request On the Advanced tab choose to calculate spherical mode coefficients and also to export the coefficients to an ASCII file The spherical mode expansion coefficients will be stored in a file with the sph extension The near field aperture receiving antenna requires near field points around the antenna to be calculated and stored The near field aperture can be any shape and the aperture can also be
26. 1 2 Bistatic RCS of a thin dielectric sheet May 2014 FEKO Examples Guide RCS AND NEAR FIELD OF A DIELECTRIC SPHERE C 2 1 C 2 RCS and near field of a dielectric sphere Keywords dielectric plane wave sphere bistatic RCS monostatic RCS A lossless dielectric sphere with radius of 1 m and relative permittivity equal to 36 is excited by means of an incident plane wave The wavelength of the incident field is 20 m in free space 3 33 m in the dielectric The near field inside and outside the sphere as well as the RCS of the sphere are calculated and compared to theoretical results The calculation is done using the surface equivalence principle J Figure C 2 1 A 3D view of the dielectric sphere and plane wave excitation The CADFEKO preview of the far field request and the symmetry planes are also shown on the image C 2 1 Dielectric sphere Creating the model The steps for setting up the model are as follows e Define the following variables lambda 20 Free space wavelength freq cO0 lambda Operating frequency radius 1 Sphere radius epsilon 36 Relative permittivity e Create a new dielectric called diel and set its relative permittivity equal to epsilon e Create a sphere with at the origin and set its radius to the value of radius e Set the region properties of the sphere to be of medium diel e Add a plane wave excitation with 0 180 and 0 e Set the frequency equal to var
27. 13 14 15 Frequency GHz Figure E 2 2 S parameters for the waveguide step discontinuity May 2014 FEKO Examples Guide USING A NON RADIATING NETWORK TO MATCH A DIPOLE ANTENNA E 3 1 E 3 Using a non radiating network to match a dipole antenna Keywords network S parameters Z parameters Y parameters Touchstone ideal matching dipole A short dipole approximately 3A is matched to be resonant at 1 4 GHz This is done using two methods one using an LC matching section and another using the matching network s S parameters as an input network The S parameters are provided in the Matching s2p Touch stone file The matching network is simply a 2 43 pF shunt capacitor and a 41 2 nH series inductor con nected between the excitation and the dipole Figure E 3 1 is an illustration of the short dipole with a network feed as well as the matching network schematic L 41 2nH C 2 43 pF Figure E 3 1 A model of a dipole The schematic represents the matching network used at the port E 3 1 Dipole matching using a SPICE network Creating the model The steps for setting up the model are as follow e Set the model unit to millimetres e Define the following variables fmin 1 3e9 The minimum operating frequency fmax 1 5e9 The maximum operating frequency h 70 The height of the dipole wireRadius 0 1 Radius of dipole wire segments e Create a 70 mm h line along the Z axis with its c
28. 1999 where the input admittance of a forked monopole is considered Figure H 1 1 The forked dipole geometry H 1 1 Forked dipole model Creating the model The model is simple and can be created as follows e Create the following variables fmin 100e6 The minimum calculation frequency fmax 300e6 The maximum calculation frequency wireRadius 1e 3 The radius of the wire segments e Create the following named points pointi 0 01 0 0 5 point2 0 0 0 01 point3 0 01 0 0 466 May 2014 FEKO Examples Guide A FORKED DIPOLE ANTENNA CONTINUOUS FREQUENCY RANGE H 1 2 point4 0 0 0 01 e Create 2 line primitives One from pointi to point2 and a second from point2 to points e Apply a Copy Copy and mirror operation on the two lines The mirror operation should be around the UV plane e Create a line primitive between the named points point2 and point4 Label this line as feed e Union all of the lines into a single part e Add a wire port to the middle of the feed wire e Apply a voltage excitation 1V 0 50 to the port e Set the solution frequency settings to Continuous interpolated range between fmin and fmax Requesting calculations For this example we only wish to view the input impedance of the forked dipole No calculations therefore need be specifically requested Meshing information Use the standard auto mesh setting with the wire segment radius equal
29. 2 4 GHz is simulated in two ways The problem is first divided so that the feed network is characterised save S parameters to a Touchstone file and then the Touchstone file is used as a non radiating network to feed the patch The two models feed network and patch antenna are then combined so that the full simulation model contains feed and patch is performed The input impedance as well as the simulation time and memory required for the two methods are compared We will see that subdividing the problem greatly reduces the required resources However when using this technique the field coupling between the feed network and the patch is not taken into account which results in a variation in the results The steps that are required to create the model are not part of the this example However several important points regarding the creation process will be highlighted Figure E 4 1 is an illustration of RHC patch antenna with the feed network A Figure E 4 1 The model of a RHC patch antenna with feed network E 4 1 Feed network The feed network consists of a branch line coupler that divides the power evenly with 90 degree phase difference between the outputs The output signals are then extended to the patch feed interfaces using microstrip transmission lines The entire system is designed in a 120 Q system reference impedance Creating the model The steps for setting up the model are as follows e Define a new dielectric nam
30. 3 1 Full_Model cfx The reference model used to compute the coupling between two horn antennas located as shown in Figure B 3 1 directly without using a precomputed far field pattern B 3 1 The horn antenna in free space In the Pyramidal_Horn cfx model shown in Figure B 3 2 the 3D radiation pattern of a horn at 1 645 GHz is computed and saved to an ffe file The horn is excited using a waveguide port The horn is placed with its excitation on the YZ plane To account for the phase centre offset the far field is calculated with the offset axis origin at X 21 6 cm Two planes of symmetry are used in the model in the Y 0 and Z 0 planes May 2014 FEKO Examples Guide USING A POINT SOURCE AND IDEAL RECEIVING ANTENNA B 3 2 The calculation of the phase centre that is required for accurate placement of the radiation pat tern of the horn is beyond the scope of this example but is discussed in Example 35 of the ScriptExamples pdf guide A phase centre calculation script is also available on the FEKO website that allows the phase centre to be calculated in POSTFEKO Technically the phase offset needs to be calculated for each frequency The far field pattern should also be calculated for each frequency Due to the narrow bandwidth of the calculation this step is omitted in this example B 3 2 Using the computed horn radiation pattern in a coupling calculation In Point_Source_Coupling cfx the two horn antennas are substituted with
31. F 1 1 finite array lt c0 csee coeca ees eeagaeses awe A 17 1 finite conductivity 0 cece eee eee D 1 1 finite ground plane ee eee eee A 4 1 G geometrical optics eee eee eee A 13 1 GO sinridieieumedininddiegeanigeteechnetes A 3 1 H half wavelength dipole 65 A 1 1 helix antenna eee eee eee eee B 2 1 OBE igs einige tin aie ea eit vipeareie aine ie A 3 1 horn antenna ee ee eee A 11 1 B 3 1 I ideal matching 00 cece eee ee eee E 3 1 ideal receiving antenna B 2 1 B 3 1 infinite ground 26 A 5 1 A 12 1 infinite planar Green s function A 5 1 A 9 1 A 12 1 input impedance A 1 1 A 12 1 E 1 1 L lens ANtENNG eae re E EA EE A 13 1 lossy Metal s nsdsrnecci sedeesedioeetiaaeeuses A 2 1 M magnetic field probe cc5sccdesegadecedanes D 3 1 Magnetic Resonance Imaging F 2 1 materials dielectric solid A 2 1 A 13 1 C 2 1 lossy metal 00c ee eee A 2 1 D 1 1 PEG sersan nso dorson e E EE a eaten A 2 1 method of moments A 1 1 A 2 1 D 1 1 D 4 1 F 2 1 MUCTOSMIP serenas aan aa aaa A 8 1 A 9 1 feed line per csderssderisisresigrisoicivsi A 9 1 microstrip coupler ee eee eee E 5 1 microstrip feed see eee eee ee eee A 8 1 microstrip filter 00 c eee eee eee eee E 1 1 MIMO asserts netes dne
32. Frequency MHz Figure D 2 2 Voltage induced in a terminated shielded cable by an external source May 2014 FEKO Examples Guide A MAGNETIC FIELD PROBE D 3 1 D 3 A magnetic field probe Keywords shielding EMC HOBE probe current plane wave magnetic field A magnetic field probe in the form of a frame antenna with shielding against electric fields is con structed and simulated The wavelength at the operating frequency 30 MHz is approximately 10 m Figure D 3 1 A 3D view of the H probe and the plane wave incidence excitation symmetry plane shown D 3 1 Magnetic field probe Creating the model The steps for setting up the model are as follows e Define the following variables freq 30e6 The operating frequency lambda c0 freq The free space wavelength rBig 1 Radius of revolution rSmall 0 1 The pipe radius wireRad 5e 3 The radius of the inner wire segments of the probe e Create an elliptic arc with radius rSmall Set the workplane of the elliptic arc at an origin of rBig 0 0 and set the U and V vectors respectively to 0 0 1 and 1 0 0 e Rotate the arc over an angle of 185 around the Z axis e Spin the ellipse over an angle of 350 around the Z axis e Draw an elliptic arc through the centre of the toroidal section radius rBig start angle 0 end angle 360 e Add a plane wave excitation that loops over multiple incidence angles Let 0 lt
33. IN FRONT OF A CUBE A 2 1 A 2 Dipole in front of a cube Keywords dipole PEC metal lossy dielectric A half wavelength dipole is placed three quarters of a wavelength away from a cube The radi ation pattern is calculated and the effect of the nearby cube on the radiation pattern is demon strated Three different cubes are modelled in this example The first cube is PEC perfect electrically conducting the second is a metal cube that has a finite conductivity and the third cube is made as a solid dielectric material The second and third models are an extension of the first model The examples should be set up sequentially i Figure A 2 1 A 3D view of the dipole with a metallic cube model symmetry planes shown A 2 1 Dipole and PEC cube Creating the model The steps for setting up the model are as follows e Define the following variables lambda 4 Free space wavelength freq c0 lambda Operating frequency h lambda 2 Length of the dipole radius 2e 3 Wire radius of dipole e Create a cube The cuboid is created with the Base corner width depth height definition method The base corner is at 0 lLambda 4 lambda 4 and with the width depth and height set equal to lambda 2 By default the cube will be PEC e Create a line between the points 0 0 h 2 and 0 0 h 2 Place the wire 3 4 lambda away from the cube by translating it by 8 4 lambda in the negative X direction e Add
34. Rotate the local workplane around the U axis by 90 so that the plate is defined in the XZ plane The origin of the workplane is at strip_length strip_feed_arc_radius w 2 strip_feed_arc_radius 0 The feed has a width of w and a depth of substrate_height e Create geometry that will be used for the bend of the microstrip by creating two ellipses The outer boundary of the arc is defined by a circular surface with a centre point at strip_length strip_feed_arc_radius substrate_height and radial di mensions of strip_feed_arc_radiustw 2 The inner boundary of the arc is defined by a circular surface with a centre point at strip_length strip_feed_arc_radius substrate_height and radial di mensions of strip_feed_arc_radius w 2 Subtract the inner circle from the outer circle A full 360 loop should now be visible in the view e Union all of the geometry e Delete the curved face that does not form part of the microstrip bend Once deleted the microstrip should consist of a straight section a bend and a feed e Simplify the remaining microstrip geometry to remove any unwanted edges The resulting geometry represents half of the top microstrip e Copy and rotate the microstrip by 180 around the U axis This represents half of the bottom microstrip e Create a ground plate using a rectangle with a base corner at 0 substrate_depth 2 0 a width of substrate_width 2 and a depth of substrate_depth e Create the g
35. a correctly ori ented and positioned ideal receiving antenna and a radiation pattern point source The coupling can be computed based on the power that is received in W by the receiving antenna and comparing it to the power that was transmitted By setting the transmitting antenna power to 1 W on the power settings tab only the received power needs to be recorded The coupling is then related to the received power by Received power Coupling gg 10 log10 Transmitted power B 3 3 The reference model In Full_Model cfx both horns and the plate are included Symmetry is used in the Y 0 and Z 0 planes The coupling between the antennas is computed directly by requesting S parameters CEM validate After the model has been meshed run CEM validate Take note of any warnings and errors Correct any errors before running the FEKO solution kernel B 3 4 Results The received power at the ideal receiving antenna is extracted from POSTFEKO Figure B 3 3 shows the fully calculated model compared to the point source approximation It can be seen that the results match reasonably well where the differences can be attributed to the point source approximation Figure B 3 2 The 3D model of the horn that is used to generate the ffe file May 2014 FEKO Examples Guide USING A POINT SOURCE AND IDEAL RECEIVING ANTENNA B 3 3 Coupling between antennas Full model Point source approx Coupling dB
36. advantage of using the MLFMM but larger examples will show a proportionally larger resource savings Figure H 2 1 shows an illustration of the trihedral with a plane wave excitation d Figure H 2 1 Plane wave incident on an electrically large trihedral H 2 1 Large trihedral Creating the model The steps for setting up the model are as follows e Define the following variables lambda 1 Free space wavelength freq cO0 lambda The operating frequency s 3 lambda Side lengths of the trihedral e Create the first polygonal plate The three corner points are 0 0 0 s 0 0 and 0 s 0 e Create the second polygonal plate The three corner points are 0 0 0 0 0 s and s 0 0 e Create the third polygonal plate The three corner points are 0 0 0 0 s 0 and 0 0 s e Union the plates e Define a linear plane wave excitation at 0 60 and 45 e Set the frequency to freq The model is now set up to be solved with the default MoM The model should be set to use the MLFMM with default values All solution method settings including MLFMM are set on the Solver settings dialog May 2014 FEKO Examples Guide USING THE MLFMM FOR ELECTRICALLY LARGE MODELS H 2 2 Requesting calculations The solution requests are e Create a 180 vertical far field request 180 lt lt 180 with p 45 and 2 steps Meshing information Use the standard auto mesh setting CEM validate
37. by going to the face properties of the plate in the detail tree of CADFEKO On the solution tab use the dropdown box named Solve with special solution method and choosing Uniform theory of diffraction UTD Now when meshing is done in CADFEKO the plate will not be meshed into triangular elements Remove the symmetry definitions for the UTD example the number of elements is so small that it is faster to simulate without symmetry Meshing information Use the standard auto mesh setting with the wire radius set to rho After changing the solution method on the plate to UTD the model must be remeshed UTD plates are not meshed and a single element will be created for the entire plate May 2014 FEKO Examples Guide DIPOLE IN FRONT OF A PLATE A 3 4 CEM validate After the model has been meshed run CEM validate Take note of any warnings and errors Correct any errors before running the FEKO solution kernel A 3 5 Dipole and a GO plate Creating the model The model is identical to the MoM model note that we are changing the MoM model and not the UTD model The only change that is required is that the solution method to be used on the plate must be changed This change is made by going to the face properties of the plate in the detail tree of CADFEKO On the solution tab use the dropdown box named Solve with special solution method and choosing Geometrical optics GO ray launching Meshing information Use the standard auto
38. cannot be taken into account when substituting the feed with a general non radiating network the results are slightly different as can be seen in figure E 4 2 The great advantage really becomes clear when the user has to design the antenna and cannot or does not want to change the feed network This allows fast simulations during antenna de velopment Verification can then be done after development that includes a full 3D field solution including the patch and the feed network May 2014 FEKO Examples Guide SUBDIVIDING A MODEL USING NON RADIATING NETWORKS E 4 5 Table E 4 1 Comparison of resources for the simulations per frequency Impedance Ohm Model RAM Time Total Time Full model 12 95 Mb 519 519 Network only 1 83 Mb 50 Patch with general network 3 56 Mb 133 183 Excitation Radiating Re Z Radiating Im Z Non radiating Re Z Non radiating Im Z 2 1 2 2 2 3 2 4 2 5 Frequency GHz 2 6 2 7 2 8 2 9 Figure E 4 2 Input impedance real and imaginary of the path with radiating and non radiating feed May 2014 FEKO Examples Guide A MICROSTRIP COUPLER E 5 1 E 5 A Microstrip coupler Keywords microstrip coupler FDTD edge excitation S parameters coupling The coupling of a four port microstrip coupler is presented over a frequency band between 2 5 5 0 GHz This example is based on the paper On the design of planar microw
39. cece een ence ences A 3 1 MOM PO fiestccccdtiwsiedeadiiwsisiedaas A 3 1 MoM UTD lt ce seedsenahensitestanie ASI E EEE E E E E H 4 1 periodic boundary conditions A 16 1 C 3 1 C 4 1 planar multilayer substrate Green s function A 8 1 surface equivalence principle A 2 1 A 8 1 C 2 1 E 1 1 1 2 SYMMECUrY cece cand adie a cae ae eee rke A 9 1 thin dielectric sheet approximation C 1 1 UID iiaiai a Sci Sa bias en ceed Wa Giles ee condenses B 2 1 sphere creation see eee ee eee eee C 2 1 surface equivalence principle A 2 1 C 2 1 T thin dielectric sheet approximation C 1 1 time domain eee e cece eee eee G 1 1 Touchstone cece e eee ees E 3 1 E 4 1 transmission line eee cece eeee A 7 1 trihedral reflector 2c eee eee ee ee H 2 1 U UTD shoicanncteeigeenniee oret babes A 3 1 B 2 1 WwW waveguide 605 A 11 1 E 2 1 H 4 1 waveguide modes c cece eee eee E 2 1 WINKSCLEEN soc cates daSeaide dead Gouda dees A 14 1 WIPES fic 6 crdste cus E Gua noha Gua noha Gua nana E A 1 1 Y Y parameters 0s5 ccseccasteatssbucseuedses oe E 3 1 Yagi Uda antenna A 5 1 A 6 1 B 2 1 Z A PaLaMeters aia cmanamaanameamandaynaneaynacecs E 3 1 I 3 www feko info e FEKO is a product of EM Software amp Systems S A Pty Ltd
40. closed region will be a perfect electric conductor The region type of the Lens part is changed to be dielectric Glass Requesting calculations To model the dielectric lens with the geometrical optics approximation we need to specify the solution method for the Lens S1 and Lens S2 faces From the Solution tab of the Face properties dialogue select the Geometrical optics GO ray launching solution method In general to check which solution methods are being applied the user can use the View by solution parameters tool The geometrical optics approximation has two user options that affect the solution e Maximum no of ray interactions default three May 2014 FEKO Examples Guide A LENS ANTENNA WITH GEOMETRICAL OPTICS GO RAY LAUNCHING A 13 3 e Ray launching settings default Automatic The present implementation does not take into account the local curvature at the interaction point This assumption approximation could fail when using a large number of ray interactions and where the local curvature of the geometry can t be neglected These settings can also be changed on the Solver settings High frequency dialog Unselect the automatic setting for the angular increment Set the dielectric GO ray launching settings for theta and phi to 1 5 respectively The analysis is requested at a single frequency of 30 GHz The dielectric lens is illuminated by a radiation pattern point source The radiation pattern is X pola
41. continuous frequency range from f_min to f_max Requesting calculations Request a full 3D far field Magnetic symmetry may be applied to the plane at x 0 Meshing information Use the standard auto mesh setting Note that local mesh refinement was used on several of the edges see description above To reduce the number of mesh elements the growth rate was set to 40 between slow and fast This setting increases the rate at which the size of the mesh elements increase from smaller to larger triangles CEM validate After the model has been meshed run CEM validate Take note of any warnings and errors Correct any errors before running the FEKO solution kernel May 2014 FEKO Examples Guide MODELLING AN APERTURE COUPLED PATCH ANTENNA A 10 4 A 10 2 Aperture triangles in infinite ground plane This model uses the planar multilayer substrate to replace the dielectric substrate of the first model Aperture triangles are used to model the aperture in the PEC ground plane between the layers This approach provides an equivalent model that requires fewer resources than the full SEP model Creating the model The steps for setting up the model are as follows e Define the same variables as for the full SEP model e Follow the same creation steps as for the first model to create some of the components The following components are required for this model The aperture The patch The feed The feedPort It is also require
42. e Define the same variables as for the FEM MoM model e Define named points excite_b 0 6 5 1 e Create dielectrics May 2014 FEKO Examples Guide DIELECTRIC RESONATOR ANTENNA ON FINITE GROUND A 12 4 Create a dielectric named dome with relative dielectric permittivity of epsr and di electric loss tangent of zero Create a dielectric named isolator with relative dielectric permittivity of 2 33 and dielectric loss tangent of zero e Create a new workplane an place its origin at excite_b Set this workplane as the default workplane e Create a cylinder Set respectively the Radius and Height equal to rBig and hBig Modify the label to FeedBase e Create another cylinder Set respectively the Radius and Height equal to r and h hBig Modify the label to FeedPin e Union the two cylinders e Set the default workplane back to the global XY plane e Create a disk on the XY plane with the radius set equal to rDisk e Create a sphere with a radius of rDome Set the label to InnerDome e Union everything and name the unioned part DRA e Delete the bottom half of the sphere e Set the region properties of the cylinder FeedBase to the dielectric of type isolator e Set the region of the half sphere to be the dielectric named dome e Set the region of the cylinder FeedBase to be the dielectric named isolator e Set all of the faces in the model to PEC except the top and bottom faces of the FeedBase and
43. efieldcomp3 EfieldLimit SCALE THE MAGNETIC FIELD VALUES Scale the values to indicate percentages The percentage represents the field value relative to the limit of the standard nfPt hfieldcomp1 nfPt hfieldcomp1 HfieldLimit nfPt hfieldcomp2 nfPt hfieldcomp2 HfieldLimit nfPt hfieldcomp3 nfPt hfieldcomp3 HfieldLimit end pf DataSet ForAl1Values calculateRADHAZThresholds nf Note that in essence the values being returned are no longer near fields As such interpret them carefully in POSTFEKO return nf May 2014 FEKO Examples Guide ANTENNA RADIATION HAZARD RADHAZ SAFETY ZONES D 4 6 NRPB89 nf This example illustrates how advanced calculations can be performed to display radiation hazard zones The NRPB 89 standards are used pf NearField GetDataSet yagi StandardConfiguration1 nf3D function calculateRADHAZThresholds index nf Get a handle on the indexed near field point local nfPt nf index Set up the threshold according to the standards local freq nfPt AxisValue frequency 1e9 Frequency in GHz local EfieldLimit 97 1 math sqrt freq local HfieldLimit 0 258 math sqrt freq SCALE THE ELECTRIC FIELD VALUES Scale the values to indicate percentages The percentage represents the field value relative to the limit of the standard nfPt efieldcomp1 nfPt efieldcomp1 EfieldLimit nfPt efieldcomp2 nfPt efieldcomp2 EfieldLimit
44. excitation The second port is connected to the wire port in the centre of the wire Requesting calculations No solution requests are required in CADFEKO May 2014 FEKO Examples Guide USING A NON RADIATING NETWORK TO MATCH A DIPOLE ANTENNA E 3 3 Meshing information Use the standard auto mesh setting with wire segment radius wireRadius CEM validate After the model has been meshed run CEM validate Take note of any warnings and errors Correct any errors before running the FEKO solution kernel Save the file and run the solver E 3 3 Results The reflection coefficient of the matched and unmatched dipole is shown in Figure E 3 2 It may be difficult to see any variation of the reflection coefficient of the unmatched dipole since it is very close to 0 dB over the whole band Reflection coefficient m 10 9 T Q O 20 8 oO 5 3 30 Not matched a0 SPICE e S2P network 50 1 30 1 32 1 34 1 36 1 38 1 40 1 42 1 44 1 46 1 48 1 50 Frequency GHz Figure E 3 2 The reflection coefficient of the dipole before and after application of the feed matching May 2014 FEKO Examples Guide SUBDIVIDING A MODEL USING NON RADIATING NETWORKS E 4 1 E 4 Subdividing a model using non radiating networks Keywords network S parameters Touchstone input impedance far field patch feed net work non radiating network A right hand circularly polarised patch antenna at
45. files for the import are available as part of your FEKO installation and is located in the ExampleGuide_mode1s directory Creating the model The steps for setting up the model are as follows e Import the Parasolid geometry for the car car_geometry x_b Set the scale equal to 1 e Rename the three parts to be more descriptive of the geometry There should be a part for the car_body one for the antenna and one for the windscreen e Union the car and the antenna This ensures that these structures will be connected during meshing Note that the windscreen is not part of the union e Add a wire port to the wire that connects the antenna to the car s chassis See Figure A 14 1 for an indication of where this port is located Ensure that a vertex wire port is created instead of the default segment wire port May 2014 FEKO Examples Guide WINDSCREEN ANTENNA ON AN AUTOMOBILE A 14 2 e Add a voltage source to the port that has been created e Define the following dielectric materials glass 7 tand 0 03 pvb_foil 3 tan d 0 05 e Create a layered dielectric called windscreen_layers with the following properties Layer 1 2 1 mm thick glass Layer 2 0 76 mm thick pvb_foil Layer 3 2 1 mm thick glass e Create a new windscreen definition similar to how a dielectric is created that uses the windscreen_layers layer definition Set the Offset L 2 1e 3 0 76e 3 This places a reference plane i e the geometry t
46. layer named thin_dielsheet Select substrate as the dielectric material for the layer and set the thickness equal to variable d May 2014 FEKO Examples Guide RCS OF A THIN DIELECTRIC SHEET C 1 2 e Create a rectangular plate in the XY plane centred around the origin The width X axis is the value of a and depth is b e Set the face medium property of the plate to thin_dielsheet e Add a single incident plane wave excitation from the direction 92 thetai and phii Set the polarisation angle to etai e Set the frequency to freq Requesting calculations The geometry of the problem is symmetric around the X 0 and Y 0 planes but the excitation has no symmetry Two planes of geometric symmetry are therefore specified in the model settings The solution requests are e Create a vertical far field request 180 lt lt 180 with 0 Meshing information e Use the standard auto mesh setting CEM validate After the model has been meshed run CEM validate Take note of any warnings and errors Correct any errors before running the FEKO solution kernel C 1 2 Results The bistatic RCS of the dielectric sheet at 100 MHz as a function of the angle 0 in the plane p 0 is shown in Figure C 1 2 May 2014 FEKO Examples Guide RCS OF A THIN DIELECTRIC SHEET C 1 3 Radar cross section 25 RCS dBm 2 A O 55h SN 180 150 120 90 60 30 0 30 60 90 120 150 180 Theta deg Figure C
47. lt 90 with 6 90 and 2 increments Meshing information Use the standard auto mesh setting with the wire segment radius equal to 0 25 May 2014 FEKO Examples Guide MICROSTRIP PATCH ANTENNA A 8 3 CEM validate After the model has been meshed run CEM validate A 8 2 Pin fed FDTD model Creating the model The model is now solved by means of the FDTD solver It is still pin fed as in the previous example Figure A 8 2 A 3D representation of a pin fed microstrip patch antenna on a finite ground The model is extended with the following steps performed sequentially e Activate the finite difference time domain FDTD solver e Change the continuous frequency range to linearly spaced discrete points ranging from fmin to fmax with the number of frequencies set to 51 e Define the boundary condition settings Set the Top Z Y Y X and X boundaries to Open and Automatically add a free space buffer Set the Bottom Z boundary to Perfect electric conductor PEC and Do not add a free space buffer Meshing information Use the standard auto mesh setting with the wire segment radius equal to 0 25 CEM validate After the model has been meshed run CEM validate A 8 3 Pin fed planar multilayer substrate Creating the model This model is an extensions of the first model The substrate is now modelled with a planar multilayer substrate Green s functions It is still pin fed as in the previous two example
48. model of which is provided with the FEKO installation The important details for this example are e The coil has an inner radius of 15 cm and an RF shield radius of 17 54 cm e The elliptical phantom has a major radius of 11 cm and a minor radius of 8 5 cm Average head tissue properties are assigned to the phantom 36 and 0 657 e Capacitive loads C 4 15 pF are added to the wire ports between the end ring gaps on both sides of the birdcage NOTE this specific example is solved with MoM SEP but MoM FEM or FDTD could also be suitable choices Requested calculations A standard configuration is used to calculate the fields and currents at 300 MHz e The frequency specified per configuration for the standard configuration is set to 300 MHz e 2 voltage sources are added to the I and Q feed ports for the quadrature excitation The magnitude is set to 20 V for both and a 90 phase delay is set on the Q port May 2014 FEKO Examples Guide MAGNETIC RESONANCE IMAGING MRD BIRDCAGE HEAD COIL EXAMPLE F 2 2 e Currents and the near fields at z 0 are requested A second S parameter configuration is used to calculated the S parameters for the coil e The frequency is set to continuous interpolated covering 290 310 MHz e Both the I and Q port are set to active for the calculation Meshing information In order to resolve the geometry of the coil accurately a custom mesh size is used The triangle length is set
49. muscle sphere r 0 03 Radius of the outer sphere rM 0 025 Radius of the inner sphere lambda c0 freq Free space wavelength wireRadius 1e 3 Radius of the dipole wire e Create the media May 2014 FEKO Examples Guide EXPOSURE OF MUSCLE TISSUE USING MOM FEM HYBRID F 1 2 Create a dielectric named Muscle_Parallel_Fibers_Ovine it is available in the media library Create a dielectric named air with a relative permittivity of 1 and dielectric loss tangent of zero e Create a sphere at the origin with a radius set to the defined variable rM Set the label to Muscle e Create a sphere at the origin with a radius set to the defined variable rA Set the label to Air e Union Muscle and Air e Use Muscle_Parallel_Fibers_Ovine for the region properties of the inside sphere e Set the region properties of the region between the inside and outside sphere to the dielec tric called air e Set both regions to be solved using the finite element method FEM e Create the line a distance of d away from the centre of the sphere Set the Start point as 0 Lambda 4 d and the End point as 0 lambda 4 d e Add wire vertex port on the middle of the wire e Add the voltage source on the port 1 V 0 50 Q e Set the total source power no mismatch to 1 W e Set a continuous frequency range from f_min to f_max Requesting calculations In the X 0 plane use magnetic symmetry In the Y 0 plane
50. of patch substrate base_width 0 5 lambda Width of the patch substrate 0 5 lambda Length of the patch substrate base_height 0 02 1lambda Height of the patch substrate patch_width 0 3 lambda Width of the patch antenna patch_length 0 3 lambda Length of the patch antenna base_length pin_pos patch_length 4 Distance of feed pin from patch centre e Create a dielectric medium named substrate with relative permittivity of er and zero dielectric loss tangent e Create the substrate using the cuboid primitive with the base centre width depth height definition method The side lengths are base_width and base_length and has a thick ness of base_height May 2014 FEKO Examples Guide PERIODIC BOUNDARY CONDITIONS FOR ARRAY ANALYSIS A 16 2 e Create the patch by creating a rectangle with the base centre width depth height defini tion method The base centre should be located at 0 0 base_height Set the width and depth respectively to the defined variable patch_length and patch_width e Create the feed pin as a wire between the patch and the bottom of the substrate Set the Start point to pin_pos 0 0 and the End point to pin_pos 0 base_height e Union all the elements and label the union antenna e Set the region of the cuboid to substrate e Set the faces representing the patch and the ground below the substrate to PEC e Add a segment wire port on the middle of the wire e Add a voltage sour
51. option on the High frequency tab under Solve Run Solver settings e Set the face properties of the reflector to use Large element PO always illuminated during the solution Note that a notice will be encountered when running the solution as result of using symmetry in conjunction with the MLFMM Using symmetry will not lead to reduction of memory or run time as only the geometry is mirrored for a model solved by the MLFMM Requesting calculations Ensure that the 3D far field is still requested from the previously generated model Save the file and run the solver H 3 4 Generate equivalent aperture and spherical mode sources using only the horn The model is now simplified by simulating the horn by itself A set of near field points are calculated around the horn and then used as a source for the reflector May 2014 FEKO Examples Guide HORN FEEDING A LARGE REFLECTOR H 3 5 Creating the model The model is created by saving the previous model with a new name and making the required changes First we delete the dish from the original model and create a model containing only the horn The near and far field information is calculated and saved to a file The steps for setting up the model containing only the horn are as follows e Open the original model and save it under a new name e Remove the reflector from the model Requesting calculations Request a 3D far field with an origin at 0 0 0 180 lt lt 180
52. remain ing are then the top of the microstrip line and the top of the shielding box e Create a planar multilayer substrate Add a layer of type substrate that has a thickness of substrate_height The top of the substrate is at z substrate_height Add a PEC ground plane to the bottom of the substrate layer e As there is an infinite ground plane in this model the microstrip port may be used to define the excitation Microstrip ports are attached to each of the port edges These ports are then referenced in the S parameter solution request The polarisation of the ports should be chosen such that the positive terminals indicated by a red cylinder in the 3D view are on the microstrip e Set a local mesh size on the microstrip lines faces of strip_width 0 7 Requesting calculations The solution requests are e Create an S parameter request with Port1 active and 50 2 reference impedances Port2 should be added but not be active Meshing information Use the standard auto mesh setting May 2014 FEKO Examples Guide A MICROSTRIP FILTER E 1 6 CEM validate After the model has been meshed run CEM validate Take note of any warnings and errors Correct any errors before running the FEKO solution kernel E 1 4 Results The S parameters for all 3 cases are computed over the frequency range 1 5 GHz to 4 GHz The results for the S parameters are shown in Figure E 1 4 and E 1 5 From the scattering parameters at the input and ou
53. run CEM validate Take note of any warnings and errors Correct any errors before running the FEKO solution kernel A 16 3 Pin fed patch Squint pattern by phase shift definition Creating the model Use the same geometry as for the first model Meshing instructions are also the same Change the periodic boundary condition settings as follow e Manually specify the phase shift in both directions to be uJ 61 56 and u2 0 Requesting calculations Use the same far field calculations as for the first model CEM validate After the model has been meshed run CEM validate Take note of any warnings and errors Correct any errors before running the FEKO solution kernel A 16 4 Pin fed patch Squint pattern by squint angle definition Creating the model Use the same geometry as for the first model Meshing instructions are also the same Change the periodic boundary condition settings as follow e Determine the phase shift by setting the beam angle for Theta 20 and Phi 0 May 2014 FEKO Examples Guide PERIODIC BOUNDARY CONDITIONS FOR ARRAY ANALYSIS A 16 4 Requesting calculations Use the same far field calculations as for the first model CEM validate After the model has been meshed run CEM validate Take note of any warnings and errors Correct any errors before running the FEKO solution kernel A 16 5 Results Figure A 16 2 shows the far field gain for the broadside models of a single patch element with the eff
54. static domain is stored in a file which can be reused in subsequent simulations By storing the solution to the static domain which in this case is the waveguide FEKO only needs to calculate the effect of the feed pin location in further simulations The resource requirements for each iteration are given in Table H 4 1 Note that the first run took significantly longer than the rest This effect will become more pronounced as the size of the static domain increases relative to the dynamic domain Iteration Memory MBytes Runtime seconds 1 231 780 87 4 2 231 863 15 7 3 231 863 10 6 4 231 863 9 8 5 231 863 9 4 6 231 863 9 3 8 231 863 9 6 9 231 863 9 7 10 231 863 9 3 11 231 863 9 3 12 231 863 9 1 13 231 863 9 5 14 231 863 10 0 15 231 863 9 0 Table H 4 1 Comparison of resource requirements for each iteration The port is optimally matched when the magnitude of the reflection coefficient is as small as possible or the input impedance is equal to 50 Q On the Smith chart depicted in Figure H 4 2 we can see this condition is met roughly at iteration 6 This corresponds to a feed pin position given by Eq H 4 1 6 pin_offset 6x pin step_size 39 H 4 1 May 2014 FEKO Examples Guide OPTIMISE WAVEGUIDE PIN FEED LOCATION H 4 4 S parameter 0 7 1 1 4 Figure H 4 2 Smith chart showing the reflection coefficient for each feed pin position May
55. the feed pin using a line start point 0 pin_offset 0 end point 0 pin_offset pin_length workplane origin 0 waveguide_length 2 0 e Add a segment port at the connection point between the feed and the waveguide floor e Place a waveguide port at the other end of the waveguide This will absorb the power injected by the pin feed e Apply a voltage excitation 1V 0 50 Q to the wire port e Set the frequency to freq Requesting calculations Magnetic symmetry exists in the X 0 plane but no performance gain is experienced when used in conjunction with the NGE No solution requests are required since the input impedance and reflection coefficient is always available as output for all voltage sources in the model Setting up optimisation e An optimisation search is added with the Grid search method and 15 default points e The following parameters are set n min 1 max 15 grid points 15 e Set an Impedance goal to minimise the magnitude of the reflection coefficient May 2014 FEKO Examples Guide OPTIMISE WAVEGUIDE PIN FEED LOCATION H 4 3 Meshing information Use the fine auto mesh setting and set the wire segment radius to radius CEM validate After the model has been meshed run CEM validate Take note of any warnings and errors Correct any errors before running OPTFEKO H 4 2 Results The first time the solver is run the full calculation needs to be performed The solution to the
56. the horn using the MLFMM and the dish reflector using physical optics PO Creating the model The steps for setting up the model are as follows e Open the original model and save it under a new name e Solve the model with the multilevel fast multipole method MLFMM e Couple the MLFMM and PO by enabling the Couple PO and MoM MLFMM solutions iter ative technique option on the High frequency tab under Solve Run Solver settings May 2014 FEKO Examples Guide HORN FEEDING A LARGE REFLECTOR H 3 4 e Set the face properties of the reflector to use PO always illuminated during the solution Note that a notice will be encountered when running the solution as result of using symmetry in conjunction with the MLFMM Using symmetry will not lead to reduction of memory or run time as only the geometry is mirrored for a model solved by the MLFMM Requesting calculations Ensure that the 3D far field is still requested from the previously generated model Save the file and run the solver H 3 3 MLFMM horn and LE PO reflector For the third example simulate the horn using the MLFMM and the dish reflector using large element physical optics LE PO The steps for setting up the model are as follows e Open the original model and save it under a new name e Solve the model with the multilevel fast multipole method MLFMM e Couple the MLFMM and LE PO by enabling the Couple PO and MoM MLFMM solutions iterative technique
57. the model e Set the region inside the waveguide step to free space e Rename the faces that form the waveguide to Port1 and Port2 where Port1 sits on the outer face of the Ku band waveguide section and Port2 sits on the outer face of the X band waveguide section e Apply waveguide ports to both faces Port1 and Port2 Ensure that the reference vector indicated by a white line for both ports are in the XY plane e Confirm that the propagation direction of the waveguide excitation is into the waveguide in both cases e Set the frequency to be continuous from fmin to fmax Requesting calculations Magnetic symmetry in the X 0 plane and electric symmetry in the Z 0 are used The solution requests are e An S parameter calculation is requested Fundamental mode for both ports Only Port1 needs to be active Meshing information Use the fine auto mesh setting CEM validate After the model has been meshed run CEM validate Take note of any warnings and errors Correct any errors before running the FEKO solution kernel E 2 2 Waveguide step model FEM The model is almost the same as for the MoM model so it will be used as a base for the FEM model May 2014 FEKO Examples Guide S PARAMETER COUPLING IN A STEPPED WAVEGUIDE SECTION E 2 3 Creating the model Make a copy of the MoM model and make the following changes e Remove the two waveguide ports e Apply FEM modal ports to both faces Port1 and Port2 e Crea
58. the requested far field gain in dB May 2014 FEKO Examples Guide DIPOLE IN FRONT OF A PLATE A 3 1 A 3 Dipole in front of a plate modelled using MoM FDTD UTD GO and PO Keywords MoM HOBE UTD PO GO FDTD dipole radiation pattern far field electrically large plate A dipole in front of an electrically large square plate is considered This simple example illustrates how to solve a model using different techniques First the dipole and the plate is solved with the traditional MoM The plate is then modified so that it can be solved with higher order basis function MoM FDTD UTD GO and later PO and LE PO The MoM UTD MoM GO MoM PO and MoM LE PO hybrid solutions demonstrated here are faster and require fewer resources than the traditional MoM solution When applicable these approximations can be used to greatly reduce the required solution time and resources required when they are applicable Figure A 3 1 A 3D view of the dipole in front of a metallic plate A 3 1 Dipole in front of a large plate Creating the model The steps for setting up the model are as follows e Define the following variables d 2 25 Separation distance between dipole and plate 3 lambda 4 h 1 5 Length of the dipole lambda 2 a 4 5 Half side length of plate rho 0 006 e The wire dipole is a distance d from the plate in the U axis direction The dipole is h long and should be centred around the U axis Create th
59. the same medium In this case we needed to embed the ports fully inside the substrate dielectric Figure E 1 3 A zoomed in 3D view of one of the edge feed excitations Requesting calculations The solution requests are e Create an S parameter request with Porti active and 50 2 reference impedances Port2 should be added but not be active Meshing information Use the standard auto mesh setting May 2014 FEKO Examples Guide A MICROSTRIP FILTER E 1 5 CEM validate After the model has been meshed run the CEM validate E 1 3 Microstrip filter on an infinite substrate Planar multilayer Green s function Creating the model Only the shielding box and the microstrip lines are required The lower face of the shielding box and the substrate are removed and modelled using a planar multilayer substrate The changes that must be made to the FEM model are given below e Delete the S parameter request and both of the line ports including the line segment ge ometry used to define the port locations e Set the region properties of the two regions back to MoM MLFMM with surface equivalence principle SEP default Also set the air the substrate regions back to Free space e Delete the bottom face of the shielding box as well as the bottom part of the microstrip line The box should now be open from below and all faces should be PEC e Delete the face surrounding the microstrip line and stub The only horizontal faces
60. to 4 cm and a local mesh size of 3 cm is set for the elliptical phantom region CEM validate After the model has been meshed run CEM validate Take note of any warnings and errors Correct any errors before running the FEKO solution kernel F2 2 Results The S parameters for the head coil are shown in Figure F 2 2 as a function of frequency _ S parameter S1 1 _ S parameter S1 2 S parameter S1 2 S parameter S2 2 S parameters dB 290 292 294 296 298 300 302 304 306 308 310 Frequency MHz Figure F 2 2 S parameters for the I and Q feed ports of the coil Figure F 2 3 shows the current and near field results at 300 MHz The B1 and ratio B1 B1 plots are obtained using the MRI quantities POSTFEKO automation script which can be found in the same folder as the other files for this example Other scripts and updates can be downloaded from www feko info support lua scripts May 2014 FEKO Examples Guide MAGNETIC RESONANCE IMAGING MRD BIRDCAGE HEAD COIL EXAMPLE F 2 3 Figure F 2 3 Surface currents on the coil rungs with the phantom hidden left B1 field distribution at z 0 center and the ratio of B1 B1 right are shown May 2014 FEKO Examples Guide Chapter G Time domain examples TIME ANALYSIS OF THE EFFECT OF AN INCIDENT PLANE WAVE ON AN OBSTACLE G 1 1 G 1 Time analysis of the effect of an incident plane wave on an obstacle Keywords time
61. use electric symmetry No symmetry can be used in the Z 0 plane The solution requests are Create a near field request at 0 0 0 a single request point Meshing information Use the standard auto mesh setting Set the wire segment radius to wireRadius CEM validate After the model has been meshed run CEM validate Take note of any warnings and errors Correct any errors before running the FEKO solution kernel F 1 2 Results The electric field strength as a function of frequency is illustrated in Figure F 1 2 May 2014 FEKO Examples Guide EXPOSURE OF MUSCLE TISSUE USING MOM FEM HYBRID F 1 3 Near field 30 27 _ 24 A 2 24 D Q u 48 15 12 0 1 0 2 0 3 0 4 0 5 0 6 0 7 0 8 0 9 1 0 Frequency GHz Figure F 1 2 Electric field at the centre of the sphere over frequency May 2014 FEKO Examples Guide MAGNETIC RESONANCE IMAGING MRD BIRDCAGE HEAD COIL EXAMPLE F 2 1 F 2 Magnetic Resonance Imaging MRI birdcage head coil ex ample Keywords MRI birdcage S parameters Lua scripting B1 This example demonstrates the simulation of an MRI birdcage head coil with an elliptical phan tom shown in Figure F 2 1 The coil is a 7T highpass design with the tuning capacitors placed in the end ring gaps between the 16 rungs Figure F 2 1 Geometry for the 7T head coil with elliptical phantom F 2 1 Birdcage Creating the model This example consists of complicated geometry the
62. yagi_rho lambda 0 0025 The radius of yagi elements e Define named points helix centre 1 5 2 3 4 1 5 as the helix antenna location yagi_centre 1 5 2 3 4 1 5 as the Yagi Uda antenna location e The Yagi Uda antenna is created using line primitives Create a line with start point 0 0 yagi_1i 2 and end point as 0 0 yagi_1i 2 Set the label to yagi_active May 2014 FEKO Examples Guide ANTENNA COUPLING USING AN IDEAL RECEIVING ANTENNA B 2 4 e Create a line with start point 0 yagi_d yagi_ld 2 and end point 0 yagi_d yagi_ld 2 Set the label to yagi_director e Create a line with the start point 0 yagi_d yagi_lr 2 and the end point 0 yagi_d yagi_lr 2 Set the label to yagi_reflector e Create a copy of yagi_director Translate form 0 0 0 to 0 yagi_d 0 e Create a copy of yagi_director Translate form 0 0 0 to 0 2 yagi_d 0 e Union the wires and modify the label to yagi_antenna e A wire port is added on the vertex at the centre of the active element of the yagi antenna e A voltage excitation is applied to the port e Set the simulation frequency to freq e Rotate yagi_antenna with 90 15 Note that an expression may be added to the field not just a value e Translate yagi_antenna from 0 0 0 to yagi_centre yagi_centre yagi_centre e The rectangle primitive is used to create the plate Set the local workplane to the global Y Z plane Ctrl Shift and cl
63. 0 2 mm for the X band waveguide respectively Only the Hio mode is considered The critical frequency for the chosen H mode in the smaller Ku band waveguide is 0 f 3 9 4871 GHz We want to compute S parameters from this cut off frequency up to 15 GHz using adaptive frequency sampling A Figure E 2 1 3D view of a waveguide step from Ku to X band E 2 1 Waveguide step model MoM Creating the model The steps for setting up the model are as follows e Set the model unit to millimetres e Define the following variables fmin 9 4872e9 The minimum calculation frequency fmax 15e9 The maximum calculation frequency al 15 8 Width of the Ku section a2 22 9 Width of the X section b1 7 9 Height of the Ku section b2 10 2 Height of the X section 11 12 Length of the Ku section 12 12 Length of the X section May 2014 FEKO Examples Guide S PARAMETER COUPLING IN A STEPPED WAVEGUIDE SECTION E 2 2 Note that the minimum calculation frequency fmin is just above the Ku band cutoff fre quency f as explained previously e Create the Ku band waveguide section with its base corner at a1 2 11 b1 2 with a width of a1 a depth of 11 and a height of b1 e Create the X band waveguide section on the positive Y axis Set its base corner at a2 2 0 b2 2 with a width of a2 a depth of 12 and a height of b2 e Union the two cubes and then simplify
64. 1 60 1 61 1 62 1 63 1 64 1 65 1 66 1 67 1 68 1 69 1 70 Frequency GHz Figure B 3 3 The comparative results for the full model simulation and the simulation using pre calculated radiation pattern representations of the horn antennas in the model May 2014 FEKO Examples Guide Chapter C Radar cross section RCS RCS OF A THIN DIELECTRIC SHEET C 1 1 C 1 RCS of a thin dielectric sheet Keywords RCS thin dielectric sheet TDS plane wave The electrically thin dielectric plate modelled with the thin dielectric sheet approximation is illuminated by an incident plane wave such that the bistatic radar cross section may be calculated at 100 MHz A Figure C 1 1 A 3D representation of a thin dielectric sheet with a plane wave excitation excitation and symmetry planes shown C 1 1 Dielectric sheet Creating the model The steps for setting up the model are as follows e Define the following variables freq 100e6 Operating frequency d 0 004 Plate thickness a 2 Width of plate b 1 Depth of plate epsr 7 Relative permittivity tand 0 03 Loss tangent thetai 20 Zenith angle of incidence phii 50 Azimuth angle of incidence etai 60 Polarisation angle of incident wave e Create a dielectric called substrate with relative permittivity equal to epsr and dielectric loss tangent set to the value of tand e Create a layered dielectric with a single
65. 2 3 compare the near field along the Z axis and the radar cross section as a function of the angle to exact mathematical results RCS calculations are displayed on a far field graph The Y axis of the RCS graph has been changed to a logarithmic scale for improved visualisation May 2014 FEKO Examples Guide RCS AND NEAR FIELD OF A DIELECTRIC SPHERE C 2 3 E Field 0 5 E a 10 D 2 i W 15 Exact e FEKO 20 2 0 1 5 1 0 0 5 0 0 0 5 1 0 1 5 2 0 Z position m Figure C 2 2 Near field along the Z axis RCS 0 10 20 x D 30 g 40 50 Exact e FEKO 60 0 30 60 90 120 150 180 Theta deg Figure C 2 3 Bistatic radar cross section of the dielectric sphere May 2014 FEKO Examples Guide SCATTERING WIDTH OF AN INFINITE CYLINDER C 3 1 C 3 Scattering width of an infinite cylinder Keywords periodic boundary condition plane wave MoM Using a 1 dimensional periodic boundary condition the scattering of an infinite cylinder is ef ficiently computed as defined below The results are compared with a literature reference C A Balanis Advanced Engineering Electromagnetics Wiley 1989 pp 607 sw ki 2 lz I gt um TT 7 A poo PTR P Figure C 3 1 A 3D view of the unit cell of the infinite cylinder with the 1 D periodic boundary condition shown C 3 1 Infinite cylinder Creating the model The model consis
66. 2014 FEKO Examples Guide Chapter I User interface tools POSTFEKO APPLICATION AUTOMATION I 1 1 I 1 POSTFEKO Application automation Keywords application automation API POSTFEKO online help scripting forms reporting Application automation is a tool that can increase productivity when dealing with predictable and repeatable POSTFEKO sessions This example will illustrate how an automation script can be used to configure a session and export a report that highlights the antenna properties of the model It will be illustrated that a script can be used on various models with repeatable results Fig ure I 1 1 shows equivalent pages for two different antenna types p HornAntennaQuickReport pdf Adobe Reader Fle E3 p patchantennaQuickReport pdf Adobe Reader of xj x File Edit view Window Help File Edt view Window Help 4268 2B 62 ze 2 k7 Tools Sign Comment R amp B 2 75 22 ie Tools Sign Comment B 3 Isometric View Isometric View Total Gain dBi Total Gain dBi 2 10 0 5 0 Figure 1 3D View Patch Antenna Automated Quick Report Figure I 1 1 Results of the automatic report generation Note that the base language for the automation interface is Lua For a complete guide on the Lua language we refer you to the official Lua Reference Manual www lua org manual 5 1 and Programming introductio
67. 99 6 96 0 10 20 30 40 50 60 70 80 90 Plane Wave Theta deg Figure D 3 2 The current in an arbitrary segment is plotted as a function of the plane wave excitation incidence angle Note that each segment will result in a slightly different current as a function of the plane wave excitation May 2014 FEKO Examples Guide ANTENNA RADIATION HAZARD RADHAZ SAFETY ZONES D 4 1 D 4 Antenna radiation hazard RADHAZ safety zones Keywords yagi radiation hazard scripting Safety standards differ from country to country industry to industry and may change over time This example illustrates how POSTFEKO scripts can be used to fully customise the calculation of such results A yagi antenna is simulated with a full 3D near field cube of the immediate surroundings Using math scripts in POSTFEKO the radiation standards are used to identify the safety zones for the antenna z Figure D 4 1 The 3D safety zones for 80 and maximum i e 100 exposure levels according to the INIRC 88 standard D 4 1 CADFEKO The antenna in a given environment gives rise to electric and magnetic fields These fields will differ in strength and shape depending on the input power antenna design and surrounding environment Creating the model The steps for setting up the model are as follows e Define the following variables physical dimensions based on initial rough design freq 1e9 The operating frequency
68. D 2 1 Monopole and ground Creating the model The steps for setting up the model are as follows e Define the following variables fmin 1e6 The minimum operating frequency fmax 35e6 The maximum operating frequency wireRadius 1e 3 The wire radius of the monopole e Create a monopole 10 m high with beginning and end point coordinates of 0 0 0 and 0 0 10 e Add a wire segment port to the base of the monopole e Add a voltage source to the port 1 V 0 50 Q May 2014 FEKO Examples Guide CALCULATING FIELD COUPLING INTO A SHIELDED CABLE D 2 2 e Set the total source power no mismatch equal to 10 W e Define a PEC ground plane e Set the frequency to be continuous from fmin to fmax e Create a cable path definition The cable path for this example consists of the following list of x y z coordinates 0 2 0 01 10 2 0 01 10 5 0 01 7 8 0 01 0 8 0 01 e Create a cable harness A harness can contain multiple cables and make up the different sections of a cable path e Create two cable connectors One at the start and one at the end of the cable path Label them startConnector and endConnector respectively Both connectors will have two pins one that is live and one for ground i e the cable shield e Create the RG58 cable cross section The RG58 cable is one of the predefined coaxial cable cross sections that can be selected from the list The cross section is used t
69. ING A MODEL USING NON RADIATING NETWORKS E 4 4 E 4 3 Patch with radiating feed network The advantage of being able to model the feed as a non radiating general network can only be seen when comparing the results and the required resources with the full 3D simulation Creating the model The patch antenna model touchstoneFedPatch cfx will be used as base model and the branch coupler model feedNetwork cfx imported The complete simulation is then per formed The steps for setting up the model are as follows e Open the file touchstoneFedPatch cfx and save it as completePatch cfx e Delete the voltage excitation remove the general network connections and then delete the general network and all the ports e Import the file feedNetwork cfx Import only the geometry and mesh rules Merge identical variables and media e Delete Port2 and Port3 Keep Port1 and Port4 i e the outer ports e Union the two structures e Add a voltage source to Port1 1 V 0 50 2 e Add a 120 Q load to Port4 Requesting calculations Ensure that all faces of the feed network are set to have a local mesh size of wl The model can the be meshed using the standard auto mesh setting Save the file and run the solver E 4 4 Results The difference in solution time and required main memory is tabled in Table E 4 1 We see that the solution time is reduced by subdividing the problem Since the field coupling between the feed and the patch
70. Length e Create a line segment between 0 pinOffset h and 0 pin0ffset 0 e Union the parts together e Create a dielectric medium with a permittivity of epsr and label it substrate e Create a planar multilayer substrate with a height of h The medium should be substrate Ensure that a ground plane is defined at the bottom of the dielectric layer e Add a port to the wire segment e Add a voltage source to the port with the default values e Set the frequency to freq E amp a lt N E E E ra Figure A 17 2 The array layout that will be analysed The geometry above represents the base element which is not included in the array calculations by default Create the array depicted in figure A 17 2 by performing the following steps e Create a planar array Request four elements in both dimensions Space the elements lamO apart e Convert the planar array into a custom array This makes it possible to delete reposition or rotate individual elements of the array e Delete all elements corresponding to the third row and column There should now be nine elements left Note that each element can also have a different orientation Elements are rotated by modifying the local workplane of the custom antenna array elements No elements need to be rotated for this example but the user in encouraged to rotate some of the elements after the simulation has completed to investigate the effect on the array pattern
71. METAL in Watt Losses due to impedances at vertices connection points basis fu no power loss 1193 3 2296E 03 W Total loss in the vertices 3 2296E 03 W Loss metal total 3 2296E 03 W W Both the power lost in the conjugate load from the full model and the power received by the ideal receiving antennas can be plotted in POSTFEKO Receiving antenna far field pattern with name FarfieldReceivingAntennal RECEIVED POWER FOR IDEAL RECEIVING ANTENNA FAR FIELD PATTERN Received power ideal match assumed 3 0477E 03 W Relative phase of received signal 4 6809E 00 deg Receiving antenna spherical modes with name RXAntennal RECEIVED POWER FOR IDEAL RECEIVING ANTENNA FAR FIELD PATTERN Received power ideal match assumed 3 0735E 03 W Relative phase of received signal 3 4302E 00 deg Receiving antenna near field aperture with name NearfieldReceivingAntenna1 RECEIVED POWER FOR RECEIVING ANTENNA NEAR FIELD APERTURE Received power 2 9418E 03 W The phase is relative to the global FEKO phase reference The ideal receiving antenna solutions requires considerably less resources than the full model If the receiving antenna is moved further away from the transmitting antenna and geometry then the difference in the results will be smaller May 2014 FEKO Examples Guide USING A POINT SOURCE AND IDEAL RECEIVING ANTENNA B 3 1 B 3 Antenna coupling using a point source and ideal receiving antenna Keywords coupling S p
72. MoM PO 2 23 6 Large element PO MoM LE PO 0 29 1 47 Uniform theory of diffraction MoM UTD 0 08 1 32 Geometric optics MoM GO 1 28 4 23 FDTD 101 23 1310 Table A 3 1 Comparison of resource requirements for the model using different solver techniques May 2014 FEKO Examples Guide A MONOPOLE ANTENNA ON A FINITE GROUND PLANE A 4 1 A 4 A monopole antenna on a finite ground plane Keywords monopole finite ground radiation pattern far field current A quarter wave monopole antenna on a finite circular ground plane is constructed and simulated The circular ground has a circumference of three wavelengths and the wire has a radius of 1 mm The operating frequency is 75 MHz z A Figure A 4 1 A 3D view of the monopole on a finite circular ground symmetry planes shown A 4 1 Monopole on a finite ground Creating the model The steps for setting up the model are as follows e Define the following variables freq 75e6 Operating frequency lambda c0 freq Free space wavelength R 3 lambda 2 pi Radius of the ground plane wireRadius 1e 3 Radius of the monopole wire segments e Create the ground using the ellipse primitive Set the radii equal to the defined variable R and the label to ground e Create a line between 0 0 0 and 0 0 lambda 4 and rename as monopole e Union the wire and the ground e Add a wire vertex port on the line The port preview should show
73. Union the three parts e Set the frequency to freq e Set the total source power no mismatch to 5 W Requesting calculations One plane of magnetic symmetry in the X 0 plane may be used The solution requests are e Define a far field request in the YZ plane with 2 steps for the E plane cut e Define a far field request in the XZ plane with 2 steps for the H plane cut Meshing information Use the coarse auto mesh setting with a wire radius of 0 1 cm We use coarse meshing for this example to keep the simulation times as low as possible CEM validate After the model has been meshed run CEM validate Take note of any warnings and errors Correct any errors before running the FEKO solution kernel May 2014 FEKO Examples Guide DIFFERENT WAYS TO FEED A HORN ANTENNA A 11 4 A 11 2 Waveguide feed Creating the model The wire feed model is changed to now use the waveguide feed The line is deleted and the wire port removed The following additional steps are followed e Set a local mesh size of lambda 20 on the back face of the waveguide e A waveguide port is applied to the back face of the guide CADFEKO automatically de termines the shape of the port rectangular and the correct orientation and propagation direction It is good practice to visually confirm that these have indeed been correctly chosen as intended by observing the port preview in the 3D view e A waveguide mode excitation is applied to the wave
74. Union the two cuboids and set their region properties to the substrate dielectric e Union the substrate layers and the rest of the geometry Solution settings and requests The following solution setting changes and requests are required e Create an S parameter request where all ports are included with a 50 Q reference impedance Only Port1 is active This will replace the standard configuration that was created by de fault e Set a linearly spaced frequency range from f _min to f_max with 101 frequency samples e Enable the finite difference time domain FDTD solver e Modify the boundary conditions so that only the z directed boundary conditions are set to automatically add a free space buffer The other four boundary conditions should not add a free space buffer Meshing information Use the standard auto mesh setting CEM validate After the model has been meshed run CEM validate Take note of any warnings and errors Correct any errors before running the FEKO solution kernel E 5 2 Results Figure E 5 2 shows the simulated coupling parameters are compared to the published data The simulated results are in good agreement with the measured results Any differences are most likely due to uncertainties regarding the model dimensions or dielectric properties May 2014 FEKO Examples Guide A MICROSTRIP COUPLER E 5 4 S parameters 0 5 10 m D 2 15 2 E S21 FDTD g0 S FDTD
75. a es A 14 1 A 15 Design of a MIMO elliptical ring antenna characteristic modes A 15 1 A 16 Periodic boundary conditions for array analysis 04 A 16 1 A 17 Finite array with non linear element spacing 24 A 17 1 B Antenna placement B 1 Antenna coupling on an electrically large object B 1 1 B 2 Antenna coupling using an ideal receiving antenna B 2 1 B 3 Using a point source and ideal receiving antenna B 3 1 C Radar cross section RCS C 1 RCS ofa thin dielectric Gh66t 6 v6 ww ws da ee eS ew ee SE eR ee C 1 1 C 2 RCS and near field of a dielectric sphere 0200 000 eee C 2 1 C 3 Scattering width of an infinite cylinder 02 000005 C 3 1 C 4 Periodic boundary conditions for FSS characterisation C 4 1 D EMC analysis cable coupling D 1 Shielding factor of a sphere with finite conductivity D 1 1 May 2014 FEKO Examples Guide CONTENTS ii D 2 Calculating field coupling into a shielded cable D 2 1 D 3 Amagpneti cfield probe sw oN SRE SK INR ORE TAO HO ROS D 3 1 D 4 Antenna radiation hazard RADHAZ safety zones 204 D 4 1 E Waveguide microwave circuits EL Sipe iler oe bo RRS Ra eae RA RRS See EAS OS E 1 1 E 2 S parameter coupling in a stepped waveguide section E 2 1 E 3 Using a non radiating network to match a dipole antenna
76. a wire port at the centre of the line e Add a voltage source to the port e Set the frequency to the defined variable freq May 2014 FEKO Examples Guide DIPOLE IN FRONT OF A CUBE A 2 2 Requesting calculations All electric fields will be tangential to the Y 0 plane and normal to the Z 0 planes An electric plane of symmetry is therefore used for the Z 0 plane and a magnetic plane of symmetry for the Y 0 plane The solution requests are e A horizontal radiation pattern cut is calculated to show the distortion of the dipole s pattern due to the proximity of the cuboid 0 lt lt 360 with 0 90 with 0 where and denotes the angles theta and phi Meshing information e Use the standard auto mesh setting e Wire segment radius radius CEM validate After the model has been meshed run CEM validate Take note of any warnings and errors Correct any errors before running the FEKO solution kernel A 2 2 Dipole and lossy metal cube The calculation requests and mesh settings are the same as in the previous model Extending the first model The model is extended with the following steps performed sequentially e Create a metallic medium called lossy_metal Set the conductivity of the metal to 1e2 e Set the region inside the cuboid to free space e Set lossy metal properties on the cuboid faces by right clicking in the details tree Set the Face medium to lossy_metal and the thickness to 0 005 Meshin
77. and electric field limits Standard Magnetic Electric Field Limits Magnetic INIRC88 Magnetic NRPB89 Electric INIRC88 Electric NRPB89 Magnetic Electric Field Limits mA m V m Frequency GHz Figure D 4 2 The definition of the standards used in the calculated band The 3D representation for the safety zones can be depicted in a variety of formats In the de scription image Figure D 4 1 the safety zones are indicated at 0 95 GHz Similar zones can be drawn for any value in the calculated frequency band as shown in Figure D 4 2 Figure D 4 3 shows how the field values at a specific position can be monitored to test for compliance to the radiation standards It can be seen that the electric field exceeds the maximum limit between 1 024 1 173 GHz The scripts The scripts that are used for the calculations are provided Note that they adhere to the standards only for the frequency band over which the model was simulated The resulting values for the May 2014 FEKO Examples Guide ANTENNA RADIATION HAZARD RADHAZ SAFETY ZONES D 4 4 NRPB 89 Standard 180 N a oO Electric Field V m 60 30 1 0 1 2 1 4 1 6 Frequency GHz Electric Field Limit E Field at 0 0316 0 067 0 2 m Figure D 4 3 The electric field values at a given location over frequency INIRC88 and NRPB89 near fields are technically no longer near fi
78. ar field MLFMM MLFMM PO MLFMM LE PO MoM LE PO Aperture LE PO Spherical LE PO 40 20 90 60 30 Theta deg Figure H 3 2 Gain of the reflector antenna calculated using different techniques over a 180 degree angle May 2014 FEKO Examples Guide HORN FEEDING A LARGE REFLECTOR H 3 8 Gain dBi Far field MLFMM MLFMM PO MLFMM LE PO MoM LE PO Aperture LE PO Spherical LE PO 84 85 86 87 88 Theta deg Figure H 3 3 Gain of the reflector antenna calculated using different techniques main lobe May 2014 FEKO Examples Guide OPTIMISE WAVEGUIDE PIN FEED LOCATION H 4 1 H 4 Optimise waveguide pin feed location Keywords waveguide NGE optimisation grid search In practice a waveguide can be fed using a pin placed a quarter of a waveguide wavelength from a terminated end of the waveguide This can be a difficult position to determine for ar bitrary waveguide cross sections since the waveguide wavelength is not always known This example will demonstrate how to use an optimisation grid search and the NGF solution settings to efficiently analyse the effect of the pin offset on the reflection coefficient Figure H 4 1 3D view of a waveguide fed with a pin feed H 4 1 Pin fed waveguide Creating the model The steps for setting up the model are as follows e Set the model unit to millimetres e Define the
79. arameters radiation pattern point source ideal receiving antenna This example demonstrates the computation of coupling between two horn antennas using a radiation pattern point source approximation and an ideal far field pattern receiving antenna The far field radiation point source can also be replaced by a spherical mode source The receiving antenna can be modelled as a spherical mode source or a near field aperture source instead of the far field pattern receiving antenna The best options for the source and the receiving antenna depends on the problem at hand It is left to the reader to experiment with the different source and receiving antenna modelling techniques The model geometry consists of two horn antennas pointing towards one another separated by a distance of 60 wavelengths Exactly half way between the antennas is a metallic plate that is effectively blocking the line of sight coupling between the antennas z Figure B 3 1 The full 3D model representation of the problem considered in this example This example consists of 3 models Pyramidal_Horn cfx A model of a horn antenna in free space used to precompute the far field radiation pattern to be used in the point source radiation pattern and ideal receiving an tenna parts of the ensuing models Point_Source_Coupling cfx A model that uses the far field radiation pattern of the horn antenna to efficiently extract the coupling between two horns as shown in Figure B
80. ariables freq 400e6 Operating frequency lambda c0 freq The wavelength in free space at the operating frequency lr 0 477 lambda Length of the reflector li 0 451 lambda Length of the active element ld 0 442 lambda Length of the directors d 0 25 lambda Spacing between elements h 3 Height of the antenna above ground epsr 10 Relative permittivity of the ground May 2014 FEKO Examples Guide YAGI UDA ANTENNA ABOVE A REAL GROUND A 5 2 sigma 1e 3 Ground conductivity wireRadius 1e 3 Wire radius 1 mm e Create the active element with start point as 0 1i 2 h and the end point as 0 11 2 h Set the label as activeElement e Add a vertex port in the centre of the wire e Add a voltage source on the port 1 V 0 50 2 e Create the wire for the reflector Set the Start point as d 1r 2 h and the End point as d 1r 2 h Set the label as reflector e Create the three wires for the directors Director Start point End point director1 d 1d 2 h d 1d 2 h director2 2 d 1d 2 h 2 d 1d 2 h director3 3 d 1d 2 h 3 d 1d 2 h e Create a dielectric called ground with relative permittivity of epsr and conductivity equal to Sigma e Set the lower half space to ground This can be done by setting the infinite plane to use the exact Sommerfeld integrals e Set the frequency to freq Reque
81. art of the input impedance of the windscreen antenna May 2014 FEKO Examples Guide DESIGN OF A MIMO ELLIPTICAL RING ANTENNA CHARACTERISTIC MODES A 15 1 A 15 Design of a MIMO elliptical ring antenna characteristic modes Keywords characteristic modes eigen value MIMO multiple input multiple output A characteristic mode analysis is performed on a ring structure This analysis is independent of any excitations and provide insight into how a structure resonates at the calculated frequencies Using this knowledge one can strategically excite a structure so that only the desired modes are utilised Figure A 15 1 shows the first four electric far field modes for the ring structure Figure A 15 1 The first four electric far field modes for the MIMO ring A 15 1 MIMO ring Creating the model The steps for setting up the model are as follows e Define the following variables rInU 21 Inner radius of the ring in the U direction rOutU 31 Outer radius of the ring in the U direction rInV rInU 0 8 Inner radius of the ring in the V direction rOutV rOutU 0 8 Outer radius of the ring in the V direction freq 2 4e9 Operating frequency e Set the model to millimetres e Create an elliptic arc centred at the origin with a radius of rOutU and rOutV in the u and v dimensions respectively Set the start and end angles from 0 90 e Create another elliptic arc centred at the origi
82. ation on FEKO LITE please see the Getting started manual and the Installation Guide What to expect The examples have been chosen to demonstrate how FEKO can be used in a selection of applica tions with a selection of the available methods Though information regarding the creation and setup of the example models for simulation is discussed these example descriptions are not intended to be complete step by step guides that will allow exact recreation of the models for simulation This document rather presents a guide that will help the user to discover and understand the concepts involved in various applications and methods that are available in FEKO while working with the provided models In each example a short description of the problem is given then the model creation is discussed after which the relevant results are presented May 2014 FEKO Examples Guide INTRODUCTION 2 More examples This set of examples demonstrates the major features of FEKO For more step by step examples please consult the Getting started guide Also consult the FEKO website for more examples and models specific documentation and other FEKO usage FAQ s and tips Contact information The contact details for each FEKO distributor is available at www feko info contact htm Please contact the distributor in your region about any FEKO queries or licences For more technical questions please contact the FEKO support team www feko info contact suppo
83. ave components using multilayer structures by W Schwab and W Menzel IEEE Trans MTT vol 40 no 1 Jan 1992 pp 67 72 Fig 9 Figure E 5 1 shows a top view of the model Note that there are multiple layers visible due to transparency b Poti Port2 Figure E 5 1 A top view of the microstrip coupler E 5 1 Microstrip coupler Creating the model The steps for setting up the model are as follows e Set the model unit to millimetres e Define the following variables di d2 epsr 2 2 Relative permittivity of substrate dielectric 2 22 Spacing 1 between apertures 12 51 Spacing 2 between apertures f_max 5e9 Highest simulation frequency f_min 2 5e9 Lowest simulation frequency s 10 Aperture side length strip_feed_arc_radius 2 s Radius of curved microstrip line strip_length 2 s d2 d1 Length of straight section for microstrip line substrate_depth 50 Depth of substrate substrate_height 1 58 Height of substrate substrate_width 140 Width of substrate May 2014 FEKO Examples Guide A MICROSTRIP COUPLER E 5 2 w 4 6 Width of the microstrip lines e Create a dielectric with a relative permittivity of epsr and label it substrate e Create a straight section of microstrip using a rectangle with a base corner at 0 w 2 substrate_height a width of strip_length and a depth of w e Create a rectangle that will be used for the feed
84. be dasa eee ce ennie A 15 1 MLEMM sai itive adalatanain rau ae deine ace hns B 1 1 H 2 1 MOM x webs sees ation ste hails Lae neers A 3 1 monopole antenna eeee eee A 4 1 MRI erisera ane Salen erras pene by wees eee gs F 2 1 N near Held ingerere geese qu rE TE D 1 1 non radiating network A 7 1 E 3 1 E 4 1 O Online help wacrcsdwaevdoaavseonevgensvs amie I 1 1 optimisation cee eee eee A 6 1 H 4 1 P PAtGh sacrwswhewendewenddvenidveandeenerense E 4 1 patch antenna 006 A 8 1 A 9 1 PEG scecduceidsetedcenedieee deuce ddeeadsemens A 2 1 pin feed cided ccasa cde sd peers renias A 8 1 A 11 1 planar multilayer substrate Green s function A 8 1 plane wave 006 C 1 1 C 2 1 D 1 1 PO iia eac ee edie T E N us at A 3 1 polygon plate eee eee eee eee ee C 1 1 proximity coupling e cece e eee A 9 1 pulse Shape cscscccsisnirissicisdirissisirsei G 1 1 R radiation pattern A 1 1 A 4 1 A 11 1 A 13 1 radiation pattern point source B 3 1 tay CACHE onc cce dese scseiarecd eielererere wnnarere winarene ene A 13 1 RCS radar cross section 000 C 2 1 Peal ground oc ccivsncevacerweetiwantiwan tenes A 5 1 POPOL ss ces sinrartiept cn mcaedwnie Sid tiie wd Geum ar de areas 1 1 1 resource requirements 000 H 2 1 results continuous frequency 24 H 1 1 CUITENE 2 6 cece cece cece eee e
85. before running the FEKO solution kernel A 9 2 Results Figure A 9 2 shows the reflection coefficient on the Smith chart May 2014 FEKO Examples Guide PROXIMITY COUPLED PATCH ANTENNA WITH MICROSTRIP FEED A 9 3 Reflection coefficient 0 7 1 1 4 Figure A 9 2 Reflection coefficient of the proximity coupled patch May 2014 FEKO Examples Guide MODELLING AN APERTURE COUPLED PATCH ANTENNA A 10 1 A 10 Modelling an aperture coupled patch antenna Keywords aperture triangles infinite planes SEP A patch antenna can be fed using a microstrip feed line coupling energy through an aperture in the ground plane underneath the patch This example will demonstrate how to model such a configuration using both a full model where the substrates are meshed as well an equivalent model using an infinite plane approximation The latter makes use of aperture triangles that allow energy to couple through an infinite PEC ground plane Figure A 10 1 shows a depiction of the geometry that will be used h Figure A 10 1 Top view of an aperture coupled patch antenna Opacity has been set so that all layers can be seen in the image A 10 1 Full SEP model Creating the model The steps for setting up the model are as follows e Define the following variables f_min 2 1e9 Minimum frequency in operating range f_max 2 3e9 Maximum frequency in operating range epsr_a 10 2 Relative permittivity for the botto
86. ce on the port 1 V 0 50 Q e Set the frequency to freq e Set the periodic boundary condition of the model to the end exactly on the edge of the substrate to expand in both the x and y dimensions e Manually specify the phase shift in both directions to be uJ 0 and u2 0 Requesting calculations The solution requests are e Create a vertical E plane far field request 180 lt lt 180 with 0 1 and 0 incre ments e Create another vertical E plane far field request 180 lt lt 180 with 0 1 and 0 increments This time request the calculation of a 10 x 10 array of elements on the Advanced tab Meshing information Use the standard auto mesh setting with wire segment radius equal to 0 0001 CEM validate After the model has been meshed run CEM validate Take note of any warnings and errors Correct any errors before running the FEKO solution kernel May 2014 FEKO Examples Guide PERIODIC BOUNDARY CONDITIONS FOR ARRAY ANALYSIS A 16 3 A 16 2 Pin fed patch Broadside pattern by squint angle definition Creating the model Use the same geometry as for the first model Meshing instructions are also the same Change the periodic boundary condition settings as follow e Determine the phase shift by setting the beam angle for Theta and Phi to 0 Requesting calculations Use the same far field calculations as for the first model CEM validate After the model has been meshed
87. cients and coupling between the antennas when mounted on the electrically large helicopter May 2014 FEKO Examples Guide ANTENNA COUPLING USING AN IDEAL RECEIVING ANTENNA B 2 1 B 2 Antenna coupling using an ideal receiving antenna Keywords coupling ideal receiving antenna far field data file ffe file helix antenna Yagi Uda antenna electrically large This example involves the calculation of the coupling between a helix antenna and a Yagi Uda antenna located in front of an electrically large metal plate as shown in Figure B 2 1 This is an electrically large problem and two approaches are used to accelerate the solution sig nificantly The plate is efficiently modelled as an UTD plate and the helix antenna is modelled as an ideal receiving antenna The receiving antenna can be modelled using a far field radiation pattern far field spherical modes or a near field aperture The ideal receiving antenna formula tion can be used only when the required far field spherical mode or near field aperture data is available or can be calculated in a separate simulation for an antenna In addition the antenna must be located an acceptable distance from all other physical structures that may influence the currents on the antenna This example will illustrate the use of all three receiving antenna techniques in a single model The simulation time received power and coupling between the antennas modelled using the three receiv
88. cite specific modes Ensure that loads and sources are specified per configuration before continuing 1 Request a characteristic mode configuration Only the first five modes should be calculated May 2014 FEKO Examples Guide DESIGN OF A MIMO ELLIPTICAL RING ANTENNA CHARACTERISTIC MODES A 15 3 e Request all currents e Request a full 3D far field with default sampling 2 Request a standard configuration The purpose of this configuration is to excite the first characteristic mode e Add a voltage source to the Eastern port 1 V 0 50 Q e Add a voltage source to the Western port 1 V 180 50 Q e Request all currents e Request a full 3D far field with default sampling 3 Request a standard configuration The purpose of this configuration is to excite the fifth characteristic mode e Add a source to the Eastern port 1 V 0 50 Q e Add a source to the Western port 1 V 0 50 Q e Add a source to the Northern port 1 V 180 50 Q e Add a source to the Southern port 1 V 180 50 Q Request all currents Request a full 3D far field with default sampling Meshing information Use the Fine auto mesh setting On the Advanced tab of the mesh dialog set the refinement factor to Fine This is to ensure that the geometry is accurately represented CEM validate After the model has been meshed run CEM validate Take note of any warnings and errors Correct any errors before running the FEKO solution kernel
89. d to split this plate into a top and bottom half e Create a planar multilayer substrate Add two layers Layer 1 should have a bottom ground plane a height of d_b and the medium should be set to top_layer Layer 2 should not have any ground plane a height of d_a and the medium should be set to bottom_layer The z value at the top of Layer 1 should be d_a e Union all of the geometry parts e Add and edge port between the two split components of feedPort Let the positive face correspond to the face attached to the ground plane Add a voltage source to the port with the default source properties e Set the solution method of the face representing the aperture to Planar Green s function aperture e In order to obtain accurate results whilst minimising resource requirements local mesh refinement is necessary on several of the geometry parts Set the local mesh refinement for the patch edges to lambda_b 40 Set local mesh refinement on the aperture face to ap_w 0 7 Set local mesh refinement on the feed face to feed_w 2 e Set the continuous frequency range from f_min to f_max May 2014 FEKO Examples Guide MODELLING AN APERTURE COUPLED PATCH ANTENNA A 10 5 Requesting calculations Request a full 3D far field Magnetic symmetry may be applied to the plane at x 0 Meshing information Use the standard auto mesh setting Note that local mesh refinement was used on several of the edges see descriptio
90. date Take note of any warnings and errors Correct any errors before running the FEKO solution kernel Save the file and run the solver C 4 2 Results Figure C 4 2 shows the computed total transmission and reflection coefficients May 2014 FEKO Examples Guide PERIODIC BOUNDARY CONDITIONS FOR FSS CHARACTERISATION C 4 3 Transmission reflection coefficients Total TXRX Coefficients dB Total reflection coefficient Total transmission coefficient Frequency GHz Figure C 4 2 The transmission and reflection coefficients for the specified incident plane wave May 2014 FEKO Examples Guide Chapter D EMC analysis cable coupling SHIELDING FACTOR OF A SPHERE WITH FINITE CONDUCTIVITY D 1 1 D 1 Shielding factor of a sphere with finite conductivity Keywords shielding EMC plane wave near field finite conductivity FEM A hollow sphere is constructed from a lossy metal with a given thickness An incident plane wave is defined between the frequencies of 1 100 MHz Near fields calculated at the centre of the sphere are used to compute the shielding factor of the sphere The results are compared to values from the literature for the case of a silver sphere with a thickness of 2 5 nm Figure D 1 1 shows a 3D view of the sphere and the plane wave excitation in the CADFEKO model Figure D 1 1 A 3D view of the sphere with a plane wave excitation D 1 1 Finite conductivity sphere MoM Creating the m
91. ded_filter e Set the region properties of the substrate region to substrate and the remaining of the region inside the shielding box to air e Set the solution method for the regions to FEM May 2014 FEKO Examples Guide A MICROSTRIP FILTER E 1 3 e Ensure that the face properties of the microstrip line the face defining the ground below the substrate as well as all of the outside faces of the shielding box are set to PEC e Select a continuous frequency from fmin to fmax The FEM line port is used to define the excitation points for this model Add FEM line ports to Feedi and Feed2 One of the line ports is shown in Figure E 1 2 The ports are labeled Port and Port2 Figure E 1 2 A zoomed in 3D view of one of the FEM current source excitations applied to a line port Requesting calculations The solution requests are e Create an S parameter request where Port1 is active with a 50 Q reference impedance Port2 should be added but not be active Meshing information Use the standard auto mesh setting CEM validate After the model has been meshed run CEM validate Take note of any warnings and errors Correct any errors before running the FEKO solution kernel E 1 2 Microstrip filter on a finite substrate SEP Creating the model The model is based on the FEM model described above In order to use the SEP we must change the meshing no volume mesh elements are required and the excitation method must be ad ju
92. del The results shown in Figure A 10 2 indicate that the model is a good approximation of the full SEP model If one increases the size of the finite substrates the results are expected to converge even more as the infinite plane approximation becomes more appropriate Figure A 10 3 shows the far field at broadside over frequency The far fields are the same shape and the centre frequency deviates by less than 1 May 2014 FEKO Examples Guide MODELLING AN APERTURE COUPLED PATCH ANTENNA A 10 6 Excitation Finite SEP Infinite aperture elements Figure A 10 2 Smith chart showing the reflection coefficient over frequency for the two models Realised Gain Finite SEP Infinite aperture elements N w A Realised gain 2 10 2 12 2 14 2 16 2 18 2 20 2 22 2 24 2 26 2 28 2 30 Frequency GHz Figure A 10 3 Far field realised gain over frequency 0 0 0 May 2014 FEKO Examples Guide DIFFERENT WAYS TO FEED A HORN ANTENNA A 11 1 A 11 Different ways to feed a horn antenna Keywords horn waveguide impressed field pin feed radiation pattern far field A pyramidal horn antenna with an operating frequency of 1 645 GHz is constructed and sim ulated in this example Figure A 11 1 shows an illustration of the horn antenna and far field requests in CADFEKO Figure A 11 1 A pyramidal horn antenna for the frequency 1 645 GHz In particular we want to use t
93. domain Fourier transform A conducting body is placed in the path of an incident plane wave The effect of this obstacle on the plane wave is analysed in the time domain The frequency domain results are first obtained using a wide band simulation using traditional MoM techniques Post processing analysis of the frequency domain data is then performed to obtain a time response Figure G 1 1 shows the obstacle along with the time response of the field and current components at a given time step a Figure G 1 1 Obstacle and time domain results in the 3D view G 1 1 CADFEKO Creating the model The steps for setting up the model are as follows e Define the following variables d 1 Length of the side of the cube obstacle e Create a cuboid whose centre is at the origin and has a side length d e Define a plane wave excitation with an incident direction of 9 75 and 45 e A list of discrete frequency points will be used during the simulation Import the list of discrete frequency points from the file called frequency_list txt this will define an arbitrarily sampled frequency span between 2 5 300 MHz Requesting calculations Geometric symmetry may be applied to all three symmetry planes All surface currents should be calculated A near field with the following properties should be requested May 2014 FEKO Examples Guide TIME ANALYSIS OF THE EFFECT OF AN INCIDENT PLANE WAVE ON AN OBSTACLE G 1 2 e Start
94. e aperture e Subtract aperture from ground Note that the ground plane remains but with a hole in the centre where the aperture plate was defined Rename this to slotted_ground e Create the patch antenna using a plate with its centre at 0 0 d_b a width of patch_w and a depth of patch_1 Label the plate patch e Create the microstrip feed line using a plate with a base corner at feed_w 2 feed_l stub_1 d_a a width of feed_w and a depth of feed_1 Label the plate feed e To excite the model an edge feed will be used A plate is created that connects the ground plane to the microstrip line at the farthest edge of the feed This plate is then split in two parts one for the positive and negative terminals of the excitation Create the feed port by using a plate The origin of the workplane sits at feed_w 2 feed_1 2 stub_1 d_a Rotate the workplane by 90 around the U axis so that the plane where the plate will be created is the vertical X Z plane and is located at the end of the microstrip line The base corner of the plate is at 0 0 0 has a width of feed_w and a depth of d_a Label the plate feedPort The feed port must still be split into the positive and negative terminals Use the split command Split feedPort in the UV plane at 0 0 d_a 2 Rename the two resulting components to port_bottom and port_top May 2014 FEKO Examples Guide MODELLING AN APERTURE COUPLED PATCH ANTENNA A 10 3 e At thi
95. e coupling assuming a matched load To make the results directly comparable the helix antenna in the full model is loaded with the complex conjugate of its input impedance The power loss in the applied load represents the total power received by the antenna This can be found in the out file B 2 4 Results As coupling parameters cannot be computed directly when using the ideal receiving antenna the coupling information must be derived from received power information In POSTFEKO the May 2014 FEKO Examples Guide ANTENNA COUPLING USING AN IDEAL RECEIVING ANTENNA B 2 6 received power may be plotted on a graph or found in the text based output of the out file On the same graph the power lost in the matching load from the full model may be plotted As we have chosen the radiated power to be exactly 100 W for all cases the coupling can be calculated from Received power Coupling ag 10 log10 o The comparative results are shown in Table B 2 1 Received power mW Coupling dB Runtime s Full model 3 2296 44 91 140 370 Receiving antenna far field pattern 3 0477 45 16 lt 13 Receiving antenna spherical modes 3 0735 45 12 lt 13 Receiving antenna near field 2 9418 45 31 lt 13 Table B 2 1 Coupling results with 100 W transmitted power The power loss computed in the full model is shown in this extract from the output file named Antenna_Coupling_Full out POWER LOSS
96. e dipole line primitive by entering the following 2 points d 0 h 2 d 0 h 2 e Create the plate by first rotating the workplane 90 degrees around the V axis May 2014 FEKO Examples Guide DIPOLE IN FRONT OF A PLATE A 3 2 e Create the rectangle primitive by making use of the following rectangle definition method Base centre width depth Enter the centre as 0 0 0 and the width 2 a and depth 2 a e Add a segment port on the middle of the wire e Add a voltage source to the port 1 V 0 50 Q e Set the total source power no mismatch to 1 W e Set the frequency to c0 3 We chose lambda as 3 m e The model contains symmetry and 2 planes of symmetry may be added to accelerate the solution A magnetic plane of symmetry is added on the y 0 plane and an electric plane of symmetry on the Z 0 plane Requesting calculations The solution requests are e Create a horizontal cut of the far field 0 lt lt 360 0 90 Meshing information Use the standard auto mesh setting with the wire radius set to rho CEM validate After the model has been meshed run CEM validate Take note of any warnings and errors Correct any errors before running the FEKO solution kernel A 3 2 Dipole and a plate using HOBF MoM Creating the model The model is identical to the traditional MoM model The only change that is required is to enable HOBF functions for the solution HOPF is activated by navigating to the Solver se
97. e of any warnings notes and errors Please correct error before running the FEKO solution kernel Save the file as feedNetwork cfx and run the solver The S parameters can be displayed in POSTEFEKO this should illustrate that the branch coupler is working correctly split power evenly and 90 phase difference between the output ports A Touchstone file containing the calculated S parameters will be located in the project directory named feedNetwork s3p E 4 2 Patch with non radiating feed network We have simulated and characterised the feed network for the patch antenna in the previous example The result Touchstone file from that simulation is now going to be combined with the patch antenna by using a general non radiating network May 2014 FEKO Examples Guide SUBDIVIDING A MODEL USING NON RADIATING NETWORKS E 4 3 Creating the model The steps for setting up the model are as follows e Define a new dielectric named RogersDuroid5870 Relative dielectric constant of 2 2 and tan 0 0012 e Add an planar multilayer substrate infinite plane with a height of 2 5 mm and dielectric material RogersDuroid5870 An perfect electric ground should be placed on the bottom of the substrate this is the default e Create the rectangular patch antenna at the origin with a patch width of 39e 3 e Create the slots in the patch where the feed is connected by creating and then subtracting two polygonal plates The length of the rectangula
98. e wider than 1 30 of a wavelength This means that strictly speaking the microstrip port should not be wider than about 3 mm Figure A 8 4 A 3D representation of an edge fed microstrip patch antenna on an infinite ground The modification is as follows e Copy the patch from the antenna e Delete the antenna geometry so that only the patch remains May 2014 FEKO Examples Guide MICROSTRIP PATCH ANTENNA A 8 5 e Create a rectangle using the base corner width depth method with the base corner at lengthX 2 feedlineWidth 2 0 The width of the line should be lambda 4 and the depth should be feedlineWidth Label the part feedline e Union all the elements e Add a microstrip port at the edge of the feed line e Add a voltage source on the port 1 V 0 50 Q All meshing and calculation requests can remain the same as in the previous example Run the CEM validate A 8 5 Comparison of the results for the different models The far field gain patterns for all 4 antenna models at 3 GHz are plotted on the same graph in Figure A 8 5 The model with the finite ground should be the best representation of an antenna that can physically be manufactured but the simulation time compared to the infinite plane solution is considerably longer We can also see how the different feeding mechanisms impact the radiation pattern 300 270 240 Pin feed finite ground MoM Pin feed infinite ground MoM Mircostip feed
99. eag ean qoutes 1 1 1 application antenna analysis A 1 1 A 4 1 A 5 1 A 7 1 A 8 1 A 9 1 A 11 1 A 12 1 D 4 1 E 3 1 H 1 1 H 3 1 antenna optimisation A 6 1 antenna placement B 1 1 cable analysis cece cece eens D 2 1 EMG wacicctecrpncds cnt ee pint D 1 1 D 2 1 D 3 1 exposure analysis 2 0000 F 1 1 lens antenna 0 cece eee eee eee A 13 1 microstrip coupler analysis E 5 1 microstrip filter analysis E 1 1 SAR aeee aa a a une a te F 1 1 time domain analysis G 1 1 waveguide analysis E 2 1 H 4 1 application automation FORMS 5 etsene Se tensedens eens denne even I 1 1 POSTEEKO acc ieeciodpaedes renio dpe ri rire I 1 1 TIY sscidsscsdee diese dsceawecsaweceaweeee d A 7 1 B Dirdeaee 2 cose redna cates swine setae sete sotees F 2 1 C cable analysis nuesennnnnnnnnnnnn en D 2 1 cable modelling e eee ee eee D 2 1 CRIB 2435048 E E ete aievedieieasauwares B 1 1 characteristic modes 000000 A 15 1 continuous frequency eee eee ee H 1 1 coupling B 1 1 B 2 1 B 3 1 D 2 1 CUITENE sego obs Geebade ebe gees O GEE EEE A 4 1 D dielectric losses ws idee de ee ad wadee ease sas F 1 1 dielectric resonator antenna DRA A 12 1 dielectric solid 00005 A 2 1 C 2 1 dielectric substrate
100. eans of gaining insight into the time domain behaviour of a system Figure G 1 3 shows the time response of the system to the Gaussian and triangular pulses after 19 ns Figure G 1 3 Time response to the Gaussian pulse left and triangular pulse right after 19 ns Time results can also be analysed on graphs Figure G 1 4 shows the time response of the near field magnitude at 2 2 0 m to both input signals May 2014 FEKO Examples Guide TIME ANALYSIS OF THE EFFECT OF AN INCIDENT PLANE WAVE ON AN OBSTACLE G 1 4 Time responses 1000 900 Response to Gaussian pulse Response to triangular pulse 800 700 600 500 400 E Field mV m 300 200 100 0 10 20 30 40 50 60 70 80 90 100 Time ns Figure G 1 4 E Field Magnitude X position 2 m Y position 2 m Z position 0 m May 2014 FEKO Examples Guide Chapter H Special solution methods A FORKED DIPOLE ANTENNA CONTINUOUS FREQUENCY RANGE H 1 1 H 1 A Forked dipole antenna continuous frequency range Keywords ADAPTFEKO continuous sampling We will consider the input admittance of a simple forked dipole as shown in Figure H 1 1 This example is based on the paper Efficient wide band evaluation of mobile communications antennas using Z or Y matrix interpolation with the method of moments by K L Virga and Y Rahmat Samii in the IEEE Transactions on Antennas and Propagation vol 47 pp 65 76 January
101. ect of all the other patch elements taken into account and also for the 10 x 10 element array We can see that the gain for the element array is about 10 dB higher than the single element Broadside Gain Element phase shift 10x10 Array phase shift e Element squint angle 20 10x10 Array squint angle Gain dBi Theta deg Figure A 16 2 The far field gain for a single element and for a 10 x 10 element 2D array of pin fed patch elements in the broadside direction Figure A 16 3 shows the far field gain for the 20 squint angle models of a single patch element with the effect of all the other patch elements taken into account and also for the 10 x 10 ele ment array May 2014 FEKO Examples Guide PERIODIC BOUNDARY CONDITIONS FOR ARRAY ANALYSIS A 16 5 Gain 20 Squint _ Element phase shift 20l 10x10 Array phase shift e Element squint angle 10x10 Array squint angle N Gain dBi Theta deg Figure A 16 3 The far field gain for a single element and for a 10 x 10 element 2D array of pin fed patch elements in the 20 degree squint direction May 2014 FEKO Examples Guide FINITE ARRAY WITH NON LINEAR ELEMENT SPACING A 17 1 A 17 Finite array with non linear element spacing Keywords finite array DGFM The finite array that is presented here consists of identical array elements
102. ed RogersDuroid5870 Relative dielectric constant of 2 2 and tan 6 0 0012 May 2014 FEKO Examples Guide SUBDIVIDING A MODEL USING NON RADIATING NETWORKS E 4 2 e Add an planar multilayer substrate infinite plane with a height of 2 5 mm and dielectric material RogersDuroid5870 A perfect electric ground should be placed on the bottom of the substrate this is the default e Create the branch coupler for an output impedance of 120 Q e Create the microstrip transmission line sections that connect the branch coupler to the patch antenna This model does not contain the antenna but later this model is imported into the antenna model to do the complete simulation e Create four microstrip ports on the four terminals of feed structure Name the ports by number 1 to 4 starting at the input port then the two output ports that will connect to the patch and then the last port that will be loaded with a resistance e Add a 120 load on fourth port e Set the solution frequency to be from 0 8 2 4e9 to 1 2 2 4e9 Activate the Specify sampling for exported data files and set the value to 100 Requesting calculations Add an S parameter request for port one to three not the port with the load connected All ports should be active and the reference impedance should be set to 120 2 Meshing information Set the local mesh settings of the faces to w1 CEM validate After the model has been meshed run CEM validate Take not
103. elds The calculated near field is normalised to the maximum field value of the standard so that a value of 1 corresponds to the maximum threshold a value of 0 8 corresponds to 80 of the maximum threshold and so on This means that the safety zones can be visualised easily and the safety zones can be determined standards The definitions for the standards are given in Tables D 4 1 and D 4 2 Table D 4 1 Definition for electric and magnetic field limits according to INIRC 88 between 0 4 2 0 GHz Field Type Defintion f in MHz Unit Electric field af Magnetic field 0 008 f BI gt B I lt Table D 4 2 Definition for electric and magnetic field limits according to NRPB 89 between 0 4 2 0 GHz Field Type Defintion F in GHz Unit Electric field 97 1 F Magnetic field 0 258 F A May 2014 FEKO Examples Guide ANTENNA RADIATION HAZARD RADHAZ SAFETY ZONES D 4 5 Create a dataset containing the standards formulae for reference standards pf DataSet New standards Axes Add pf Enums DataSetAxisEnum Frequency pf Enums FrequencyUnitEnum Hz 400e6 1 5e9 21 standards Quantities Add E_inirc88 pf Enums DataSetQuantityTypeEnum Scalar V m standards Quantities Add E_nrpb89 pf Enums DataSetQuantityTypeEnum Scalar V m standards Quantities Add H_inirc88 pf Enums DataSetQuantityTypeEnum Scalar A m standards Quantities Add H_
104. ength of stub at the end of the cross stubWidth armWidth Width of stub at the end of the cross fmin 2e9 The minimum frequency May 2014 FEKO Examples Guide PERIODIC BOUNDARY CONDITIONS FOR FSS CHARACTERISATION C 4 2 fmax 12e9 The maximum frequency e Set the model unit to millimetres mm e Create a rectangle centred at the origin with a width of armWidth and a depth of armLength This rectangle is the main arm of the cross e Create a rectangle at the origin with a width of stubLength and a depth of stubWidth e Translate the stub rectangle to be flush with the end of the arm e Copy and mirror the stub so that there is a stub at each end of the arm e Union the three rectangles e Copy and rotate the structure by 90 e Union and simplify the parts e Set a single plane wave to excite the model with 0 0 and 0 e Set a continuous frequency range from fmin to fmax Requesting calculations Create a single transmission reflection coefficient request leave the phase origin at 0 0 0 Set the periodic boundary condition in two dimensions The following points should be used e Start point d 2 d 2 0 e End point of first vector d 2 d 2 0 e End point of second vector d 2 d 2 0 Determine the phase shift based on the incident plane wave direction Meshing information Use the standard auto mesh setting CEM validate After the model has been meshed run CEM vali
105. entre at the origin Label the wire Dipole e Add a wire port to the centre of the wire Label the port Port1 May 2014 FEKO Examples Guide USING A NON RADIATING NETWORK TO MATCH A DIPOLE ANTENNA E 3 2 e Set the frequency to be continuous over the frequency from fmin to fmax e Create a general network Label it MatchingNetwork The network name should then correspond to the internal network name used in Match ci rcuit cir e Port 1 of this general network is excited using a voltage source excitation The second port is connected to the wire port in the centre of the wire The file Match_circuit cir contains Matching circuit SUBCKT MatchingNetwork ni n2 c1 n1 0 2 376pF 11 ni n2 40 80nH ENDS NWN1 end Requesting calculations No solution requests are required in CADFEKO Meshing information Use the standard auto mesh setting with wire segment radius wireRadius CEM validate After the model has been meshed run CEM validate Take note of any warnings and errors Correct any errors before running the FEKO solution kernel Save the file and run the solver E 3 2 Dipole matching using a general s parameter network Use the same model as for the SPICE matching network model Change the general network settings to refer to an S matrix Touchstone file named Matching s2p This file defines the S parameters of the matching network Port 1 of this general network is ex cited using a voltage source
106. ents are indicated by the geometry colouring based on the legend colour scale This allows identification of points where the current is concentrated The surface currents are displayed in decibels The phase evolution of the current display may be animated as with many other results displays in POSTFEKO on the Animate tab on the ribbon Surface current dBA m Wire curre nt mA 0 0 Figure A 4 4 3D view of the current on the ground plane of the monopole antenna May 2014 FEKO Examples Guide YAGI UDA ANTENNA ABOVE A REAL GROUND A 5 1 A 5 Yagi Uda antenna above a real ground Keywords antenna Yagi Uda antenna real ground infinite planar Green s function optimi sation In this example we consider the radiation of a horizontally polarised Yagi Uda antenna consisting of a dipole a reflector and three directors The frequency is 400 MHz The antenna is located 3 m above a real ground which is modelled with the Green s function formulation Note that the model provided with this example includes a basic optimisation The optimisation is set up such that the optimal dimensions of the antenna may be determined to achieve a specific gain pattern maximise the forward gain and minimise back lobes i gt Figure A 5 1 A 3D view of the Yagi Uda antenna suspended over a real ground A 5 1 Antenna and ground plane Creating the model The steps for setting up the model are as follows e Define the following v
107. eometry for the apertures by creating two rectangles Place the base corner of aperture_1 at d2 2 s 2 0 The aperture is a square with side length s Place the base corner of aperture_2 at d2 2 st d1 s 2 0 The aperture is a square with side length s e Subtract the two apertures from the ground plate The result is a ground plane between the two microstrip lines that has two square holes cut into it e Copy and mirror all geometry around the VN plane e Union all geometry Explicitly set the properties of all of the faces to be perfect electric conductors e Add edge ports to each of the feed faces May 2014 FEKO Examples Guide A MICROSTRIP COUPLER E 5 3 Porti1 Defined between the bottom microstrip feed in the negative X direction and the ground plate that it connects to Port2 Defined between the bottom microstrip feed in the positive X direction and the ground plate that it connects to Port3 Defined between the top microstrip feed in the negative X direction and the ground plate that it connects to Port4 Defined between the top microstrip feed in the positive X direction and the ground plate that it connects to e Create the substrate layers by using two cuboids The top layer has a base centre at the origin a width of substrate_width depth of substrate_depth and a height of substrate_height The bottom layer is the same but has a base centre at 0 0 substrate_height e
108. es A 4 1 D 3 1 far field A 1 1 A 3 1 A 4 1 A 11 1 A 12 1 Pali epee cette eects agi mist a A 5 1 input impedance A 1 1 A 12 1 A 14 1 E 1 1 RADH Z saicisics ssavsitien oteaisse aie dises ance ecw areca Yra D 4 1 radiation pattern A 1 1 A 4 1 A 6 1 RCS Radar cross section DIStATIC ices diet aedensceetedaete vae ece C 2 1 monostatic eee eee eee ees C 2 1 RCS radar cross section DISTING sisaricis anvecaavrrnaavvanaantes maddie C 1 1 MOMNOStAtIC eee eee eee eee H 2 1 reflection coefficient A 9 1 E 1 1 S parameters B 1 1 E 1 1 E 2 1 E 3 1 E 4 1 E 5 1 H 4 1 S S parameters cece ee eee E 3 1 E 4 1 SAR erie ciuttecud ee eud ee AE EE E F 1 1 SCHIPLNS cs vc dvvedeevadewuddebaedeauednebee 1 1 1 shielded cable 0 cc cece cece e eee D 2 1 shielding scsebae obeee cdeee dae deans D 1 1 D 3 1 Skin enei erreira aad owlaed ealad evade Sedan doees D 1 1 Smith Cart 452 0 36 sede Seeds Seeds Seeds Seedase A 9 1 solution method DGFM 0 cece cece cece een cece nes A 17 1 BD ED shi nteretale eos wle eek s A 3 1 A 8 1 E 5 1 FEM MOM ceeececeeeceeeeesees F1 1 geometrical optics 06 A 13 1 infinite planar Green s function A 5 1 A 9 1 A 12 1 method of moments A 1 1 A 2 1 D 1 1 F 2 1 MLFMM eee neces B 1 1 H 2 1 MON a siacasavssnasca ous revssca overeuaycarnrersvacavere sraainews A 3 1 MOM GO cece
109. etallic disk with centre of the disc at the origin with radius patch_rad e Create a rectangle with the definition method Base corner width depth Set the Base cor ner as the following line_width 2 0 substrate_d 2 Set the width line_width and depth line_len May 2014 FEKO Examples Guide PROXIMITY COUPLED PATCH ANTENNA WITH MICROSTRIP FEED A 9 2 e Adda planar multilayer substrate The substrate is substrate_d thick and is of substrate material type with a bottom ground plane Layer0 is of type free space e Create a microstrip port on the edge of the feed line furthest away from the patch element e Add a voltage source to the port e Request that the continuous frequency range is calculated from f_min to f_max Meshing information A single plane of magnetic symmetry is used on the X 0 plane Use the standard auto mesh setting but play around with the curvature refinement options on the advanced tab of the mesh dialog While changing these settings around create the mesh and investigate the effects of the different settings Also investigate the difference in the results this illustrates the importance of performing a mesh conversion test for your model No calculation requests are required for this model since the input impedance is available when a voltage excitation has been defined CEM validate After the model has been meshed run CEM validate Take note of any warnings and errors Correct any errors
110. fm and or opt files have to be generated by opening and re saving the provided project files cfx before the computation of the results can be initiated by running the FEKO preprocessor solver or optimiser FEKO can be used in one of three ways The first and recommended way is to construct the entire model in the CADFEKO user interface The second way is to use CADFEKO for the model geome try creation and the solution set up and to use scripting for advanced options and adjustment of the model for example the selection of advanced preconditioner options The last way is to use the scripting for the entire model geometry and solution set up In this document the focus is on the recommended approaches primarily using the CADFEKO user interface with no scripting Examples that employ only scripting are discussed in the Script Examples guide These exam ples illustrate similar applications and methods to the examples in the Examples guide and it is highly recommended that you only consider the Script Examples if scripting only examples are specifically required It is advisable to work through the Getting started guide and familiarise yourself with the Working with EDITFEKO section in the FEKO Users Manual before attempting the scripting only examples Running FEKO LITE FEKO LITE is a lite version of the FEKO Suite which is limited with respect to problem size and therefore cannot run all of the examples in this guide For more inform
111. following variables freq 10e9 Centre frequency lambda c0 freq 1e3 Free space wavelength in millimetres n 1 Feed pin position index pin_step_size lambda 32 Distance between pin positions pin_length 0 9 lambda 4 Length of pin feed monopole pin_offset pin_step_size n Pin offset from waveguide tip radius 0 1 Radius of pin wires waveguide_length lambda 2 Length of waveguide section wr90_height 10 16 Waveguide height for WR90 X Band wr90_width 22 86 Waveguide width for WR90 X Band e Create a cuboid labelled waveguide It is created with the Base centre width depth height definition method The base centre is at 0 0 0 and with May 2014 FEKO Examples Guide OPTIMISE WAVEGUIDE PIN FEED LOCATION H 4 2 width wr90_width depth waveguide_length height wr90_height e Set the region of the waveguide to free space e Create lines that will be used to imprint vertices on the mesh Create a line labelled imprinted_edge_1 starting at 0 waveguide_length 2 0 and ending at 0 waveguide_length 2 pin_step_size 0 Copy and translate the line from 0 0 0 to 0 2kpin_step_size 0 a number of 7 times e Union all geometry and label it waveguide_perforated e Activate NGF and set waveguide_perforated as a static part You ll see the NGF icon in the tree next to the part It will prevent any changes to the static part of the model e Create
112. g information e Use the standard auto mesh setting e Wire segment radius radius May 2014 FEKO Examples Guide DIPOLE IN FRONT OF A CUBE A 2 3 A 2 3 Dipole and dielectric cube The calculation requests are the same as in the previous model Extending the model The model is extended with the following steps performed sequentially e Create a dielectric medium called diel and relative permittivity of 2 e Set the region of the cuboid to diel e Set the face properties of the cuboid to default This means that CADFEKO will decide the face medium based on the geometry e Delete the lossy_metal metallic medium Meshing information e Use the standard auto mesh setting e Wire segment radius radius CEM validate After the model has been meshed run CEM validate Take note of any warnings notes and errors Please correct error before running the FEKO solution kernel A 2 4 Comparison of the results The gain in dB of all three models are shown on a polar plot in Figure A 2 2 We can clearly see the pronounced scattering effect of the PEC and lossy metal cube with very little difference between their results We also see that dielectric cube has a very different effect The dielectric cube results in an increase in the direction of the cube May 2014 FEKO Examples Guide DIPOLE IN FRONT OF A CUBE A 2 4 PEC e Lossy Metal Dielectric Figure A 2 2 A comparative polar plot of
113. guide port The option to automatically excite the fundamental propagating mode and automatically choose the modes to account for in the solution is used e Symmetry on the X 0 plane may still be used since the excitation is symmetric In addition electric symmetry may be used in the Y 0 plane Meshing information Remesh the model to account for the setting of the local mesh size on the back face of the waveguide CEM validate After the model has been meshed run CEM validate Take note of any warnings and errors Correct any errors before running the FEKO solution kernel A 11 3 Aperture feed Creating the model Here the modal distribution of the TE mode in a rectangular waveguide is evaluated directly in FEKO as excitation for the horn by means of an impressed field distribution on an aperture also see the FEKO User Manual for information on the aperture field source and the AP card This is a far more complex method than using a readily available waveguide excitation but may be useful in certain special cases The application of an aperture field source is supported in CADFEKO but the aperture distribution must be defined in an external file This may be done in many ways but for this example the setup is done by using another CAD FEKO model A waveguide section is created and a near field request is placed inside the wave guide Both the electric and magnetic fields are saved in their respective efe and hfe files
114. he model are considered One method uses a FEM MoM hybrid whilst the other uses a pure MoM approach For the FEM model a layer of air is added to minimise the number of triangles on the FEM MoM interface The antenna geometry including the finite ground plane and a symmetry plane is shown in Figure A 12 1 I MESO Figure A 12 1 Wire frame display of a dielectric resonator antenna on a finite ground plane showing the dielectric resonator and feed pin A 12 1 DRA fed with a FEM modal port Creating the model The steps for setting up the model are as follows e Set the model unit to millimetres e Define variables epsr 9 5 Relative permittivity r 0 63 Feed element radius hBig 1 Feed base height rBig 2 25 Feed base radius rDisk 60 The ground radius 12 5 The inner dome radius rDome rDomeBig rDome 5 5 Outer dome radius h 7 Feed element height fmin 3e9 Lowest calculation frequency fmax 6e9 Highest calculation frequency lambda cO0 fmax 1000 Free space wavelength in millimetres May 2014 FEKO Examples Guide DIELECTRIC RESONATOR ANTENNA ON FINITE GROUND A 12 2 e Define named points excite_b 0 6 5 1 e Create dielectrics Create a dielectric named air with relative dielectric permittivity of 1 and dielectric loss tangent of 0 Create a dielectric named dome with relative dielectric permittivity of epsr and di elect
115. he value for the pin offset which gives the best impedance match to a 50 Q system A 8 1 Pin fed SEP model Creating the model In the first example a feed pin is used and the substrate is modelled with a dielectric with specified dimensions The geometry of this model is shown in Figure A 8 1 A Figure A 8 1 A 3D representation of a pin fed microstrip patch antenna on a finite ground The steps for setting up the model are as follows Note that length is defined in the direction of the X axis and width in the direction of the Y axis e Set the model unit to millimetres e Define the following variables physical dimensions based on initial rough design epsr 2 2 The relative permittivity of the substrate freq 3e9 The centre frequency lambda c0 freq 1e3 The wavelength in free space lengthX 31 1807 The length of the patch in the X direction May 2014 FEKO Examples Guide MICROSTRIP PATCH ANTENNA A 8 2 lengthY 46 7480 The length of the patch in the Y direction offsetX 8 9 The location of the feed substrateLengthX 50 The length of the substrate in the X direction substrateLengthY 80 The length of the substrate in the Y direction substrateHeight 2 87 The height of the substrate fmin 2 7e9 The minimum frequency in the simulation range fmax 3 3e9 The maximum frequency in the simulation range feedlineWidth 4 5 The width of the feedline f
116. his example to compare different options available in FEKO to feed this structure Four methods are discussed in this example e The first example constructs the horn antenna with a real feed pin inside the waveguide The pin is excited with a voltage source Figure A 11 2 Wire pin feed e The second example uses a waveguide port to directly impress the desired mode in this case a TE mode in the rectangular waveguide section Figure A 11 3 Waveguide feed May 2014 FEKO Examples Guide DIFFERENT WAYS TO FEED A HORN ANTENNA A 11 2 e The third example uses an impressed field distribution on the aperture While this method is more complex to use than the waveguide port it shall be demonstrated since this tech nique can be used for any user defined field distribution or any waveguide cross sections which might not be supported directly at the waveguide excitation Note that contrary to the waveguide excitation the input impedances and S parameters cannot be obtained using an impressed field distribution Figure A 11 4 Aperture feed e The fourth example uses a FEM modal boundary The waveguide feed section of the horn is solved by setting it to a FEM region The waveguide is excited using a FEM modal boundary Note that for this type of port any arbitrary shape may be used and the principal mode will be calculated and excited Figure A 11 5 FEM modal port feed A 11 1 Wire feed Creating the model The step
117. iable freq 15 MHz May 2014 FEKO Examples Guide RCS AND NEAR FIELD OF A DIELECTRIC SPHERE C 2 2 Requesting calculations The geometry in this problem is symmetric around all 3 principal planes but the excitation is not As the electric fields of the incident plane wave are purely X directed for the chosen incident angle electric symmetry may be used in the X 0 plane magnetic symmetry may be used in the Y 0 plane but only geometric symmetry may be used in the Z 0 plane The solution requests are e Create a vertical far field request 0 lt lt 180 and 0 e Create a near field request along the Z axis Set the Start position for the near field to 0 0 2 radius and the End position to 0 0 2 radius Request 80 field points in the Z direction Meshing information Use the custom mesh option with the following settings e Triangle edge length 0 2 e Wire segment length Not applicable e Tetrahedral edge length Not applicable e Wire segment radius Not applicable Since the wavelength at the simulation frequency is large compared to the size of the model we need to mesh the model such that it accurately represents a sphere A triangle edge length of 0 2 is fine enough to accurately represent the sphere CEM validate After the model has been meshed run CEM validate Take note of any warnings and errors Correct any errors before running the FEKO solution kernel C 2 2 Results Figures C 2 2 and C
118. ic loss tangent e Create the substrate using the cuboid primitive with the Base corner at 0 0 0 The side lengths are gnd_length and has a height of substrate_height Label the cuboid substrate e Create the shielding box using the cuboid primitive with the Base corner at 0 0 0 The side lengths are gnd_length and it is shielding_height high and label the cuboid shielding _box e Create a cuboid for the microstrip at Base corner port_offset strip_offset 0 The cuboid width is set to gnd_length port_offset 2 a depth of strip_width and with a height of substrate_height Label the cuboid mircostrip e Delete all four vertical faces of mircostrip cube created above e To illustrate the sweep tool the stub will be created by sweeping a line segment Create a line segment that spans from stub_offset strip_offset strip_width substrate_height to stub_offsett strip_width strip_offset strip_width substrate_height Select the line and sweep it from 0 0 0 to 0 stub_length 0 to generate a rect angular patch e Create the following line segments with labels Feed1 and Feed2 Feed1 spans from 0 strip_offset strip_width 2 substrate_height to port_offset strip_offsett strip_width 2 substrate_height Feed2 spans from gnd_length port_offset strip_offsett strip_width 2 substrate_height to gnd_length strip_offset strip_width 2 substrate_height e Union all the geometry and label the union shiel
119. ick on the Global YZ workplane Use the Base corner width depth with the corner at 3 0 0 Set width 6 and depth 3 Set the label to metal_plate e The properties of the rectangle face in the details tree are set so that the UTD method will be applied to the face Meshing information Use the standard auto mesh setting with wire segment radius equal to yagi_rho Requesting calculations e An ideal far field receiving antenna request is created The number of Theta and Phi points is 37 and 73 respectively If changes have been made to the provided models care should be taken to ensure that the number of field points specified for the receiving antenna is consistent with the values stored in the ffe file The pattern file is chosen as the f fe file generated using the free space helix model The origin of the workplane is set to the helix_center named point The U axis direc tion is 1 0 1 to define the orientation of the helix that the pattern represents May 2014 FEKO Examples Guide ANTENNA COUPLING USING AN IDEAL RECEIVING ANTENNA B 2 5 e An ideal spherical mode receiving antenna request is created The spherical mode expansion file is chosen as the sph file generated using the free space helix model The origin of the workplane is set to the helix_center named point The U axis direc tion is 1 0 1 to define the orientation of the helix that the pattern represents Be s
120. ing antenna formulations will be compared to the full solution Note that usually only one of these receiving antennas would be required in a model Figure B 2 1 Geometry of Antenna_Coupling showing full helix model Three models are provided for this example Antenna_Coupling_Helix_Antenna cfx Model of the helix antenna used to pre calculate the far field pattern spherical modes and near field aperture that will be used in the ideal receiving antennas Antenna_Coupling_ Receiving _Antenna cfx The model used to calculate the coupling be tween the Yagi Uda and helix antennas using the ideal receiving antenna techniques Antenna_Coupling_Full cfx The model used to calculate reference result using the full models for both antennas B 2 1 The helix antenna in free space Creating the model The steps for setting up the model are as follows May 2014 FEKO Examples Guide ANTENNA COUPLING USING AN IDEAL RECEIVING ANTENNA B 2 2 e Define variables freq 1 654e9 The design frequency of the helix lambda c0 freq The wavelength in free space n 10 The number of turns for the helix helix_alpha 13 The pitch angle of the helix helix_radius lambdaxcos helix_alpha pi 180 pi 2 The radius of the helix plate_radius 0 75 lambda The radius of the ground plate wire_radius 0 65e 3 The radius of the helix wire segments e An ellipse primitive is used to create a circular plate centred around
121. is comparison May 2014 FEKO Examples Guide DESIGN OF A MIMO ELLIPTICAL RING ANTENNA CHARACTERISTIC MODES A 15 5 Normalised electric far field Characteristic mode 1 Recreated mode 1 Characteristic mode 4 Recreated mode 4 Figure A 15 5 A polar plot comparing the MIMO ring s characteristic electric field modes with the recre ated fields May 2014 FEKO Examples Guide PERIODIC BOUNDARY CONDITIONS FOR ARRAY ANALYSIS A 16 1 A 16 Periodic boundary conditions for array analysis Keywords periodic boundary condition voltage source far field The periodic boundary condition solution method is used to calculate the far field pattern for a single element in an infinite 2D array of pin fed patch elements as well as the approximated far field pattern for a 10 x 10 element array The mutual coupling between elements is taken into account as though the elements were in an infinite array This means that for large arrays the results will be very accurate if edge effects can be neglected z A Figure A 16 1 A 3D view of a single element of the infinite patch array A 16 1 Pin fed patch Broadside pattern by phase shift definition Creating the model The steps for setting up the model are as follows e Define the following variables lambda 0 1 The spacing for periodic boundary condition freq c0 lambda Operating frequency of the patch er 2 55 Relative dielectric constant
122. ive results The required resources memory and CPU time is listed in Table H 3 1 It is clear that the required resources are decreased by using approximations By simply using LE PO as solution method for the reflector the memory requirement and solution time is reduced by several orders of magnitude By sub dividing the model into equivalent source models the resource require ments can be reduced even further The differences in the results is shown in figure H 3 2 and H 3 3 respectively We can see there is excellent comparison between the results Difference observed in the results are due to coupling between the horn and reflector only taken into account for MLFMM solution Although there is no restriction on the size of LE PO triangles the geometry must be accurately meshed For example had a flat plate been used only two triangles would have been required to obtain the same results May 2014 FEKO Examples Guide HORN FEEDING A LARGE REFLECTOR H 3 7 Table H 3 1 Comparison of resources using different techniques for large models Model RAM Time s Total Time s MLFMM benchmark 6 300 Gb 1805 1805 MLFMM Horn PO Reflector 700 Mb_ 4359 4359 MLFMM Horn LE PO Reflector 473 Mb_ 998 998 MoM Horn LE PO Reflector 208 Mb 98 98 Generate AP amp AS source data 20 Mb 36 AP source LE PO Reflector 61 Mb 125 161 Spherical source LE PO Reflector 36 Mb 12 48 Gain dBi F
123. l of right hand side vector 0 020 0 018 Preconditioning system of linear eqns 26 720 26 751 Solution of the system of linear eqns 578 530 578 999 Eigensolution for characteristic modes 0 000 0 000 Determination of surface currents 0 000 0 000 Calcul of impedances powers losses 0 000 0 004 Calcul of averaged SAR values 0 000 0 000 Calcul of power ideal receiving ant 0 000 0 000 Calcul of cable coupling 0 000 0 000 Calcul of error estimates 0 000 0 000 Calcul of electric near field 0 000 0 000 Calcul of magnetic near field 0 000 0 000 Calcul of far field 0 000 0 000 other 6 560 7 106 total times 5863 920 5867 586 total times in hours 1 629 1 630 Peak memory usage during the whole solution 315 522 MByte The S parameters representing the coupling between the antennas mounted on the helicopter and the reflection coefficients of the antennas are shown in Figure B 1 2 as a function of fre quency May 2014 FEKO Examples Guide ANTENNA COUPLING ON AN ELECTRICALLY LARGE OBJECT B 1 3 S parameters dB S parameters dB S parameter S1 1 0 S parameter S2 1 S parameter S3 1 10 20 a a ee 40 50 mm OSSD a ee A eee e ene 60 180 182 184 186 188 190 192 194 196 198 200 Frequency MHz S parameter S1 1 S parameter S2 2 S parameter S3 3 180 182 184 186 188 190 192 194 196 198 200 Frequency MHz Figure B 1 2 The input reflection coeffi
124. l has been meshed run CEM validate Correct any warnings and errors before running the FEKO solution kernel Note that during the FEKO solver run the following warning may be displayed Inhomogeneous segmentation for triangles This warning is due to the occurrence of both very large and small triangles in the rotor of the helicopter This warning may be ignored for this example May 2014 FEKO Examples Guide ANTENNA COUPLING ON AN ELECTRICALLY LARGE OBJECT B 1 2 B 1 2 Results This example requires considerable time to solve as shown in the extract below from the text out file These resource requirements both time and memory for the MLFMM solution are considerably smaller than for the full MoM solution The resource requirements are further reduced in this example by the application of the CFIE formulation to the closed PEC structure of the helicopter In this case the use of the CFIE requires 30 less memory resources and halves the simulation time required when compared with the default EFIE solution SUMMARY OF REQUIRED TIMES IN SECONDS CPU time runtime Reading and constructing the geometry 0 880 0 907 Checking the geometry 0 450 0 451 Initialisation of the Green s function 0 000 0 000 Calcul of coupling for PO Fock 0 000 0 000 Ray launching phase of GO 0 000 0 000 Calcul of the FMM transfer function 12 800 12 812 Fourier transform of FMM basis funct 61 980 62 014 Calcul of matrix elements 5175 980 5178 524 Calcu
125. ld Shielding factor H field 40 35 30 25 Shielding factor dBA m N cos Method of Moments Finite Element Method 0 10 20 30 40 50 60 70 80 90 100 Frequency MHz Figure D 1 3 Shielding of the magnetic field May 2014 FEKO Examples Guide CALCULATING FIELD COUPLING INTO A SHIELDED CABLE D 2 1 D 2 Calculating field coupling into a shielded cable Keywords cable modelling cable analysis shielded cable coupling EMC The coupling from a monopole antenna into a nearby shielded cable that follows an arbitrary path near a ground plane is calculated from 1 MHz to 35 MHz in this example The cable analysis option in FEKO is used for the analysis This method solves the model without the cable first and then calculates the coupling into the cable using the transfer impedance of the cable The same problem could be modelled by by building a full MoM model of the cable but that would be much more resource intensive for complex cables The cable analysis solution also allows the use of a database of measured cable properties integrated into FEKO The geometry shown in Figure D 2 1 consists of a driven monopole antenna and a section of RGS58 shielded cable over an infinite ground plane The RG58 cable is terminated with 50 Q loads at both ends Figure D 2 1 shows the geometry of this model Figure D 2 1 RG58 shielded cable illuminated by a monopole above an infinite ground plane
126. ld optimisation A Jerusalem cross FSS frequency selective surface structure modelled using infinite periodic boundary conditions is excited with an incident plane wave as shown in Figure C 4 1 The frequency dependent transmission and reflection coefficients of the surface are computed and considered These results may be compared to those reported in the literature Ivica Stevanovic Pedro Crespo Valero Katarina Blagovic Frederic Bongard and Juan R Mosig Integral Equation Analysis of 3 D Metallic Objects Arranged in 2 D Lattices Using the Ewald Transformation IEEE Trans Microwave Theory and Techniques vol 54 no 10 October 2006 pp 3688 3697 Note that the model supplied with this example includes an optimisation set up to determine the best set of geometrical parameters to maximise reflection and minimise transmission at 8 GHz To perform the optimisation the frequency request should be set to a single frequency equal to 8 GHz 2 A Figure C 4 1 A 3D view of the FSS structure The Jerusalem cross unit cell structure is shown with the plane wave excitation and periodic boundary condition C 4 1 Frequency selective surface Creating the model The steps for setting up the model are as follows e Define the following variables d 15 2 The spacing for periodic boundary condition armLength 13 3 The length of the arm of the cross armWidth 1 9 The width of the arm of the cross stubLength 5 7 L
127. m dielectric layer epsr_b 2 54 Relative permittivity for the top dielectric layer lambda_a cO f_max sqrt epsr_a 100 Wavelength in the bottom dielectric layer May 2014 FEKO Examples Guide MODELLING AN APERTURE COUPLED PATCH ANTENNA A 10 2 lambda_b c0O f_max sqrt epsr_b 100 Wavelength in top dielectric layer d_a 0 16 Height of bottom dielectric layer d_b 0 16 Height of top dielectric layer patch_1 4 0 Length of the patch antenna patch_w 3 0 Width of the patch antenna grnd_l 2 patch_1 Length of substrate layers and ground plane grnd_w 2 5 patch_w Width of substrate layers and ground plane feed_l lambda_a Length of the microstrip feed line feed_w 0 173 Width of the microstrip feed line stub_1 1 108 Length of the matching stub on the microstrip feed line ap_l 1 0 Length of the aperture 1 ap_w 0 11 Width of the aperture e Set the model units to centimetres e Create a dielectric medium called bottom_layer with relative permittivity of epsr_a and a loss tangent of 0 e Create a dielectric medium called top_layer with relative permittivity of epsr_b and a loss tangent of 0 e Create a ground layer using a plate with its centre at 0 0 0 a width of grnd_w and a depth of grnd_1 Label the plate ground e Create the aperture using a plate with its centre at 0 0 0 a width of ap_1 and a depth of ap_w Label the plat
128. mesh setting with the wire radius set to rho After changing the solution method on the plate to GO the model must be remeshed The triangle sizes are determined by the geometrical shape and not the operating wavelength Unlike the UTD plate the plate will be meshed into triangular elements for the GO CEM validate After the model has been meshed run CEM validate Take note of any warnings and errors Correct any errors before running the FEKO solution kernel A 3 6 Dipole and a PO plate Creating the model The model is identical to the MoM model The only change that is required is that the solution method to be used on the plate must be changed This change is made by going to the face properties of the plate in the detail tree of CADFEKO On the solution tab use the dropdown box named Solve with special solution method and choosing Physical optics PO always illuminated The always illuminated option may be used in this case as it is clear that there will be no shadowing effects in the model With this option the ray tracing required for the physical optics solution can be avoided thereby accelerating the solution Meshing information Use the standard auto mesh setting with the wire radius set to rho The auto mesh feature takes the solution method into account May 2014 FEKO Examples Guide DIPOLE IN FRONT OF A PLATE A 3 5 CEM validate After the model has been meshed run CEM validate Take note of any warning
129. n www lua org pil Another useful resource is the community maintained Wiki that is available on the internet at lua users org wiki For documentation and examples on how to use the automation API see the online help by pressing on the help button in the script editor May 2014 FEKO Examples Guide POSTFEKO APPLICATION AUTOMATION I 1 2 I 1 1 The models Two models are included with this example that will provide the content of the POSTFEKO sessions Assumptions are made about both models For instance e It is assumed that the first configuration will contain 3D far field data e It is assumed that the far field can be wrapped in the direction e It is assumed that there is a angle calculated at p 0 and at 6 90 This also implies that the main direction of radiation is in the positive Z axis Apart from these assumptions any antenna geometry can be used as an input The script can be adapted to iterate over multiple models or to display different properties of interest I 1 2 Exercises As an exercise modify the script from section I 1 3 to e change the rendering of the mesh to be 60 opaque e Automatically generate reports for all of the models in the mode1Name list e Save the sessions under unique names Another exercise that could be useful to try is to reproduce figure I 1 2 It is recommended to write a new script and make use of the documentation for this exercise Export the graph to a pdf file a
130. n above The more conservative slow growth rate was used CEM validate After the model has been meshed run CEM validate Take note of any warnings and errors Correct any errors before running the FEKO solution kernel Note that a warning may be encountered when running the solution This is because losses cannot be calculated in an infinitely large medium as is required for the extraction of antenna directivity information gain is computed by default This warning can be avoided by ensuring that the far field gain be calculated instead of the directivity This is set on the advanced tab of the far field request in the tree A 10 3 Results Using the correct method to model a problem can dramatically decrease runtime and reduce the memory that is required In this case the aperture triangles are used in conjunction with planar multilayer substrates in such a way as to reduce the mesh size of the model This leads to a reduction in resource requirements Table A 10 1 shows the resources that are required for the two models Table A 10 1 Comparison of resources using different techniques for an aperture coupled patch antenna No of RAM MB Time min sec Model Triangles Finite ground Full SEP 3274 343 39 11 11 Infinite ground with aperture triangles 736 4 608 1 57 Table A 10 1 has shown the improvement in resource requirements for running the planar multi layer substrate version of the mo
131. n with a radius of rInU and rInV in the u and v dimensions respectively Set the start and end angles from 0 90 e Select the two curves and create a surface by using the Loft tool Name the quarter ring sector_l May 2014 FEKO Examples Guide DESIGN OF A MIMO ELLIPTICAL RING ANTENNA CHARACTERISTIC MODES A 15 2 Copy and mirror sector_1 around the UN plane Copy and mirror both sectors around the VN plane Union all four sectors to create a single ring structure e Set the simulation frequency to freq e Create four edge ports as indicated Figure A 15 2 Position of the four ports relative to a top view of the ring port_North The port edge should fall on the positive Y axis port_West The port edge should fall on the negative X axis port_South The port edge should fall on the negative Y axis port_East The port edge should fall on the positive X axis Take note that all of the ports point in the same counter clockwise direction Symmetry in general does not apply to characteristic mode analyses since there is no active excitation involved However geometric symmetry can be applied to both the X 0 and Y 0 planes This will result in a symmetrical mesh Configurations Three configurations will be created The first will be to request the characteristic mode analysis The other two configurations will illustrate how one can use the insights obtained from a char acteristic mode analysis to ex
132. nd save the session Normalised Gain Patterns e Hom e Patch 210 150 180 Total Gain Phi 0 deg Figure I 1 2 Gain patterns for both antenna models May 2014 FEKO Examples Guide POSTFEKO APPLICATION AUTOMATION I 1 3 I 1 3 The script generate_antenna_report lua L AUTOMATIC QUICK REPORT GENERATION FOR ANTENNA PATTERN ANALYSIS This script loads the specified model It then creates various views and graphs that display the far field pattern These views are then exported to a PDF report modelName modelName 1 Horn modelName 2 Patch Get user input through Forms form pf Form New Select model comboBox pf FormComboBox New Model name modelName form Add comboBox form Run index comboBox Index app pf GetApplication app NewProject app OpenFile modelName index fek selectedModel app Models modelName index selectedConfigi selectedModel Configurations 1 ffData selectedConfigi FarFields 1 This is a handle on the far field data itself view3D app Views 1 ffPlot view3D Plots Add ffData ffPlot Label ff3D ffPlot Quantity ValuesScaledToDB true view3D_top view3D Duplicate view3D_top SetViewDirection pf Enums ViewDirectionEnum Top view3D_right view3D Duplicate view3D_right SetViewDirection pf Enums ViewDirectionEnum Right view3D_front view3D Duplicate view3D_front SetViewDirection
133. ng would not affect the simulation speed and can be neglected The solution requests are e Create a horizontal far field request labelled H_plane 0 lt lt 180 0 90 and 2 incre ments Meshing information Use the standard auto mesh setting with the wire segment radius equal to r Setting up optimisation e An optimisation search is added with the Simplex method and Low accuracy e The following parameters are set LO min 0 15 max 0 35 start 0 2375 L1 min 0 15 max 0 35 start 0 2265 L2 min 0 15 max 0 35 start 0 22 L3 min 0 15 max 0 35 start 0 22 SO min 0 1 max 0 32 start 0 3 S1 min 0 1 max 0 32 start 0 3 S2 min 0 1 max 0 32 start 0 3 e For this example it is required that the reflector element be longer than all the director elements The following constraints are therefore also defined May 2014 FEKO Examples Guide PATTERN OPTIMISATION OF A YAGI UDA ANTENNA A 6 3 L2 lt L0 L3 lt LO e Two optimisation masks are created see figure A 6 2 The first mask Mask_max defines the upper limit of the required gain gain lt 15 between 0 and 88 gain lt 7 between 90 and 180 The purpose of this mask is to define the region that defines the upper boundary The value of 15 dB in the forward direction was chosen arbitrarily high knowing that this antenna will not be able to achieve 15 dB gain and thus does not have an affect on the optimi
134. nput impedance is automatically calculated for voltage sources Meshing information Use the Standard auto mesh setting with wire segment radius equal to 150e 6 Due to the fine detail in the geometry of the car some advanced mesh settings should be utilised to avoid meshing electrically negligible details On the Advanced tab of the meshing dialog set e the Refinement factor to Coarse e the Minimum element size to Medium Note that a local mesh refinement was set on the windscreen reference face to ensure that the mesh accurately represents the geometry of the face Roughly 5 curvilinear elements is enough to accurately represent the geometry of the windscreen CEM validate After the model has been meshed run CEM validate and ensure that no errors or warnings are reported The Solve Run View by solution parameters dialog can be used to see and ensure that the correct elements have been selected as reference and solution elements A 14 2 Results Save and run the FEKO solver Figure A 14 3 shows the computed input impedance as a function of frequency from 90 110 MHz It is recommended to use MLFMM for simulation at higher frequencies 500 MHz or more May 2014 FEKO Examples Guide WINDSCREEN ANTENNA ON AN AUTOMOBILE A 14 4 Real Imaginary 200 T 150 6 Q g amp 100 f Q 50 0 90 92 94 96 98 100 102 104 106 108 110 Frequency MHz Figure A 14 3 Real and imaginary p
135. nrpb89 pf Enums DataSetQuantityTypeEnum Scalar A m for freqIndex 1 standards Axes pf Enums DataSetAxisEnum Frequency Count do local freqHz standards freqIndex AxisValue pf Enums DataSetAxisEnum Frequency local freqMHz freqHz 1e6 frequency in MHz local freqGHz freqHz 1e9 frequency in GHz local standardsPt standards freqIndex Electric field limits standardsPt E_inirc88 3 math sqrt freqMHz standardsPt E_nrpb89 97 1 math sqrt freqGHz Magnetic field limits standardsPt H_inirc88 0 008 math sqrt freqMHz standardsPt H_nrpb89 0 258 math sqrt freqGHz end return standards INIRC88 This example illustrates how advanced calculations can be performed to display radiation hazard zones The INIRC 88 standards are used nf pf NearField GetDataSet yagi StandardConfiguration1 nf3D function calculateRADHAZThresholds index nf Get a handle on the indexed near field point local nfPt nf index Set up the threshold according to the standards local freq nfPt AxisValue frequency 1e6 Frequency in MHz local EfieldLimit 3 math sqrt freq local HfieldLimit 0 008 math sqrt freq SCALE THE ELECTRIC FIELD VALUES Scale the values to indicate percentages The percentage represents the field value relative to the limit of the standard nfPt efieldcomp1 nfPt efieldcomp1 EfieldLimit nfPt efieldcomp2 nfPt efieldcomp2 EfieldLimit nfPt efieldcomp3 nfPt
136. o define what type of cable is being routed e Create a cable instance that runs from the startConnector and endConnector Connect the two live pins together and the two ground pins together Ensure that the live pins connect to the centre conducting wire and the ground pins connect to the outer shielding of the cable This can be verified by looking at the labels in the preview e Open a schematic view e Add a 50 Q complex load to each connector The load terminates the cable and must be connected between the live and ground pins at each end of the cable e Ensure that the outer shields of the cables i e the ground pins are connected to the global ground in the schematic view Requesting calculations Add a voltage probe over the load terminating the startConnector If the port impedance or power is also of interest then a current probe must also be requested in series to the terminating load The values can then be derived using Ohm s law Meshing information Use the standard auto mesh setting Set the wire radius of the monopole to wireRadius May 2014 FEKO Examples Guide CALCULATING FIELD COUPLING INTO A SHIELDED CABLE D 2 3 CEM validate After the model has been meshed run CEM validate Take note of any warnings and errors Correct any errors before running the FEKO solution kernel D 2 2 Results Results are shown in Figure D 2 2 Voltage over terminating load Voltage dBV 5 10 15 20 25 30 35
137. o which this definition will be applied between the pvb_foil and the bottom glass layer e Select the single face of the windscreen and set its properties so that it is solved using the Windscreen solution method is This is a windscreen reference element and should be displayed in a semi transparent colour that corresponds to the colour of the windscreen definition Keep in mind that windscreen reference elements are not solved with the wind screen solution method but they are use as part of the solution and define the shape and position of the windscreen e Set a local mesh refinement of 0 6 on the windscreen reference face The only require ment for the mesh size is that the geometry should be accurately represented Curvilinear elements are supported for windscreen reference faces and thus only a little refinement is required e Select the wires of the antenna see Figure A 14 2 Set their solution method to be Wind screen These are windscreen solution elements The offset is set to zero so that the solution elements are defined on the reference plane defined above These elements will be solved with the Windscreen e Set the frequency to be continuous from 90 110 MHz Figure A 14 2 Select the wires of the antenna May 2014 FEKO Examples Guide WINDSCREEN ANTENNA ON AN AUTOMOBILE A 14 3 Request calculations We are interested in the input impedance of the antenna and thus no solution requests are re quired The i
138. odel The steps for setting up the model are as follows e Define the following variables r0 1 Radius of sphere f_min 1e6 Lower operating frequency f_max 100e6 Upper operating frequency d 2 5e 9 Thickness of the shell e Silver is a predefined metallic medium in the media library Add the medium to the model e Create a sphere at the origin with radius set equal the defined variable rO e Set the region of the sphere to free space e Set the medium type of the sphere s face to silver and set the thickness equal to the variable d e Create a single incident plane wave with direction set to 0 90 and 180 e Set the frequency to calculate a continuous range between f_min and f_max May 2014 FEKO Examples Guide SHIELDING FACTOR OF A SPHERE WITH FINITE CONDUCTIVITY D 1 2 Requesting calculations In the X 0 plane use geometric symmetry In the Y 0 use magnetic symmetry and in the Z 0 plane use electric symmetry The solution requests are e Create a single point near field request in the centre of the sphere Use the Cartesian coordinate system Meshing information Use the standard auto mesh setting CEM validate After the model has been meshed run CEM validate Take note of any warnings and errors Correct any errors before running the FEKO solution kernel D 1 2 Finite conductivity sphere FEM Creating the model The steps for setting up the model are as follows
139. or the microstrip model feed e Create the patch by creating a rectangle with the base centre width depth definition method Set the width to the defined variable lengthX and depth equal to lengthy Rename this label to patch e Create the substrate by defining a cuboid with the base corner width depth height defini tion method Set the Base corner to substrateLengthX 2 substrateLengthY 2 substrateHeight width substrateLengthX depth substrateLengthY height substrateHeight Rename this label to substrate e Create the feed pin as a wire between the patch and the bottom of the substrate positioned 8 9 mm offsetX from the edge of the patch The pin s offset is in the X direction and should have no offset in the Y direction e Add a segment wire port on the middle of the wire e Add a voltage source on the port 1 V 0 50 Q e Union all the elements and label the union antenna e Create a new dielectric called substrate with relative permittivity equal to epsr e Set region of the cube to substrate e Set the faces representing the patch and the ground below the substrate to PEC e Set a continuous frequency range from fmin to fmax Requesting calculations A single plane of magnetic symmetry is used on the Y 0 plane The solution requests are e Create a vertical E plane far field request 90 lt lt 90 with p 0 and 2 increments e Create a vertical H plane far field request 90 lt 0
140. ows e Create the variables required for the model freq 46 29e6 The operating frequency tau 0 93 The growth factor sigma0 0 7 Spacing lenO 2 Length of the first element dO 0 Position of the first element rado 0 00667 Radius of the first element sigmai sigmai1 sigmaN sigma N 1 tau d1 d11 dN d N 1 sigmaN len1 len11 lenN len N 1 tau radi radi1 radN rad N 1 tau May 2014 FEKO Examples Guide LOG PERIODIC ANTENNA A 7 2 lambda c0 freq Free space wavelength Zline 50 Transmission line impedance Zload 50 Shunt load resistance e Create the twelve dipoles using the defined variables Create line geometry number N from dN lenN 2 0 to dN lenN 2 0 For example to create dipole 1 create a line from d1 len1 2 0 to d1 len1 2 0 e Add a port in the centre of every dipole e Define eleven transmission lines to connect the dipoles Each transmission line has a char acteristic impedance of Zline real part of ZO Ohm and a transmission line length of sigmaN Check the Cross input and output ports to ensure correct orientation of the trans mission line connections e For each segment set the local wire radius equal to the defined radN variable e Connect transmission line N between port N 1 and portN for all of the transmission lines see Figure A 7 2 e Define the shunt load using the admittance definition of a general non radiating network
141. pf Enums ViewDirectionEnum Front polarGraph app PolarGraphs Add ffTracePhi_00 polarGraph Traces Add ffData ffTracePhi_00 IndependentAxis Theta wrapped ffTracePhi_00 Quantity ValuesScaledToDB true ffTracePhi_90 polarGraph Traces Add ffData ffTracePhi_90 IndependentAxis Theta wrapped ffTracePhi_90 Quantity ValuesScaledToDB true ffTracePhi_90 SetFixedAxisValue ffTracePhi_90 FixedAxes 2 90 deg polarGraph ZoomToExtents polarGraph Title Text Gain polarGraph Legend Position pf Enums GraphLegendPositionEnum OverlayTopRight polarGraph BackColour pf Enums ColourEnum LightGrey polarGraph Restore quickReport app CreateQuickReport modelName index AntennaQuickReport pf Enums ReportDocumentTypeEnum PDF quickReport DocumentHeading modelName index Antenna Automated Quick Report quickReport SetPageTitle view3D WindowTitle Isometric View quickReport SetPageTitle view3D_top WindowTitle Top View quickReport SetPageTitle view3D_right WindowTitle Right View quickReport SetPageTitle view3D_front WindowTitle Front View quickReport SetPageTitle polarGraph WindowTitle Theta Cuts quickReport Generate May 2014 FEKO Examples Guide Chapter J Index Index A ADAPTFEKO ocene nonoi nanni nanni ana eases H 1 1 adaptive sampling cece eee ee ee H 1 1 antenna placement eee eee B 1 1 API epee osaga det teased eect a
142. ptimisation search SIMPLEX NELDER MEAD Finished Optimisation finished Goal reached 0 000000000e 00 Optimum found for these parameter 444318132e 01 027415724e 01 316878577e 01 214280613e 01 636975325e 01 3846861767e 01 165823417e 01 iouou it tot ta WNNNNNN Optimum aim function value at no 79 0 000000000e 00 No of the last analysis 79 May 2014 FEKO Examples Guide PATTERN OPTIMISATION OF A YAGI UDA ANTENNA A 6 4 Far field patterns compared to masks 20 oO AF as w oO Original Optimised Minimum Maximum 30 60 90 120 150 180 Phi deg Figure A 6 2 The vertically polarised gain of the Yagi Uda antenna before and after optimisation May 2014 FEKO Examples Guide LOG PERIODIC ANTENNA A 7 1 A 7 Log periodic antenna Keywords Transmission line dipole array far field A log periodic example uses the non radiating transmission lines to model the boom of a log periodic dipole array antenna The antenna is designed to operate around 46 29 MHz with an operational bandwidth over a wide frequency range 35 MHz to 60 MHz Figure A 7 1 shows the log periodic dipole array LPDA with a transmission line feed network Figure A 7 1 The model of LPDA using transmission lines to model the boom structure A 7 1 Log periodic dipole array Creating the model The steps for setting up the model are as foll
143. r field request in the XZ plane with 2 steps for the H plane cut Meshing information Use the coarse auto mesh setting CEM validate After the model has been meshed run CEM validate Take note of any warnings and errors Correct any errors before running the FEKO solution kernel A 11 5 Comparison of the results for the different models The far field gain in dB in the E Plane and H Plane is shown in Figures A 11 6 and A 11 7 respectively May 2014 FEKO Examples Guide DIFFERENT WAYS TO FEED A HORN ANTENNA A 11 7 E Plane Cut FEM Aperture Pin Waveguide Figure A 11 6 Comparison of the far field gain of the horn antenna with different feeding techniques for the E Plane far field request H Plane Cut FEM Aperture Pin Waveguide Figure A 11 7 Comparison of the far field gain of the horn antenna with different feeding techniques for the H Plane far field request May 2014 FEKO Examples Guide DIELECTRIC RESONATOR ANTENNA ON FINITE GROUND A 12 1 A 12 Dielectric resonator antenna on finite ground Keywords dielectric resonator antenna radiation pattern far field input impedance infinite ground FEM current source modal excitation waveguide port The dielectric resonator antenna DRA example illustrates how a coaxial pin feed can be mod elled The input impedance and radiation pattern of a DRA on a finite ground plane are con sidered Two methods for feeding t
144. r polygon is 6 5e 3 and the width 2 8e 3 e Create the inset microstrip feeds by creating rectangular polygons with length 6 5e 3 and width of 1 4e 3 Union the structures to ensure connectivity e Create two microstrip ports on the two feed terminals e Create a new non radiating general network with three ports that imports network proper ties for the Touchstone file created earlier section E 4 1 e Connect the correct microstrip ports to the corresponding network ports e Add a voltage source on the corresponding network port e Set the solution frequency to be from 0 8 2 4e9 to 1 2 2 4e9 Requesting calculations The input impedance at the voltage source is available in POSTFEKO without any requests Adda far field request for a vertical cut Note that no field can exist below an infinite perfect electrically conducting plane The far field request should only be for field points above the infinite plane 85 lt 0 lt 85 with 0 and 5 increments Meshing information The faces of the two microstrip feeds have to be meshed finer than the patch The required mesh size is determined by the size of the geometry Set the local mesh size on these faces to wl The global mesh is set on the Create mesh dialog and should use the standard auto mesh setting Save the file as touchstoneFedPatch cfx and run the solver The input impedance and far field results can be viewed in POSTFEKO May 2014 FEKO Examples Guide SUBDIVID
145. ric loss tangent of 0 Create a dielectric named isolator with relative dielectric permittivity of 2 33 and dielectric loss tangent of 0 e Create a new workplane and place its origin at excite_b Set this workplane as the default workplane e Create a cylinder Set respectively the radius and height equal to rBig and hBig Modify the label to FeedBase e Create another cylinder Set respectively the radius and height equal to r and h hBig Modify the label to FeedPin e Union the two cylinders e Set the region properties of the cylinder FeedPin to the dielectric of type air e Set the region properties of the cylinder FeedBase to the dielectric of type isolator e Set the default workplane back to the global XY plane e Create a disk on the XY plane with the radius set equal to rDisk e Create a sphere with a radius of rDomeBig Set the label to OuterDome e Create a sphere with a radius of rDome Set the label to InnerDome e Union everything and name the unioned part DRA e Delete the bottom halves of both spheres e Set the region of the internal half sphere to be the dielectric named dome e Set the region that is left the space around the internal half sphere to be the dielectric named air e For all the regions set the solution properties to finite element method FEM e Set all of the faces in the model to PEC except the top and bottom faces of the FeedBase the two faces that remain of the sphere
146. rized and positioned at the focal point The E field pattern is described by E cos where 0 lt 0 lt pi 2 is the polar angle measured from the Z axis The pattern data is read from a ffe file with 91 samples and 180 samples in the polar and azimuth angles respectively Far field pattern cuts 0 lt theta lt 180 degree are calculated in the XY plane phi 0 and YZ plane phi 90 The angular increment is set to 0 25 to capture the fine angular detail Meshing requirements Generally the mesh size is determined by the smallest wavelength of interest However when using the Geometrical optics GO ray launching approximation the mesh size is determined by the geometry i e the mesh size is chosen to obtain a reasonable faceted representation of the geometry The run time depends on the number of triangles and it is advisable to not over discretise the geometry For this example the arc length of the spherical arc S1 is used as a basis to determine the mesh size It is also possible to use the standard auto meshing but then the settings on the Advanced tab of the mesh dialog will have to be used to ensure better geometrical approximation CEM validate After the model has been meshed run CEM validate Take note of any warnings and errors Correct any errors before running the FEKO solution kernel A 13 2 Results The results as shown in Figure A 13 2 show the original input gain pattern of the point source
147. rt lwww feko info May 2014 FEKO Examples Guide Chapter A Antenna synthesis analysis DIPOLE EXAMPLE A 1 1 A 1 Dipole example Keywords dipole radiation pattern far field input impedance This example demonstrates the calculation of the radiation pattern and input impedance for a simple half wavelength dipole shown in Figure A 1 1 The wavelength A is 4 m 75 MHz the length of the antenna is 2 m and the wire radius is 2 mm lt gt A Figure A 1 1 A 3D view of the dipole model with a voltage source excitation symmetry and the far field pattern to be calculated in CADFEKO are shown A 1 1 Dipole Creating the model The steps for setting up the model are as follows e Define the following variables lambda 4 Free space wavelength freq cO0 lambda Operating frequency h lambda 2 Length of the dipole radius 2E 3 Radius of the wire e Create a line primitive with the start and end coordinates of 0 0 h 2 and 0 0 h 2 e Define a wire vertex port at the centre of the line e Add a voltage source to the wire port e Set the frequency to the defined variable freq May 2014 FEKO Examples Guide DIPOLE EXAMPLE A 1 2 Requesting calculations This problem is symmetric around the z 0 plane All electric fields will be normal to this plane and therefore the symmetry is electrical The solution requests are e Create a vertical far field req
148. s The model is extended with the following steps performed sequentially May 2014 FEKO Examples Guide MICROSTRIP PATCH ANTENNA A 8 4 Figure A 8 3 A 3D representation of a pin fed microstrip patch antenna on an infinite ground e Delete the substrate component from the antenna geometry e Add a voltage source on the port 1 V 0 50 Q e Add a planar multilayer substrate infinite plane with a conducting layer at the bottom Layer1 must be set to substrate with a height of substrateHeight The meshing values can remain unchanged as the values used for the previous simulation are sufficient Run CEM validate Note that a warning may be encountered when running the solution This is because losses cannot be calculated in an infinitely large medium as is required for the extraction of antenna directivity information gain is computed by default This warning can be avoided by ensuring that the far field gain be calculated instead of the directivity This is set on the advanced tab of the far field request in the tree A 8 4 Edge fed planar multilayer substrate Creating the model This fourth model is an extension of the third model The patch is now edge fed and the mi crostrip feed is used NOTE This example is only for the purposes of demonstration Usually the feed line is inserted to improve the impedance match Also for improved accuracy the edge source width here the width of the line of 4 5 mm should not b
149. s Ensure that higher order basis functions are enabled on the Sover settings dialog The curvilinear elements are a better approximation of the geometry and standard meshing results in an accurate geometrical representation CEM validate After the model has been meshed run CEM validate Take note of any warnings and errors Correct error before running the FEKO solution kernel C 3 2 Results Figure C 3 2 shows the computed scattering width as a function of the bistatic observation angle p for two different cylinder radii The results agree well with the literature reference The scattering width was obtained by using the equation at the top of the example with the values provided to simplify to SW 27500 E To use the equation ensure the magnitude of the electric field is displayed and activate the Enable maths Enter the following equation in POSTFEKO 2 pi 500 ABS self 2 May 2014 FEKO Examples Guide SCATTERING WIDTH OF AN INFINITE CYLINDER C 3 3 Scattering width 1 e Radius 0 1 lambda e Radius 0 6 lambda Scattering width m Phi deg Figure C 3 2 The scattering width of an infinite cylinder with two different radii modelled May 2014 FEKO Examples Guide PERIODIC BOUNDARY CONDITIONS FOR FSS CHARACTERISATION C 4 1 C 4 Periodic boundary conditions for FSS characterisation Keywords periodic boundary condition plane wave frequency selective surface near fie
150. s and the single face inside the FeedPin These should be the default medium May 2014 FEKO Examples Guide DIELECTRIC RESONATOR ANTENNA ON FINITE GROUND A 12 3 e The outer dome can be meshed more coarsely since the geometry is not of any specific interest Set a local refinement of lambda 8 which is equivalent to a coarse mesh size for the MoM boundary between the air region and the surrounding free space e Use the Simplify transform to remove redundant faces and edges in the model e Add a FEM modal port to the bottom face of FeedBase at the bottom of the antenna e Apply FEM modal excitation to the modal port e Set the frequency to be continuous from fmin to fmax Requesting calculations A single plane of magnetic symmetry on the X 0 plane may be used for this model The solution requests are e Create a vertical far field request in the XZ plane 180 lt lt 180 with p 0 and 2 steps Meshing information Use the Coarse auto mesh setting The curvature of the model will cause further refinement to the complex parts of the model to ensure that the geometry is accurately represented CEM validate After the model has been meshed run CEM validate Take note of any warnings and errors Correct any errors before running the FEKO solution kernel A 12 2 DRA fed with a waveguide port Creating the model The steps for setting up the model are as follows e Set the model unit to millimetres
151. s Guide LOG PERIODIC ANTENNA A 7 4 Real Imaginary 50 40 30 20 Impedance Ohm 10 10 20 I 35 40 45 50 55 60 Frequency MHz Figure A 7 4 The input impedance real and imaginary of the LPDA antenna over the operating band May 2014 FEKO Examples Guide MICROSTRIP PATCH ANTENNA A 8 1 A 8 Microstrip patch antenna Keywords microstrip patch antenna dielectric substrate pin feed edge feed optimisation SEP FDTD A microstrip patch antenna is modelled using different feed methods The dielectric substrate is modelled as a finite substrate and ground using the surface equivalence principle SEP as well as a planar multilayer substrate with a bottom ground layer using a special Green s function The simulation time and resource requirements are greatly reduced using an infinite plane although the model may be less representative of the physical antenna The two different feeding methods considered are a pin feed and a microstrip edge feed In this example each model builds on the previous one It is recommended the models be built and considered in the order they are presented If you would like to build and keep the different models start each model by saving the model to a new location Note that the model provided with this example for the pin fed patch SEP on a finite substrate includes a basic optimisation set up The optimisation is defined to determine t
152. s and errors Correct any errors before running the FEKO solution kernel A 3 7 Comparative results The total far field gain of the dipole in front of the PEC plate is shown on a dB polar plot in Figure A 3 2 The MoM UTD MoM PO and full MoM reference solution are shown To obtain the large element PO LE PO models set the solution method from Physical optics PO al ways illuminated to Large element physical optics LE PO always illuminated and save the PO example files under a new name Since the dipole is less than a wavelength away from the plate the standard auto meshing will not work Mesh the plate with a triangle edge length of a 4 Far field MoM amp GO MoM HOBF MoM amp LEPO MoM traditional RWG MoM amp PO MoM amp UTD 270 FDTD 330 Figure A 3 2 A polar plot of the total far field gain dB computed in the horizontal plane using the MoM GO MoM UTD MoM PO MoM LE PO and FDTD methods compared to the full MoM traditional and HOBF reference solution The comparison between memory requirements and runtimes are shown in Table A 3 1 The method of moments MoM is used as reference and all other methods are compared using a memory and runtime factor Requirements for the MoM solution was 10 s and 51 88 MB May 2014 FEKO Examples Guide DIPOLE IN FRONT OF A PLATE A 3 6 Solution method Memory of MoM Runtime of MoM MoM HOPF auto 4 88 140 Physical optics
153. s are e Create a single point near field request in the centre of the sphere Use the Cartesian coordinate system Meshing information Use the standard auto mesh setting CEM validate After the model has been meshed run CEM validate Take note of any warnings and errors Correct any errors before running the FEKO solution kernel D 1 3 Results The subject of interest is the shielding capability of the sphere with respect to the incident electric and magnetic fields In other words we calculate the ratio between the field measured inside the sphere and the field incident on the sphere The incident field strength was set as E 1 V m From the wave impedance for a plane wave in free space the incident magnetic field can be calculated E 1 H 2 6544 x 103A No 376 7 pm The shielding factor is therefore E S 20 loge dB l S 20 dB 20 x log h amp H Figures D 1 2 and D 1 3 show respectively the shielding of the electric and magnetic fields as a result of a sphere with the finite conductivity properties provided May 2014 FEKO Examples Guide SHIELDING FACTOR OF A SPHERE WITH FINITE CONDUCTIVITY D 1 4 Shielding factor E field 70 Method of Moments 60 _ Finite Element Method gt a 3 5 50 iS D Kej 2 40 N 30 0 10 20 30 40 50 60 70 80 90 100 Frequency MHz Figure D 1 2 Shielding of the electric fie
154. s for setting up the model are as follows e Set the model unit to centimetres e Create the following variables freq 1 645e9 The operating frequency lambda c0 freq 100 Free space wavelength wa 12 96 The waveguide width wb 6 48 The waveguide height ha 55 Horn width hb 42 80 Horn height May 2014 FEKO Examples Guide DIFFERENT WAYS TO FEED A HORN ANTENNA A 11 3 wl 30 20 Length of the horn section fl wl lambda 4 Position of the feed wire in the waveguide hl 46 Length of the horn section pinlen lambda 4 56 Length of the pin e Create the waveguide section using a cuboid primitive and the Base corner width depth height definition method The Base corner is at wa 2 wb 2 wl width of wa depth of wb and height of wl e Delete the face lying on the UV plane e Create the horn using the flare primitive with its base centre at the origin using the defini tion method Base centre width depth height top width top depth The bottom width and bottom depth are wa and wb The height top width and top depth are hl ha and hb respectively e Delete the face at the origin as well as the face opposite to the face at the origin e Create the feed pin as a wire element from 0 wb 2 f1 to 0 wb 2 pinlen f1l e Add a wire segment port on wire The port must be placed where the pin and the waveguide meet e Add a voltage source to the port 1 V 0 50 Q e
155. s point all of the PEC parts have been created that are required for the model Union all of the parts and rename the resulting geometry to conducting_elements e Explicitly set the face properties of all of the faces to PEC This ensures that the faces will remain PEC after future union operations e Create the bottom dielectric layer by using a cuboid whose centre is located at 0 0 d_a The cuboid has a width of grnd_w a depth of grnd_1l and a height of d_a Label the cuboid bottom_layer e Create the top dielectric layer by using a cuboid with its base centre at 0 0 0 The cuboid has a width of grnd_w a depth of grnd_1 and a height of d_b Label the cuboid top_layer e Union all of the geometry components e Set the bottom region medium to bottom_layer and the top region medium to top_layer e Ensure that the patch microstrip line the feed port and the ground plate are all set to PEC e Add and edge port between the two split components of feedPort Let the positive face correspond to the face attached to the ground plane Add a voltage source to the port with the default source properties e In order to obtain accurate results whilst minimising resource requirements local mesh refinement is necessary on several of the geometry parts Set local mesh refinement of lambda_b 40 on the patch edges Set local mesh refinement of ap_w 0 7 aperture edges Set local mesh refinement on the feed face to feed_w 2 e Set the
156. sation Upper limit of 7 dB from 90 to 180 will have an effect on the optimisation and determines the size of the back lobes that we are willing to accept The second Mask Mask_min defines the lower limit of the required gain gain gt 8 dB between 0 and 30 gain gt 40 dB between 32 and 180 This mask is used to determine the desired main lobe gain The value of 40 dB outside the main lobe was chosen arbitrarily low and thus will not affect the optimisation Two far field optimisation goals are added based on the H_plane calculation request The dB values 10 x log of the vertically polarised gain at all angles in the requested range is required to be greater than Mask_min and less than Mask_max A weighting for both goals are equal since neither of the goals are more important than the other The weighting that should be used depends on the goal of the optimisation A 6 2 Results The radiation pattern calculated in the E plane of the antenna is shown in Figure A 6 2 for both the initial design and the antenna resultant after the optimisation process The gain in the back lobe region between 90 and 180 degrees has been reduced to around 7dB while the gain over the main lobe region between 0 and 30 degrees is above 8dB Note that the graph shows the vertically polarised gain plotted in dB with respect to The extract below from the optimisation log file indicates the optimum parameter values found during the o
157. sted The steps for modifying the FEM model are as follows May 2014 FEKO Examples Guide A MICROSTRIP FILTER E 1 4 e Delete the S parameter request and both of the line ports including the line geometry used to define the port locations e Set the region properties of the two regions back to MoM MLFMM with surface equivalence principle SEP default Also set the air region back to Free space e As described in the note below we need to create an excitation point inside the dielectric region In order to do this create a face extending from the microstrip edge down to the ground plane just inside the dielectric region as shown in Figure E 1 3 The simplest way to do this is to select and copy the edges at the microstrip line feed points and sweep them down to the ground to create a plate e Split the two feed plates added above in the middle to create a feed edge inside the substrate e Union all the geometry Ensure that all faces are still represented by the correct materials and that no entities have gone suspect e Create the edge port connections as illustrated in Figure E 1 3 e Ensure that the face properties of the microstrip line the ground below the substrate and sides of the substrate are PEC e Set a local mesh size on the microstrip lines faces of strip_width 0 7 NOTE When the edge source is used together with a finite sized dielectric the edge for the port must be surrounded on all sides by
158. sting calculations A single plane of electrical symmetry on the Y 0 plane is used in the solution of this problem The solution requests are e Create a vertical far field request above the ground plane 90 lt lt 90 with 0 and 0 0 5 increments e Set the Workplane origin of the far field request to 0 0 3 Meshing information Use the standard auto meshing option with the wire segment radius equal to wireRadius May 2014 FEKO Examples Guide YAGI UDA ANTENNA ABOVE A REAL GROUND A 5 3 CEM validate After the model has been meshed run CEM validate Take note of any warnings and errors Correct any errors before running the FEKO solution kernel Note that a warning may be encountered when running the solution This is because losses cannot be calculated in an infinitely large medium as is required for the extraction of antenna directivity information gain is computed by default This warning can be avoided by ensuring that the far field gain be calculated instead of the directivity This is set on the Advanced tab of the far field request in the tree A 5 2 Results The radiation pattern is calculated in the H plane of the antenna A simulation without the ground plane is compared with the results from the model provided for this example in Fig ure A 5 2 As expected the ground plane greatly influences the radiation pattern Note that the graph is a vertical polar plot of the gain in dB for the two cases
159. strate model is shown in Figure E 1 1 z A Figure E 1 1 A 3D view of the simple microstrip filter model in CADFEKO A cutplane is included so that the microstrip lines of the filter inside the shielding box are visible E 1 1 Microstrip filter on a finite substrate FEM Creating the model The substrate and shielding box are made using cuboid primitives The microstrip line is built using a cuboid primitive and removing the undesired faces The stub is added by sweeping a line that forms a leading edge of the stub The steps for setting up the model are as follows e Set the model unit to millimetres e Create the following variables fmax 4e9 Maximum frequency fmin 1 5e9 Minimum frequency epsr 2 33 Substrate relative permittivity shielding _height 11 4 Height of the shielding box 1 57 Substrate height substrate_height May 2014 FEKO Examples Guide A MICROSTRIP FILTER E 1 2 gnd_length 92 Length and width of substrate port_offset 0 5 Inset of the feed point strip_width 4 6 Width of the microstrip sections strip_offset 23 Offset of the microstrip from the ground edge stub_length 18 4 Length of the stub stub_offset 41 4 Inset length from the ground edge to the stub e Create a dielectric medium named air with the default properties of a vacuum e Create a dielectric medium named substrate with relative permittivity of epsr and zero dielectr
160. t the Start point and End point as S1 2 lambda 0 L3 lambda and S1 2 lambda 0 L3 lambda respectively e Use a continuous frequency range from fmin to fmax Requesting calculations The Z 0 plane is an electric plane of symmetry A magnetic plane of symmetry exists in the Y 0 plane The solution requests are e Create a 3D Cartesian near field block Start 0 6 0 6 0 6 End 1 2 0 6 0 6 Number of U increments 20 Number of V increments 10 Number of N increments 10 Meshing information Use the standard auto mesh setting with the wire segment radius equal to r May 2014 FEKO Examples Guide ANTENNA RADIATION HAZARD RADHAZ SAFETY ZONES D 4 3 D 4 2 POSTFEKO A session containing the following instructions is provided radiation_zones pfs The ses sion contains the results from the antenna simulation and three script results INIRC88 This script results in a near field result that incorporates the calculated near fields and the INIRC 88 safety standards for occupational limits NRPB89 This script results in a near field result that incorporates the calculated near fields and the NRPB 89 safety standards standards This is a custom dataset that contains both of the standards used here The result can be plotted on a 2D graph and shows the maximum field limits for both magnetic and electric fields over the calculated frequency band Figure D 4 2 shows these results for both the magnetic
161. te a new dielectric medium with the name air and use all the default values of free space e Set the region property of the waveguide to be a dielectric and select air as the dielectric e Ensure that the faces that form the walls of the waveguide are set to PEC Note that the port faces must be dielectrics for FEM ports e Set the solution method of the region to finite element method FEM e Decouple the FEM and MoM the setting is available on the FEM tab of the Solver settings dialog Requesting calculations The solution requests are e An S parameter calculation is requested Fundamental mode for both ports Only Port1 needs to be active Meshing information Use the fine auto mesh setting CEM validate After the model has been meshed run CEM validate Take note of any warnings and errors Correct any errors before running the FEKO solution kernel E 2 3 Results Save and run the FEKO solver Figure E 2 2 shows the computed S parameters with FEKO for both the MoM and the FEM solutions It is clear that the cut off frequency is at about 9 4871 GHz These results agree well with available references both measurements and computations and with one another May 2014 FEKO Examples Guide S PARAMETER COUPLING IN A STEPPED WAVEGUIDE SECTION E 2 4 S parameter Sn MoM diwetaee Sa MoM A Sn FEM 7 So FEM 1 oi S parameters dB a 3s N a 10 11 12
162. that are arbitrarily spaced A pin fed patch antenna serves as the base element for the array The array is created by arbitrarily placing the base element see figure A 17 2 for the array s layout Arrays of this type are difficult to model and can result in high resource requirements It will be shown how the array can be constructed using the available finite array tools When arrays are constructed in this way the DGFM domain Green s function method acceleration can be applied to lower the resources that are needed Figure A 17 1 shows the full 3D far field pattern for the array Total Gain dBi 20 0 Figure A 17 1 The 3D far field pattern for the array A 17 1 Pin fed patch array Creating the model The steps for setting up the model are as follows e Define the following variables freq 2 4e9 Operating frequency of the patch lamO cO0 freq 1000 Free space wavelength in millimetres epsr 2 08 Relative dielectric constant of patch substrate patchLength 41 Length of the patch antenna patchWidth 35 Width of the patch antenna h 3 5 The height of the substrate pinOffset 11 Distance of feed pin from patch centre wireRadius 0 1 Radius of the feed pin wire e Set the model unit to millimetres May 2014 FEKO Examples Guide FINITE ARRAY WITH NON LINEAR ELEMENT SPACING A 17 2 e Create a rectangle centred at the origin with a width of patchWidth and a depth of patch
163. the parabolic dish Start by defining the following variables freq 12 5e9 The operating frequency lam c0 freq Free space wavelength lam_w 0 0293 The guide wavelength h_a 0 51 1lam The waveguide radius h_b0O 0 65 1am Flare base radius h_b lam Flare top radius h_1 3 05x 1lam Flare length ph_centre 2 6821e 3 Horn phase centre R 18 1lam Reflector radius F 25 1am Reflector focal length w_l1 2 lam_w The waveguide length The steps for creating the horn are as follows Create a cylinder along the Z axis with the base centre at 0 0 w_l h_1 a radius h_a and a height w_1 Label the cylinder waveguide Create a cone with a base centre 0 0 h_1 a base radius h_b0 a height h_1 and a top radius h_b Label the cone flare Union the two parts and then simplify the resulting union Rename the new part to horn Delete the face on the end of the horn Rotate the horn with 90 after setting the axis direction to 0 1 0 Set a local mesh size of 1am 20 on the face at the back of the waveguide section Create a waveguide port on the same face Add a waveguide excitation on the waveguide port Excite the fundamental mode use the default settings The horn is now complete The next step is to create the parabolic reflector Create a paraboloid at 0 0 F with radius R and depth F Label the paraboloid reflector Rotate the ref lector with 90 after setting the axis direction to
164. the port located at the junction between the wire and the ground plane If this is not so change the port position between Start and End e Add a voltage source to the port 1 V 0 50 Q e Set the frequency equal to freq May 2014 FEKO Examples Guide A MONOPOLE ANTENNA ON A FINITE GROUND PLANE A 4 2 Requesting calculations Two planes of magnetic symmetry are defined at the x 0 plane and the y 0 plane The solution requests are e A full 3D far field pattern with 2 increments e All currents are saved to allow viewing in POSTFEKO Meshing information e Use the standard auto mesh setting e Wire segment radius wireRadius CEM validate After the model has been meshed run CEM validate A 4 2 Results A polar plot of the total gain in a vertical cut is shown in Figure A 4 2 Gain Theta cut Phi 0 Figure A 4 2 Polar plot of the total gain in a vertical cut The full 3D gain pattern is depicted in Figure A 4 3 Since the antenna has an omnidirectional pattern in the plane the value of can be coarser The far field gain is shown slightly trans parent in the figure to allow for visibility of the geometry and the curve of the far field pattern May 2014 FEKO Examples Guide A MONOPOLE ANTENNA ON A FINITE GROUND PLANE A 4 3 Figure A 4 3 A full 3D plot of the antenna gain The currents on all elements wire segment and surface triangles are shown in Figure A 4 4 The curr
165. to wireRadius CEM validate After the model has been meshed run CEM validate Take note of any warnings and errors Correct any errors before running the FEKO solution kernel H 1 2 Results In order to view the results for this example we create a Cartesian graph and plot the real and imaginary parts of the input impedance of the voltage source The input impedance is plotted in Figure H 1 2 Figure H 1 3 shows the same results over a smaller frequency band May 2014 FEKO Examples Guide A FORKED DIPOLE ANTENNA CONTINUOUS FREQUENCY RANGE H 1 3 Excitation Real Imaginary Admittance mS 100 120 140 160 180 200 220 240 260 280 300 Frequency MHz Figure H 1 2 Real and imaginary parts of the input admittance of the forked dipole Excitation Real Imaginary Admittance mS 202 203 204 205 206 207 208 Frequency MHz Figure H 1 3 Input admittance of the forked dipole around the resonance point May 2014 FEKO Examples Guide USING THE MLFMM FOR ELECTRICALLY LARGE MODELS H 2 1 H 2 Using the MLFMM for electrically large models Keywords MLFMM large model Radar cross section trihedral In this example we consider a single plane wave incident from 9 60 and 0 on a large trihedral The size of the trihedral 13 54 surface area was chosen such that it can still be solved using the standard MoM This example is large enough to demonstrate the
166. tput ports it can be seen that almost all energy incident on the filter at 2 75 GHz is reflected back to the input port The effect of the different solution methods and feed techniques can be seen in the results but all results agree very well with the reference measurements and with each other S14 S parameters dB Fin substrate FEM Inf substrate GF Fin substrate SEP 1 5 2 0 2 5 3 0 3 5 4 0 Frequency GHz Figure E 1 4 S in dB of the microstrip filter on an infinite and finite substrate from 1 5 GHz to 4 GHz May 2014 FEKO Examples Guide A MICROSTRIP FILTER E 1 7 Sa4 S parameters dB Fin substrate FEM Inf substrate GF Fin substrate SEP 1 5 2 0 2 5 3 0 3 5 4 0 Frequency GHz Figure E 1 5 Sj in dB of the microstrip filter on an infinite and finite substrate from 1 5 GHz to 4 GHz May 2014 FEKO Examples Guide S PARAMETER COUPLING IN A STEPPED WAVEGUIDE SECTION E 2 1 E 2 S parameter coupling in a stepped waveguide section Keywords waveguide S parameter coupling In this example we consider a waveguide transition from Ku to X band by a simple step disconti nuity as shown in Figure E 2 1 using two solution methods available in FEKO The model is first simulated using the MoM using waveguide ports and then using the FEM and modal ports The rectangular waveguide dimensions are a 15 8 mm and b 7 9 mm for the Ku band waveguide and a 22 9 mm and b 1
167. ts of a cylindrical section of variable radius and height of half a wavelength at the excitation frequency The cylinder is realised by creating a cylinder primitive and deleting the upper and lower faces of the cylinder Requesting calculations For this example the scattering width of the cylinder for an incident plane wave normal to the cylinder will be considered A plane wave excitation for 0 90 and 180 is used The 1D periodic boundary condition is defined along the axis of the cylinder so that the unit cell touches the edges of the periodic region A near field request is used to determine the direction dependent scattered field from which the scattering width is derived e Request a cylindrical coordinate system near field e Set the radius as p 500 lambda May 2014 FEKO Examples Guide SCATTERING WIDTH OF AN INFINITE CYLINDER C 3 2 e Specify 0 5 angular resolution e It is important to only calculate the scattered part of the near field This removes the effect of the plane wave on the calculated field and ensures that only the scattered fields are considered The calculation is performed at a frequency of 299 8 MHz wavelength of 1 m Meshing information Use the fine auto mesh setting Also try modifying the parameters on the advanced tab to obtain a mesh that better represents the geometry as a cylinder It is also possible and recommended to simulate the same model using higher order curvilinear element
168. ttings dialog on the Solve Run ribbon tab and activating the Solve with higher order basis functions HOBF check box Also ensure the basis function order is set to auto Meshing information Use the standard auto mesh setting with the wire radius set to rho After changing the solu tion method to use HOBE the model must be remeshed since HOBF elements are larger than traditional MoM elements May 2014 FEKO Examples Guide DIPOLE IN FRONT OF A PLATE A 3 3 CEM validate After the model has been meshed run CEM validate Take note of any warnings and errors Correct any errors before running the FEKO solution kernel A 3 3 Dipole and a plate using FDTD Creating the model The model is identical to the traditional MoM model The only change that is required is to enable FDTD by navigating to the Solver settings dialog on the Solve Run ribbon tab Meshing information Use the standard auto mesh setting with the wire radius set to rho After changing the solution method the model must be remeshed to obtain a voxel mesh representation of the geometry CEM validate After the model has been meshed run CEM validate Take note of any warnings and errors Correct any errors before running the FEKO solution kernel A 3 4 Dipole and a UTD plate Creating the model The model is identical to the MoM model The only change that is required is that the solution method to be used on the plate must be changed This change is made
169. uest 180 lt 0 lt 180 with p 0 where 0 and denotes the angles theta and phi Sample the far field at 2 steps Meshing information Use the standard auto mesh setting with wire segment radius equal to radius CEM validate After the model has been meshed run CEM validate Take note of any warnings and errors Correct any errors before running the FEKO solution kernel A 1 2 Results A polar plot of the gain in dB of the requested far field pattern is shown in Figure A 1 2 Under the graph display settings open the advanced dialog in the Axes group Set the maximum dynamic range of the radial axis to 10 dB Gain Figure A 1 2 A polar plot of the requested far field gain dB viewed in POSTFEKO May 2014 FEKO Examples Guide DIPOLE EXAMPLE A 1 3 Since the impedance is only calculated at a single frequency it can easily be read from the out file The OUT file can be viewed in the POSTFEKO out file viewer or in any other text file viewer An extract is shown below DATA OF THE VOLTAGE SOURCE NO 1 real part imag part magnitude phase Current in A 1 0439E 02 4 8605E 03 1 1515E 02 24 97 Admitt in A V 1 0439E 02 4 8605E 03 1 1515E 02 24 97 Impedance in Ohm 7 8729E 01 3 6658E 01 8 6845E 01 24 97 Inductance in H 7 7844E 08 Alternatively the impedance can be plotted as a function of frequency on a Cartesian graph or Smith chart in POSTFEKO May 2014 FEKO Examples Guide DIPOLE
170. ure to use the far field approximation for the internal approximation of the spher ical modes receiving antenna In cases where the request is very close to geometry using spherical modes for the internal approximation may be inaccurate e An ideal near field receiving antenna request is created The near fields files is chosen as the efe and hfe files for electric and magnetic near fields respectively These files were generated using the free space helix model Select the spherical coordinate system The radius should be set to 0 45 The number of Theta and Phi points is 37 and 73 respectively If changes have been made to the provided models care should be taken to ensure that the number of field points specified for the receiving antenna is consistent with the values stored in the efe and hfe files The origin of the workplane is set to the helix_center named point The U axis direc tion is 1 0 1 to define the orientation of the helix that the pattern represents The Yagi Uda antenna is oriented so that its first side lobe is aimed directly at the helix The radiated power is configured as 100 W by selecting the Total source power no mismatch option on the power settings dialog CEM validate After the model has been meshed run CEM validate Take note of any warnings and errors Correct any errors before running the FEKO solution kernel B 2 3 The full model The ideal receiving antenna calculates th
171. user defined parameters e freq 30e9 The operating frequency e lambda_O c0 freq Free space wavelength e D lambda_0 10 Diameter of cylinder e F 1 5 D Focal length e epsr 6 The relative permittivity e tand 0 005 Dielectric loss tangent May 2014 FEKO Examples Guide A LENS ANTENNA WITH GEOMETRICAL OPTICS GO RAY LAUNCHING A 13 2 The following variables derived from the above variables are used in the model construction e alpha arcsin D 2 F Included angle to edge of lens e arclength alpha F Arc length to edge of lens e gLO arclength 10 Mesh variable e n sqrt epsr Refraction index e T 2 F sqrt 4 F D 2 n 1 Lens thickness e v0 F T n 1 Ellipse offset distance e u0 sqrt n 1 vO Ellipse minor axis length e w0 n vO Ellipse major axis length A dielectric medium named Glass is defined and the relative permittivity and loss tangent are set to the variables epsr and tand respectively To construct the lens a sphere will be subtracted from an elliptical spheroid The steps are as follow e Create a sphere at the origin with a radius F e Create a spheroid by choosing the Centre radius U radius V radius N method when creating a sphere Its properties are Centre 0 0 v0 Radius Ru u0 Radius Rv u0 Radius Rn w0 e Subtract the sphere from the spheroid the resulting geometry can be labelled Lens e By default a
172. using the array techniques This will become more evident for arrays that contain a larger number of elements May 2014 FEKO Examples Guide Chapter B Antenna placement ANTENNA COUPLING ON AN ELECTRICALLY LARGE OBJECT B 1 1 B 1 Antenna coupling on an electrically large object Keywords electrically large MLFMM CFIE coupling antenna placement S parameters This example consists of a Rooivalk helicopter mock up with three monopole antennas located near the front middle and rear of the model respectively S parameters coupling are computed between the three antennas over a frequency range Figure B 1 1 3D view of the helicopter NOTE Due to calculations over a frequency range as well as the electrical size of the problem several hours of computation time is required B 1 1 Helicopter This example consists of complicated geometry and the model for this geometry is provided with the FEKO installation The important features of this model are briefly presented e The model is solved with the MLFMM this is set under Solver settings e The Combined Field Integral Equation CFIE is used This is set on the face properties All of normals of the geometry faces must point outward Requesting calculations The solution requests are e The S parameters for this model must be calculated All three ports should be included and all must be active with a reference impedance of 50 2 CEM validate After the mode
173. ut reflection coefficient for the DRA antenna May 2014 FEKO Examples Guide DIELECTRIC RESONATOR ANTENNA ON FINITE GROUND A 12 6 Waveguide port MoM SEP Modal port FEM MoM Figure A 12 3 Vertical XZ plane gain in dB at 3 6 GHz May 2014 FEKO Examples Guide A LENS ANTENNA WITH GEOMETRICAL OPTICS GO RAY LAUNCHING A 13 1 A 13 Analysing a lens antenna using the geometrical optics GO ray launching Keywords Geometrical optics lens antenna dielectric radiation pattern radiation pattern point source A 13 1 Creating the lens model A dielectric lens with a spherical surface S and elliptical surface S is constructed The lens is illuminated by a radiation pattern point source based on a precomputed cos x radiation pattern and the far field pattern is computed The lens structure is modelled using the geometrical optics ray launching GO method The results are compared to the MoM FEM result The model is shown in Figure A 13 1 Figure A 13 1 The 3D view of the dielectric GO lens model with a point excitation symmetry planes shown Creating the model The model is constructed in millimetres It is assumed that the focal point of the lens is positioned at the global origin A lens shape consisting of a spherical surface and an elliptical surface is assumed The spherical surface is centred at the focal point The dielectric lens model has the following
174. wn in figure H 3 1 This example illustrates several of the techniques available in FEKO to reduce the required resources for electrically large models Figure H 3 1 Illustration of a circular horn and parabolic dish reflector It is important to understand the problem to be solved and the approximations being made to reduce the required resources Employ the following techniques to reduce the required resources e Use the multilevel fast multipole method MLFMM instead of the method of moments MoM for electrically large models The required memory are reduced considerably by using MLFMM The MLFMM solution is used as the reference solution in the results section H 3 7 e Large element physical optics LE PO used on sub parts of the model e Subdivide the problem and use an equivalent source Possible equivalent sources are Aperture source using the equivalence principle a region can be replaced by equiv alent electric and magnetic field sources on the boundary of the region Spherical modes source the far field can also be used as an impressed source H 3 1 MoM horn and LE PO reflector The first example creates the horn and the dish Simulate the horn using the method of moments MoM and the dish reflector using large element physical optics LE PO May 2014 FEKO Examples Guide HORN FEEDING A LARGE REFLECTOR H 3 2 Creating the model The model is created in two parts create the horn first and second

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