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Acquisition System of S-Parameters for the Microwave Imaging of a

1. 1 2 O A R Mohassel Doctoral committee Professor chen to tai chairman Ph D dissertation The University of Michigan 1982 S Best and J Morrow Limitations of inductive circuit model representations of meander line antennas in Antennas and Propagation Society International Symposium 2003 IEEE vol 1 June 2003 pp 852 855 vol 1 K Deng and M Ma The study and implementation of meander line antenna for an integrated transceiver design 2010 P Frost 2015 What if anything makes shielded loop antennas so great at rejecting local noise Online Available http electronics stackexchange com questions 70262 what if anything makes shielded loop antennas so great at rejecting local nois R J Spiegel C A Booth and E L Bronaugh A radiation measuring system with potential automotive under hood application Electromagnetic Compatibility IEEE Transactions on no 2 pp 61 69 1983 R Hartley 2015 Rf microwave pc board design and layout Online Available ttp www qsl net va3iul mRS mini Radio Solutions 2015 minivna pro Online Available http miniradiosolutions R P Foundation 2015 Raspberry pi 2 model b Online Available www raspberrypi org products raspberry pi 2 model b D Krause vna J 3 1 4 User guide 2015 Online Available http download dl2sba com vnaj manuals UserGuide pdf vwna J 3 x User guide for head
2. 8 Sag EOPOROROR dum ok aon a R Po ERE SER Pe RE UE Reus 9 2 9 S11 curve for meandered antenna in HFSS o e e o 10 dota AN 11 2 11 12 curve for cross plane polarization in HFSS o o 11 2 12 12 curve for co plane polarization in HESS o e 12 2 13 12 for cross plane polarization in real test o ee eee 13 2 14 12 for co plane polarization in real test o o o e 13 AAA E ae ee da da Reo ee eS 16 Tr rcr ee ee a 17 Pee faced hoe en fe A Xo Wut Bonos 18 2 19 SII smulatedl u egece e 9b Y ie ee ORA P S ee a ee ele 19 E IS e s 19 2 20 E distribution with shielding o o e o 20 viii Microwave Imaging of a Grain Bin LIST OF FIGURES 2 21 E distribution Shielding removed o 20 TC 21 2 23 field lines in G TEM for reference 2 aa 21 DIT 22 TP Sek hae Be ee we eh ae eae eae Rae a 23 3 1 Multiplexer connecting VNA to antenna array a 25 poa ea ean P Gee ee x RSV Bb Bee ee es 26 Wty he So ace eects ach red d teres ee he be dte tae 27 3 4 PCB layout for SP3T board 2 ss 27 3 5 PCB layout for top layer of SP8T and SPDT board 28 3 6 PCB layout for bottom layer of SP8T and SPDT board 29 be fe Oe Reick eh aa Pe Be At T 29 eee Aenea 32 Be Byte au VM DUREE eae MUR PS 33 34 aia a we eS Ge SS x udo XXE Nude 39 4 2 S11 measurement real f
3. 60 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 4T 48 49 50 51 52 53 54 55 56 57 Microwave Imaging of a Grain Bin B 1 gbin sh else echo Tx 1 2 echo Rx 3 4 stty F dev ttyACMO cs8 9600 ignbrk brkint imaxbel opost onlcr isig icanon iexten echo echoe echok echoctl echoke noflsh ixon crtscts hupcl for i in seq 1 2 do if i 1t 10 then echo sending O i to arduino echo n O i gt dev ttyACMO else echo sending i to arduino echo n i gt dev ttyACMO fi echo changing transmitter to i for j in seq 3 4 do echo n j gt dev ttyACMO echo changing reciever to j echo Running vnaJ h1 3 1 3 jar nohup java Dconfigfile gbin xml Dfstart 70000000 Dfstop 100000000 Dfsteps 100 Dcalfile gbin cal Dscanmode TRAN Dexports csv jar vnaJ hl 3 1 3 jar gt log txt path vnaJ 3 1 export renaming exported file for post processing i lt 10 amp txz O i tx i rcvr expr j 24 rcvr 1t 10 amp amp rx O rcvr rx rcvr mv HOME path gbin cal csv HOME path gbin_ tx rx csv done done fi 61 58 59 60 61 62 63 64 65 O o ny one UNA NNN NY NY YD PK BB Be pap pop op Q CU MA C22 cC qQ Ooo 10 Ct A UONE Cc Microwave Imaging of a Grain Bin B 2 put2str cs running post processing process mono put2str exe delete all exporte
4. however the necessary directories will be created on the root directory of the RPi2 which includes e root vnaJ 3 1 export e root vnaJ 3 1 calibration e root vnaJ 3 1 config There are two key files that need to be present for the vnaJ hl 3 1 3 jar file to execute properly The first one is the configuration file gbin xml refer to the vnaJ software manual on how to create this file 9 The XML file includes the USB port name for the software to communicate with the MVP This file must be stored in the root vnaJ 3 1 config directory The second key file is the calibration file for transmission mode which are created using the vnaJ 3 1 3 jar GUI software that must be run on a separate computer that supports either Mac OS or Windows The user should consult the vnaJ software user manual 9 for details on how these calibration files are created using the vnaJ 3 1 3 jar GUI This calibration file is stored in the root unaJ 3 1 config directory The RPi2 is now setup to run the gbin sh shell script that runs the SPDAQ software In order to use the button and LED feature the python script button py needs to be executed The simple command Python button py will run the python script and will listen for the user to press a button to initiate the gbin sh script In order to setup the python script button py at bootup the following command can be entered on the terminal of the RPi2 49 Microwave Imaging of a
5. 80 00 a2 90 00 100 00 I i er i 50 00 75 00 125 00 Freq MHz Fig 2 12 S12 curve for co plane polarization in HFSS 12 Microwave Imaging of a Grain Bin 2 1 E field Antenna Fig 2 13 S12 for cross plane polarization in real test Fig 2 14 S12 for co plane polarization in real test Microwave Imaging of a Grain Bin 2 2 H field Antenna As a conclusion for 12 curves shown in Figures 2 13 and in HFSS the results is pretty good that difference between co plane and cross plane of 12 is about 15dB but in the real test the difference is 5db the cause for the difference in quantity is from the non ideal air box and ground plane from the lab comparing to the ideal ones in HFSS Further improvement for the testing method is still required 2 2 H field Antenna 2 2 1 Purpose Normally microwave imaging systems consist of a simple E field antenna such and a monopole or a dipole antenna which has one polarization and it is limited in its functionality however it is simple to model in the imaging inversion algorithm as these types of antennas have very simple and well defined current distributions along them Due to a grain storage bin being round metallic and closed off at both ends it can be thought of as a cylindrical resonant chamber which introduces a level of difficulty in designing antennas that can operate in such an environment However since the walls of the bin are metallic the field components
6. Dfsteps Steps Dcalfile gbin cal Dscanmode TRAN Dexports csv jar vnaJ hl 3 1 3 jar Where the following parameters are defined in Table Table 5 V Parameter definitions for miniVNA PRO software command Parameter Description Start Frequency range start Hz Stop Frequency range stop Hz Steps Number of Frequency steps The command is set within the shell script by default as java Deonfigfile gbin aml Dfstart 70000000 Dfstop 100000000 Dfsteps 100 Dealfile gbin cal Dscanmode TRAN Dexports csv jar vnaJ hl 3 1 3 jar Where the frequency range is 70 100MHz with 100 steps The user can refer to the vnaJ Headless Software Manual for additional information 51 Microwave Imaging of a Grain Bin Chapter 6 Future Work At the moment the SPDAQ system is at an early stage of development Our team has developed an Alpha prototype of the SPDAQ system for hardware and software testing in order to establish a proof of concept for this project Although our team was successful in integrating the many hardware and software components for the system there are still many things that can be improved on to make the system accessible to the general public Initial designs for the SPDAQ system was to implement a battery operated device however due to project time constraints and project delays this feature has yet to be implemented but should considered for future iterations This chapter will explain the
7. Microwave Imaging of a Grain Bin DEFINITIONS Er DC SPDT SP3T SP8T prepreg CLI SSH SFTP IP SPI GPIO GUI UI Relative Permittivity Propagation constant Frequency in radians Permeability Angle Phase in degrees Direct current Single pole dual throw Single pole three throw Single pole eight throw Pre impregnated thermoplastic resin Command line interface Secure shell protocol Secure file transfer protocol Internet protocol Serial peripheral interface General purpose input output Graphical User Interface User Interface xiii Microwave Imaging of a Grain Bin Chapter 1 Introduction 1 1 Purpose The Canadian farm industry is a multibillion dollar a year industry which needs to provide for a growing human population High production of grain requires farmers to dry and store the grains that they grow however this introduces problems such as possible spoilage of the grain as well as proper humidity control Spoilage and water has dielectric properties which are different of those that dry good grain has therefore these anomalies can be detected with the use of a microwave imaging system which consists of a Vector Network Analyzer a 2xN RF multiplexer an N array of antennas and a computer for collecting and analyzing the scattered parameters to create a three dimensional image of a material However typical microwave imaging systems are very costly and
8. ori ey op ror 91 t og og ss ow ow o w o o m cDODcGODuuu s m exe w wm wm wm wm m m Qr or or or roro or or or or tr or or or ror or dr dr ror t og or or o cr ro 1 Aaa ajajaja 0699 16114 11 1 o o 1 1 1 1 eoc c rmt rs SOFSr wr 1 1 1 1 1 1 1 popa 1 1 ra aim aaa omo 1099 14 11 1 g1gg 6gJ 9 if if if ofj or ep ep ay ey ad ey ep or or ey ey oy ey ey o3 ep if rf t ij or or or ep ory ayo ay edad or or or or or or gr og og paja RR wm wi wi wi wr m m Ss sos 16g PEEL EEE EEEEEEEEEELELEL Fig D 1 Microwave Imaging of a Grain Bin Appendix E Curriculum Vitae Dimitri Anistratov PLACE OF BIRTH Winnipeg Manitoba YEAR OF BIRTH 1991 SECONDARY EDUCATION University of Manitoba 2009 2015 Robert Brandt PLACE OF BIRTH YEAR OF BIRTH SECONDARY EDUCATION HONOUR AND AWARDS Winnipeg Manitoba 1979 University of Manitoba 2010 2015 Dean s Honor Roll 2010 70 Microwave Imaging of a Grain Bin Shucheng Gu PLACE OF BIRTH YEAR OF BIRTH SECONDARY EDUCATION HONOUR AND AWARDS Nanjing China 1990 University of Manitoba 2010 2015 Dean s Honor Roll 2010 Kathy Nguyen PLACE OF BIRTH Winnipeg Manitoba YEAR OF BIRTH 1989 SECONDARY EDUCATION University of Manitoba 2010 2015 71 Microwave Imaging of a Grain Bin PLACE OF BIRTH YEAR OF BIRTH SECONDARY EDUCATION HONOUR AND AWARDS
9. A VNA was required for sending and receiving signals to and from the antennas and a multiplexer was required in order to connect the VNA to the array of antennas and perform the necessary switching Also a microprocessor and software was needed to provide control to the multiplexer and perform data acquisition and management It was found that the E field antennas designed were not suitable for real world use for this application however the H field antennas performed well Due to time constraints and issues with our original supplier for our PCBs we were unable to complete the multiplexer in time for this report however we hope to have something in time for our presentation For testing our system we used an existing switch provided by EIL The miniVNA PRO was a very affordable option but we were unable to get direct access to data obtained through it which resulted in our system being very slow in running through its data acquisition procedure If direct access to this data were possible or a different VNA was used which allowed this direct access our system would perform much quicker 54 Microwave Imaging of a Grain Bin With a bit more work to complete with the multiplexer and resolving the issue with the limitation of the MVP s manufacturer software we feel that we can succeed at creating an affordable and portable system for detecting moisture inside a grain bin 55 Microwave Imaging of a Grain Bin REFERENCES References
10. Bin 2 1 E field Antenna The limitation of inductor circuit model of the meandered antenna is still in examining we simulated that some of the physical properties varied and the corresponding change of the resonant frequency Firstly we change the s in M1 configuration from 1cm to 2cm the resonant frequency behavior of the antenna versus the meandered sections is shown in Figure 2 4 We can observe that the actual resonant frequency will not precisely change as we seen in Figure HFSS simulation results 250 200 150 100 50 Resonant frequency MHZ 1 1 2 1 4 1 6 1 8 2 meandered spcing cm Fig 2 4 resonant frequency vs meandered spacing Next we examined the effect of bending angle changing for each meandered section shown in Figure 2 5 2 Fig 2 5 Bending angle when a 45 60 75 90 120 degree conditions Microwave Imaging of a Grain Bin 2 1 E field Antenna We bend the antenna for the configuration M5 too see the simulation results in HFSS while keep the total physical length and spacing as the same as the previous model The relation between bending angle and self resonant frequency is shown in Figure 2 6 1 HFSS simulation results 140 120 100 80 60 40 Resonant frequency MHZ 45 60 75 90 105 120 Bending angle a degree Fig 2 6 the relation between bending angle and resonant frequency Br e gt Fig 2 7 radiation principle of a 90 degree bending meandered antenna
11. Edinam Tettevi Accra Ghana 1989 University of Manitoba 2010 2016 MTS Mobility Scholarships 2011 International Undergraduate Student Scholarship Dept of Development amp Advancement Services Scholarship University 1 Honor List Fall 2010 University 1 Honor List Winter 2011 Dean s Honor List Fall 2013 72
12. Microwave Imaging of a Grain Bin 2 1 E field Antenna It is observed that resonant frequency would experience a little fluctuate when the bending angle is changing from 45 to 120 degrees Nevertheless we need to obtain a relatively large difference between cross plane and co plane polarization as we can see in Figure the 90 degree bending angle will provide a cancellation of radiation in horizontal axis due to the opposite flowing direction of two current At the same time the radiation current will always along a same direction in vertical axis as a result the radiation of the 90 degree bending antenna is equivalent to a single line monopole antenna Furthermore the 90 degrees bending method will save room on PCB board so that the total physical length of the antenna will get dropped 1 2 1 2 Antenna Building and Testing After investigating the effects of numbers of section section spacing and bending angle we start to build a meandered antenna on the substrate to satisfy the specification of the antenna parameters As seen in Figure 2 8 the spacing between each meandered section is 0 5cm the number of mean dered sections is 14 in total and the S11 graph is shown in Figure 2 9 which provide us a return loss below 10dB at 80MHz Fig 2 8 final antenna view Microwave Imaging of a Grain Bin 2 1 E field Antenna The physical length of this antenna is 80cm in total with the height of 10cm on the substrate a top loading c
13. and simulations we run serves to hold that our diodes will work well within our range of interest 36 Microwave Imaging of a Grain Bin Chapter 4 Vector Network Analyzer The vector network analyzer is a key component of the S Parameter Data Acquisition SPDAQ system since it is the actual instrument that measures the S Parameters of the grain storage unit 4 1 Harware Specifications In order to implement a practical system that would be ideally used by agriculturalists such as farmers the VNA had to be portable yet affordable Lab quality VNAs are very expensive usually costing tens of thousands of dollars and therefore cannot be used for the SPDAQ system Due to the fairly low frequencies being transmitted and received from the antennas within the grain storage unit the VNA can be more affordable than those usually found in a lab On top of these main specifications of a compact low costing VNA the analyzer had to be a two port system so it is capable of S11 and 12 measurements for the microwave imaging of the grain bin as well as being capable of measuring within the frequency range of a typical grain bin and can offer a good dynamic range Table shows the exact specifications required for the SPDAQ system to be effective 37 Microwave Imaging of a Grain Bin 4 1 Harware Specifications Table 4 1 VNA Requirements Frequency Range 70 MHz 100 MHz Dynamic Range 10 dB System Type 2 port with S11 and S12 Bud
14. commands sent from the DC switch the multiplexer is capable of connecting either of these two ports to any of the antennas in the array 3 1 RF Switch 3 1 1 Background The multiplexer must connect the ports from the VNA in a certain sequence First the multiplexer will be configured to connect the transmitter port from the VNA to antenna 1 After this antenna 2 will be connected to the receiver port of the VNA Then antenna 3 connects to the receiver port then antenna 4 and so on through the entire array of antennas Once this sequence has been 24 Microwave Imaging of a Grain Bin 3 1 RF Switch completed the multiplexer will now be configured to connect the transmitter port of the VNA to antenna 2 after which antenna 1 will be connected to the receiver port then antenna 3 then antenna 4 and so on through the entire array again The multiplexer will repeat this sequence until all antennas have acted as the transmitter with the remaining antennas acting as receivers transmit Vector Analyser receive Antenna Multiplexer Array Fig 3 1 Multiplexer connecting VNA to antenna array 3 1 2 Design An initial design for the RF multiplexer was created using six 4 x 2 matrix switches together two SP3Ts The topology of this design is shown in Figure Note that not all of the 4 x 2 matrix switches are shown in the Figure 4 more of these switches are connected to the two remaining pins of the two SP3Ts for a tota
15. has to be affordable yet accessible so that it can be used by the targeted consumer who are grain farmers The antennas used in the bin would have to be miniaturized and easily manufacture able At least 16 antennas with the possibility of 2 types will need to be produced The RF switch that links the antennas to the VNA needs to have some sort of discharge protection a minimum of 24 switching ports with relatively low noise and insertion loss The processes need to be automated with the push of a button which offers an ease of use for the user Microwave Imaging of a Grain Bin Chapter 2 Antennas 2 1 E field Antenna The data acquisition system of a grain bin is based on the use of microwave imaging system to estimate the dielectric properties of the material in the grain bin As explained in the section of introduction The object of the antenna is to receive or transmit scattering parameter data to local PC for analyzing propose Table 2 1 specification of the E filed antenna Specifications Value Resonant frequency 70MHz 90MHz 1 at operating frequency Below 6dB Antenna size Maximum 10 x 15 cm Co plane and cross plane polarization difference At least 15dB Number of antennas in an array 24 In the previous MWI system the straight line monopole antenna with a total length of 1m is used inside the bin however in the resonant chamber each antenna size cannot exceed a 10 15 cm due to the
16. possible work that can be done to advance the current alpha prototype of the SPDAQ system and its individual components 6 1 Software As of now the current software is at its very basic form where a shell script executes the SPDAQ software on the RPi2 with very little interface for the user to interact with The user can edit certain files on the RPi2 in order to modify the settings which requires root access to the RPi2 This current method requires a good knowledge of the LINUX OS which is not commonly known by the average user By implementing a more advanced GUI the user can have more control over 52 Microwave Imaging of a Grain Bin 6 2 RF Multiplexer Module the SPDAQ system with an easier method to setup and configure any of the settings of the SPDAQ software The GUI can also offer an easier method for the user to connect the RPi2 to the Internet for cloud services with a use of a Wifi adapter To improve the software runtime the use of another VNA that is open source should be considered in newer iterations of the SPDAQ system 6 2 RF Multiplexer Module At this stage the RF Multiplexer component is currently being built and has yet to be tested Through our SPDAQ prototype testing we used an old RF Switch module provided by the EIL for the Alpha build The RF Mux module designed by our team offers the same logistics as the RF Switch module provided by the EIL and therefore the upgrade to the newly designed RF Mux model o
17. proportional to the number of turns squared R INS however it is also not feasible for the grain bin since it would not guarantee that the antenna does not pick up the E field as well and it would be too complex to model in the imaging software 2 2 3 Design In order to satisfy the main requirement of the antenna 1 a shielded and slotted loop antenna was chosen which is a common type of antenna used in radio The ground layer around the conductor which acts as the shielding modifies the electric field distribution inside of the antennas cross sectional area due to the boundary conditions on a PEC thus reducing its effect on the antenna this effect is confirmed in the simulation results in section Since the magnetic field passing through the loop induces a current on both the conductor and the shielding a slot is cut out in the shield to create a capacitance which introduces a phase shift between the two currents and therefore there is a difference in potential across the load 5 The second requirement 2 was met by reducing the perimeter of the antenna to A 20 how 15 Microwave Imaging of a Grain Bin 2 2 H field Antenna Fig 2 15 shielded loop antenna ever the small size presented another challenge which is matching the loop antenna to the 50ohm coaxial line different ways of matching were considered such as capacitive coupling and transformer coupling between the coaxial line and the antenna These were simulated i
18. therefore 0 2mm was chosen as the gap between the conductor and the ground planes of the co planar waveguide With the help of TX line transmission line calculation software a conductor size of 2 57mm with a gap of 0 2mm and a 0 8mm FR 4 thickness yields the necessary 50ohm transmission line The size of the antenna is 12 5cm in length and 5 5cm in width with 45 degree bends for reducing reflections the bent sections are 1cm long 2 2 5 PCB Antenna Simulation The PCB version of the antenna is constructed in the high frequency structure simulator with FR 4 as the substrate material copper material on top of the substrate is simulated as perfect conductor and an infinite ground plane as the antennas backing plate The design is simulated and optimized to obtain its performance characteristics From optimization a slot size of 1 mm is chosen in the 17 Microwave Imaging of a Grain Bin 2 2 H field Antenna shielding ba mens Fig 2 17 HFSS model of PCB antenna 2 2 6 Simulation Results The desired result is to have an S11 insertion loss of 10db at the frequency of operation and as expected the insertion loss at 80 MHz is 14 5db as well as due to the 50 ohm termination the antenna has a really high bandwidth The simulation also confirms the effect of the co planar ground plane on the Electric fields inside the cross sectional area of the antenna Figure 6 and Figure 7 show the antenna with shielding and ante
19. volume limitation of the inner space After investigating several options focusing on classes of small patch antennas a suitable and feasible method has come up as meandered monopole Microwave Imaging of a Grain Bin 2 1 E field Antenna antenna printed on a PCB layer The FR4 with e 4 4 will be used as the dielectric substrate of the PCB board 2 1 1 Research and Preliminary Design We will start the design process from the researching and simulating the features of the simple straight line monopole antenna then we need to determine the parameters of the meandered an tenna in order to increase numbers of meandered sections to satisfy the size requirement The following parameters we need to consider e Numbers of meander sections e Spacing of meander sections e Bending angles for each section A simple single straight line monopole antenna can be represented using an equivalent inductor circuit model in Figure 2 1 If an additional equivalent component is added up to the self inductance of the antenna the resonant frequency of the meander line will be relatively change compared with previous antenna with same height this method will provide us a reasonable approximation of the working principle of this class of antenna Next we need to demonstrate several simulations and optimizations to figure out how the meander line configurations will change the performance of the antenna return loss curve S11 radiation patterns in term
20. was based on using a 4x2 matrix switch was not going to be feasible with the original schematic and a more complex design is shown in Figure had to be implemented It is definitely more rigorous that the first but had however proved to be better It this sense the DC switch supports a multilayer RF switch design and can feasible 32 Microwave Imaging of a Grain Bin 3 2 DC Switching STOTT 5 Taber Sri Di ay File Cl sit UC SE SDE Dua Fig 3 9 Initial DC Switch Design for Matrix Switch Design be cascaded with a similar DC switch design should the side of the antennas double or quadruple with the addition of an external enable switch Software The software control of the DC switching circuit is done by an Arduino microcontroller loaded with a table that references the control lines for each multiplexer This allows the SPDTs to function as an input or an output depending on the values set on the control lines but the Arduino And will be concurrent with the presents action of the VNA such that only one SPDT is in transmit mode at a given time The software will also turn on one the SP8T for transmission of the signal 33 Microwave Imaging of a Grain Bin 3 2 DC Switching Fig 3 10 Final DC Switch Design for Multi Layer RF Switch Design and turn the other SP8Ts responsible for reception of the signals A
21. 000 000 119 999 999 calibration steps 2000 420 000 000 200 000 000 Ge iex ee NNNM Fig 4 1 miniVNA PRO calibration software The S11 measurement of the miniVNA PRO was then compared to the S11 measurement of the EIL VNA in order to verify the calibration was performed correctly on the miniVNA PRO The RF Switch module provided by the EIL was used as a load The S11 output of the RF Switch transfer function is shown in Figure 4 2 and 4 3 for both the EIL VNA and the miniVNA PRO Both the real and imaginary part of the S11 measurement are fairly similar with a slight discrepancy in the real part of S11 in the miniVNA PRO which may be due to the calibration kit used with the miniVNA Pro since the kit was designed for the EIL VNAs With fairly accurate results the MVP 39 Microwave Imaging of a Grain Bin 4 2 Calibration and Testing gave us confidence in using it for the SPDAQ system miniVNA PRO real EIL VNA real S o a2 re rt o 0 02 04 06 08 1 12 14 16 18 2 108 Freq Hz i Fig 4 2 S11 measurement real for both VNAS miniVNA PRO imag EIL VNA imag E S 5b S 8 a re re o 16 18 2 108 0 02 04 06 08 1 12 14 Freq Hz Fig 4 3 miniVNA PRO open port measurement in reflection mode 40 Microwave Imaging of a Grain Bin 4 3 miniVNA PRO Software 4 3 miniVNA PRO Software The MVP was designed to be software defined and t
22. 15 Microwave Imaging of a Grain Bin LA E eR a ee o E Bae 17 2 2 5 PCB Antenna Simulation 2 0 0 0 00020 ee ee ee ee 17 2 2 0 Simulation Results 2 2 ee 18 2 2 PCB Layout 24044 2245405844 2 Row ccc RYE x ae ek Pa UR 20 2 2 8 H field Antenna Testing 2 2 0 0 0 0 e 21 2 2 9 G TEM Test Results 2 0 0 0 ss 22 DE Geek Bo A BE eee ew Be ae a ae eG Gla a 24 3 1 RE Switchhs ax 2i0 bee he ended end de eae Rex Pete de ea wea e a 24 3 1 1 Background 4o bor Rod RE s o RR WO ee we ee we a 24 che dnd WEE Ros amp De Hae eee Rom Fee x ee A RUE Kod WX E ds 25 3 2 DC Switching e 2 Eos auk klk Gad aie ALS XD ure o GORGE Ge Eau ed Rd 31 3 2 1 Hardware 2 oi xem p Eo Rex hE we EE EE RUE 31 ib Sid MaDe eee tee eis d Rom EUR E AR eee doc HS 36 CIPIT 37 Go SW Gee aE wad Ge Rk deu dod GO Sond ae d S Pe ae ed 37 4 2 Calibration and Testing aa a ee 39 4 3 miniVNA PRO Software 2 lll ss 41 A a on ia ed 42 le po o A Gi A he ange ee dt 42 E Gd eG ae ao ES dre ees 43 5 2 1 Initialization Process 4 222 es 44 rr 44 5 2 3 Post Data Processing ce e a csi a aa woa a a e 45 5 2 4 Data Transmission Process ee 4T TEE 47 vi Microwave Imaging of a Grain Bin TABLE OF CONTENTS 5 3 1 Prerequisites o e s b a4 4 lt a ee Be RR ee Gn eR RUE OUS 48 5 3 2 Configuration Parameters 2 e a e a a 50 6 Future Work 20 sos siss s osoa d
23. 2 Signal Copper 0 036 Not Allowed II Dielectric 3 Dielectric Core 0 6 FRA 42 EH ES EN B EE BW HE Botomiayer Signal Copper 0 03556 Bottom Bottom Solder Solder Mask Co Surface Material 0 01016 Solder Resist 3 5 Bottom Overlay lovertay Fig 3 7 Stack up for PCBs in Altium 29 Microwave Imaging of a Grain Bin 3 1 RF Switch Both boards used co planar waveguides with ground for all of the RF traces and were designed such that they were 50 ohms This resulted in a trace width of 0 5 mm and a gap of 0 115 mm with a substrate thickness of 0 6 mm Three 10 pin connectors were added to provide power as well as connect all of the control pins for the SP8T and SPDT switches 6 Unfortunately due to issues with our original intended supplier of our PCBs we were unable to get these PCBs printed in time for this report We found another supplier for our PCBs and hope to have them before our presentation The PCBs needed to be modified somewhat due to different PCB specifications from this new supplier Minimum routing size was larger at 0 1524 mm compared to 0 1 mm with the original supplier Also the substrate thickness options were different not allowing us to use a thickness of 0 6 mm Based on the specifications of the new supplier the RF traces needed to be modified to 0 185 mm thick with a gap of 0 1524 mm This is based on a substrate thickness of 0 1 mm 30 Microwave Imaging of a Grain Bin 3 2 DC Swit
24. A 3 26 24 EIL 7824 sooo Provided by EIL HMC245QS1 Provided by EIL SP3T Digikey A O51 4 13 2 EIL 826 0 00 LONGE By SP8T Digikey ees 10 28 6 EIL 61 68 sooo Provided by EIL Arduino Newark 45W6205 40 21 1 EIL 40 21 0 00 Provided by EIL 10 board 5 Process of RF Multiplexer PCBs SeeedStudio EIL 80 00 0 00 R 6 board 5 5 5 ordering Raspb Pi B Ord laced mM Newark 68X0156 43 60 1 ECE 43 60 43 60 TOR pa 8GB microSD card and received Controller Order placed Raspberry Pi 2 Newark 38Y6467 39 99 1 ECE 39 99 39 99 dad recelucit Electrical components MISC wiring resistors ECE 100 00 capacitors etc Machine Time U of M 8hrs 0 00 ECE EIL Project Total Subtotal 83 59 1446 94 1530 53 396taxes 10 87 188 10 198 97 Shipping 8 160 11 168 11 Total 102 46 1795 15 1897 61 59 Ae w N A O ON a Cc 11 12 13 14 15 16 17 18 19 20 21 Microwave Imaging of a Grain Bin Appendix B S Parameter Data Acquisition System Software B 1 gbin sh Code B 1 S Parameter Data Acquisition Shell Script Software bin bash if f vnaJ h1 3 1 3 jar then echo ERROR Missing vnaJ file exit fi if z lsusb grep e Future Technology Devices then echo ERROR MiniVNA Pro not connected fi if lt 4 1 then echo ERROR Missing parameters exit T3 if z lsusb grep e Arduino then echo ERROR Arduino not connected
25. Data Processing is complete in which it executes a command in Linux that triggers an upload of the specific file to Dropbox Dropbox is a widely used cloud storage service that anyone can register for free for basic cloud storage space This service can be accessed online remotely from the users own PC through the many interfaces that Dropbox offers ex website computer software etc which makes it very convenient for the user to retrieve the data from the SPDAQ device and therefore was selected for our system Appendix B 4 instructs how a user can unlink or link a specific Dropbox account onto the RPi2 as well as additional commands 46 Microwave Imaging of a Grain Bin 5 2 Software Design and Integration Read line to get Open file transmission loss and phase data Calculate S12 real and Retrieve Tx and Rx 4 Did the MVP from file name and imaginary component N laco export any CSV files store in data array sp and store in data array sp Data Transmission Process Any files left to process Write Tx Rx and 12 data string to sp dat file in output folder Fig 5 4 Flow Chart of Post Data Processing Procedure However if the SPDAQ system is unable to connect to the Internet to upload the data file the user can still manually retrieve the data through the following methods 1 Ejecting the micro SD card located underneath the RPi2 in which the file is stored on 2 SFTP wi
26. E m nn ok See eh ee eb RUE Xo d a d d 52 o ivo X a we ek Pele ee OUR ee ee RE Ege 52 6 2 RF Multiplexer Module 2 rss 53 0 9 Amntennna ess a a RO Goad xt dee bebe Se ee Rex JA Ee Ub Sw Swe HOE 53 T Qonclusions s s a 2 54 3 xk ee x O4 d Boh EIE X 4o AOR aS a RR s 54 s Beatie guar dodi op d beg RUE xk oup WR EUR a ee EURO inie OE RE 56 Appendix A Appendix Al ss sss 58 Appendix B AppendixBl a 60 Bl gbmish se noe nee a ee ewe te be REA EVA Ee qum eee ee d ues 60 H2 PULS CSa coa V emo wc hk Be vong xe uice uL Ree eh et e ee eae 62 B 3 button py e a 2 4 ad ow 3k oro X kOROESRoR WO Goch Seu qox Rd Pw x NR een 64 B 4 Dropbox Setup on the Raspberry Pi 2 22s 65 B 4 1 Setup Instructions 65 B 4 2 dropbox uploader sh Commands 0 0 02 0002 65 Appendix C Appendix QU 67 Appendix D Appendix D 2l ss 68 Appendix E Curriculum Vitae 2s 70 vii Microwave Imaging of a Grain Bin LIST OF FIGURES List of Figures 2 1 equivalent model of meander line sections e 5 2 2 meandered monopole antenna geometry a e 6 2 3 Resonant frequency of meandered line antenna MO to M5 6 2 4 resonant frequency vs meandered spacing 2 2 0 ee ee 7 e os 7 2 6 the relation between bending angle and resonant frequency 8 2 7 radiation principle of a 90 degree bending meandered antenna
27. Grain Bin 5 3 Software Setup and Configuration crontab e A file will come up and in this file enter in the line at the very bottom reboot python root grainbin button py Save the file and now the RPi2 will run the python script at bootup enabling the button and LED function To connect the LED and push button to the RPi2 review Figure and Appendix C for GPIO pinout on the RPi2 5 3 2 Configuration Parameters gbin sh Parameters The gbin sh shell script file is designed to take four parameters that define the number of trans mitters and receivers being used with the SPDAQ system The command to run the gbin sh file through the RPi2 terminal is sh gbin sh 1 2 3 4 The four parameters are defined in Table Table 5 IV Parameter definitions for gbin sh Parameter Description 1 transmitter antenna start number 2 transmitter antenna stop number 3 receiver antenna start number 4 receiver antenna stop number An example of this command when using transmitter antennas 1 10 and antennas 11 20 as receiving sh gbin sh 01 10 11 20 50 Microwave Imaging of a Grain Bin 5 3 Software Setup and Configuration miniVNA PRO Software Parameters The MVP software is executed within the gbin sh shell script refer to Appendix and the parameters can be changed by changing the following command within that script java Dconfigfile gbin xml Dfstart Start Dfstop Stop
28. N4_miniVNA pro cal mini radio solutions miniVNA pro cu usbserial A1011K0S 100 000Hz 200 000 000Hz 1 400 points 70 000 000Hz 100 000 000Hz Users knguyen vnaJ 3 1 export VNA s2p ob finished successfully kathy nguyens macbook pro grainbin knguyen Fig 4 4 miniVNA PRO Software Output The MVPs software used for the SPDAQ system is the vnaJ hl 3 1 3 jar file 9 that runs on a headless system no graphical user interface When the jar file is executed with the specified parameters frequency start stop and steps the MVP takes the readings and exports them to a CSV file the file type is specified within the parameters of the jar file An example output of the MVPs software running through a command line interface CLI is shown in Figure 41 Microwave Imaging of a Grain Bin Chapter 5 Microprocessor 5 1 Hardware Integration Due to the software limitation of the MiniVNA Pro MVP a microprocessor was required to run the MVPs software This is where the Raspberry Pi 2 RPi2 was chosen The RPi2 microprocessor will be used to control both the RF Multiplexer and MiniVNA Pro MVP of the S Parameter Data Acquisition SPDAQ system The specifications of the RPi2 are shown in Table 5 1 Table 5 1 Raspberry Pi 2 Specifications Processor 900Mhz quad core ARM Cortex A7 CPU RAM 1GB USB Ports 4 GPIO Pins 40 The RPi2 offers enough USB ports to c
29. Since the SPDAQ system has no need for a GUI and the software that will be running on the RPi2 did not require much to run the Arch Linux OS provided a great solution for our system 43 Microwave Imaging of a Grain Bin 5 2 Software Design and Integration For the SPDAQ system there are four main processes that the system is required to run Initialization Data Acquisition Post Data Processing and Remote Data Accessing The order of all these processes and procedures that run on the microprocessor are shown in Figure 5 2 Initialization Data Acquisition Post Data Data Transmission Process Process Processing Process Fig 5 2 S Parameter Data Acquisition system processes 5 2 1 Initialization Process The initialization process requires the user to interact with the system to power on and start the other processes that are executed by a shell script The procedure is as follows 1 Power on the S Parameter Data Acquisition SPDAQ system by connecting the RPi2 to a power source 2 Once booted up allow approximately 7s the user can now press the push button to execute a shell script that will start the data acquisition process 5 2 2 Data Acquisition Process In this process the RPi2 will control both the RF Multiplexer to switch the antennas between transmitter and receiver as well triggering the MVP to execute a sweep to obtain S Parameters of the Grain Bin The Data Acquisition Process runs through an N numb
30. University of Manitoba Department of Electrical amp Computer Engineering ECE 4600 Group Design Project Final Project Report Acquisition System of S Parameters for the Microwave Imaging of a Grain Bin by Group 07 Dimitri Anistratov Robert Brandt Shucheng Gu Kathy Nguyen Edinam Tettevi Academic Supervisor Joe Lovetri Co Supervisor Mohammad Asefi Industry Supervisors Ian Jeffrey Academic Supervisor Paul Card 151 Research Inc Colin Gilmore 151 Research Inc Date of Submission March 4 2015 Copyright C 2015 Dimitri Anistratov Robert Brandt Shucheng Gu Kathy Nguyen Edinam Tettevi Microwave Imaging of a Grain Bin Abstract This report describes the design and implementation of a s parameter data acquisition system for the use in a commercial grain storage bin The system is divided into the following components which will be described in detail in this report An RF multiplexer a VNA a microcomputer and an array of magnetic and electric field antennas The s parameter data that is collected by the system will be used by the Electromagnetic Imaging lab at the University of Manitoba to create an image of the dielectric contents of the grain bin This microwave imaging technique will be used to detect moisture and grain spoilage inside the grain storage unit which in turn offers farmers a way to protect their stock in order to maximize profits Microwave Imaging of a Grain Bin CONTRIBUTIONS Contrib
31. ap is added at the far end of the antenna to increase the S11 performance To match up the resonant circuit we add a 400nH inductor at the feeding point of the antenna When testing the S12 parameter we used a A 4 dipole antenna as port 2 in HFSS so that the designed antenna is acting as a receiving antenna in the air box The simulation model is shown in Figure 2 9 And the simulation results are listed in Figures 2 10 and AT r IOU J 2 00 4 dB S 1 14 00 r r r i r r r r 7 T 50 00 75 00 100 00 125 00 Freq MHz Fig 2 9 S11 curve for meandered antenna in HFSS In the real testing the resonant frequency got shifted to 95MHz due to the inaccurate selection of the inductor value since we can only get 330nH or 470nH one from the lab the result frequency will not located in 80MHz 10 Microwave Imaging of a Grain Bin 2 1 E field Antenna Fig 2 10 S11 curve for real testing results Name X Y XY Plot 8 Patch_Antenna_ADKv1 A m3 001608 346143 OnnE 71 dB 502 Setup Sweep 8750 50 00 75 00 100 00 125 00 150 00 Freq MHz E Fig 2 11 S12 curve for cross plane polarization in HFSS 11 Microwave Imaging of a Grain Bin 2 1 E field Antenna Name X Y XY Plot 8 Patch Anten m2 80 1508 81 2322 l 50 00 50 00 3 4 700 I 4 8
32. at the metallic walls are easily differentiable the H fields are tangential to the metallic walls of the chamber and the E fields are perpendicular to the walls thus we would like to have an antenna that is capable of probing the tangential H fields only The H field antenna design had to be confined to the following design criteria in order for it to be effective inside of the grain bin j Ability to pick up H field only and reject most of the E field 2 Minimal size less that 15cm in length or witdth 3 Frequency of operation between 70Mhz 90Mhz 4 Matched to 50 ohm coaxial transmission line 14 Microwave Imaging of a Grain Bin 2 2 H field Antenna 5 Physically able to withstand grain being filled into the bin 6 Reduced complexity for ease of modeling in the inversion algorithm 7 Ease of manufacturing and reproduction 2 2 2 Research The typical design procedure for an H field antenna is a loop of perimeter one A as at that length the loop becomes purely resistive with the maximum amount of radiation resistance however this approach does not work for the grain bin as the perimeter of the loop would have to be almost 4 meters The other typical approach to designing h field antennas is to decrease the perimeter of the loop and increase the number of turns which allows for the required size reduction that we are looking for as well as enable it to be matched to a 50ohm coaxial line since the radiation resistance is
33. ching 3 2 DC Switching A DC switch used in combination with and RF switches reduces the total labor and cost of having a separate pathways for each antenna This therefore enhances the portability of the design and reduces the complexity of very expensive PCBs due to the cheaper cost in comparison to their RF counterparts and the reduction in frequency interference due to the maximum attenuation of any frequency components at DC For our design we need a DC circuit for address decoding of the RF switch In effect the function of the DC switch is to set the control parameters in order to specify what the response of the RF switch will be at that point in time At the onset of the project we examined the previous switch design to understand how it would integrate with the RF switch and set the control parameters for the acquisition of data by the VNA Our goal was to improve upon this design so that it was feasible with the new system we wanted to implement The design of the switch required the use of Altium and the Arduino user interface The hardware was designed in Altium and the software was writing in the Arduino mainframe in the C programming language 3 2 1 Hardware The initial design appeared very complex and cumbersome to deduce because it had wires every where The first task was therefore to ascertain the possibility of having a neater hardware with very minimal adjustment to the circuit after the printing of the PCB This mean
34. complex which does not provide a feasible solution for farmers costing in the magnitude of hundreds of thousands of dollars 1 2 Design overview Our project is aimed at researching into and developing a better topology for the acquisition of s parameter data from a grain bin These parameters of the bin s contents can then be analyzed Microwave Imaging of a Grain Bin 1 3 Design specifications to produce an image that displays the grains dielectric permittivity properties to detect water contamination To accomplish our goal the project was broken into a research phase a design and integration phase and finally a calibration and field testing phase These phases would be responsible for a well rectified integration between 16 E field and H field antennas a DC RF multiplexer switch box a microcomputer a microcontroller and a portable vector network analyzer VNA The array of 16 antennas consisting of both E field and H field antennas will be built and installed in a full size grain bin A 2 port VNA via the use of a microcomputer will transmit a signal though a microcontroller which controls the RF multiplexer switch box to a single antenna and then receive the scattered signal back through each one of the other antennas The microcomputer will then collect and format the received data such that it can be processed later to create an image of the grain bin s contents on an external PC 1 3 Design specifications The system
35. d miniVNA files after post processing is done rm R HOME path upload to linked dropbox dropbox uploader sh root grainbin output output B 2 put2str cs Code B 2 Post Data Processing Program using System Ling using System IO0 using System Collections using System Collections Generic using System using System Text class put2string static string sp new string 256 3 public static void Main string args string path root vnaJ 3 1 export if Directory Exists path ProcessDirectory path else Console WriteLine 0 is not a valid directory path List lt string gt linesToWrite new List lt string gt for int rowIndex 0 rowIndex lt 256 rowIndex StringBuilder line new StringBuilder 62 27 28 29 30 31 32 33 34 35 36 37 38 39 40 Al 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 Microwave Imaging of a Grain Bin B 2 put2str cs for int colIndex 0 colIndex lt 3 collndex line Append sp rowIndex colIndex Append t linesToWrite Add line ToString export file to sp dat System I0 File WriteAllLines 0 root grainbin output sp dat linesToWrite ToArray Process all files in the directory passed in public static void ProcessDirectory string targetDirectory Process the list of files found in the directory string fileEntries Directory GetFiles
36. eep from sys import exit import os to use Raspberry Pi board pin numbers GPIO setmode GPIO BCM set up the GPIO channels one input and one output GPIO setup 17 GPIO IN push button GPIO setup 23 GPIO OUT 1led input from input_value pin 11 GPIO input 17 try while True output to pin 12 64 19 20 21 22 23 24 25 26 27 28 29 Microwave Imaging of a Grain Bin B 4 Dropbox Setup on the Raspberry Pi 2 finally GPIO cleanup if GPIO input 17 True print ON GPIO output 23 True sleep 0 5 GPIO output 23 False sleep 0 5 os system sh gbintest sh 18 18 45 50 else print OFF B 4 Dropbox Setup on the Raspberry Pi 2 The instructions below shows how a user can setup Dropbox on the Raspberry Pi 2 and how it can be linked to their Dropbox account Note that an Internet connection is required for this installation For more information on the Dropbox Uploader shell script please refer to Andrea Fabriz s Github 11 B 4 1 Setup Instructions 1 The Dropbox shell script can be downloaded using the following command wget https raw github com andreafabrizi Dropbox Uploader master dropbox_uploader sh Permissions on the shell script will need to be changed to make it executable This can be done by the following command chmod x dropbox_uploader sh Now Dropbox can be configured for the first time by running dropbox_
37. er antenna array collecting the S parameter data from the grain bin through the use of the MVP which exports a CSV file per sweep Each antenna will act as a transmitter and will loop through all n number of antennas acting as a receiver which results in an N x N number of measurements This will also result in N x N number of exported data files from the MVP due to its software limitations These data files are 44 Microwave Imaging of a Grain Bin 5 2 Software Design and Integration exported to root vnaJ 3 1 3 export directory of the RPi2 A flow chart of the Data Acquisition Process is shown in Figure 5 3 which outlines this procedure Change Tx Change Rx Execute MiniVNA Pro Software Read Data Loop through N antennas for Tx Loop through N antennas for Rx Format Exported Data Files Fig 5 3 Flow chart of the Data Acquisition Process 5 2 3 Post Data Processing Post Data Processing procedure is executed by the shell script after the Data Acquisition Process is done In this process the exported CSV files from the MVP are reformatted to a single data file which the user can access for further processing such as microwave imaging analysis of the grain bin The exported CSV files are located in the root vnaJ 3 1 export directory with the filename format of gbin_ tx rx csv where tx and rx are the 2 digit transmitter and receiver antenna number respectively
38. fter the research and understanding of requirements were satisfied a truth table was drawn in order to simplify the circuit to its least possible scenario where the fewest components are used to achieve the expected results This truth table was then transcribed into code for and then loaded unto the Arduino This Arduino was set to function in synchronism with the Raspberry Pi The pins to be used for the DC circuit had to be chosen in such a way that they match the truth table shown in Appendix D The Arduino code was then written to first store the truth table in memory and query the table with instructions when needed The row will be traversed and parameters set according to the value stores in that position of the array referencing an Arduino pin 34 Microwave Imaging of a Grain Bin 3 2 DC Switching This was an improvement on existing software which use a number of arrays to store the information and therefore introduced some time delay when looping through these arrays The software was loaded unto the Arduino and tested with LED lights to show its effectiveness in selecting the right layer and facilitation the transmission and reception of signals Our initial design required such a table for address decoding of the switch however dues to design change the code was modified to attempt to address decode single pole ICs The intention was to leave it as a table for future improvements however with time it was realized that it made the c
39. get 1000 These criteria help facilitate in the decision of selecting the MiniVNA Pro MVP by Mini Radio Solutions which offers a more affordable and portable solution for the VNA component of the SPDAQ system Table 4 11 miniVNA PRO Specifications Frequency Range 0 1 MHz 200 MHz 90 dB in Transmission mode 50 dB in Reflection mode System Type 2 port with 11 and S12 Cost 549 95 taxes and fees Dynamic Range As shown in Table 4 II the MVP meets all the main VNA requirements for the SPDAQ system which made it a valid solution for the VNA component 38 Microwave Imaging of a Grain Bin 4 2 Calibration and Testing 4 2 Calibration and Testing To ensure that the MVP meets our system s standards results measured from the MVP were compared to the more high tech VNAs in the Electromagnetic Imaging Lab EIL that are normally used for the imaging data The MVP is first calibrated using the calibration tool provided by the EIL and calibration files are created using the MVP software which is shown in Figure 4 1 amii Lam read SHORT read LOAD Connect the 0 Ohm load to the Connect the 50 Ohm standard to Leave DUT and DET open DUT connector the DUT connector read OPEN Mode 1 8 Mode2 Start frequency Hz Stop frequency Hz aj Ds of Overscans i 100 000 69 999 999 ae ee calibration steps 2 000 70
40. he SPDAQ processes see Appendix B 1 T dropbox uploader sh Dropbox shell script to upload sp dat file to a linked Dropbox account on the RPi2 see Appendix put2str exe processes the exported CSV files from the miniVNA PRO see Appendix B 2 Y button py button and LED function on the Raspberry Pi 2 see Appendix C mE Specific packages also need to be installed onto the RPi2 for the files to run properly on the Arch Linux OS The following commands shown in Table 5 M can be executed on the RPi2 terminal with Arch Linux installed Ensure that the RPi2 is connected to the Internet in order to download these packages Once the packages are installed the MVP s software requires specific directories to be created These directories are created when the vnaJ hl 3 1 3 jar file is executed for the first time which can 48 Microwave Imaging of a Grain Bin 5 3 Software Setup and Configuration Table 5 111 Required packages to be installed on Arch Linux OS running on the Raspberry Pi 2 Command Description pacman S jdk7 openjdk Java package pacman S mono C Compiler pacman S python raspberry gpio Raspberry Pi GPIO Python library be executed using the following command java Deconfigfile gbin ml Dfstart 70000000 Dfstop 100000000 Dfsteps 100 Dealfile gbin cal Dscanmode TRAN Dexports csv jar unaJ hl 3 1 3 jar An error will occur due to certain files missing when the command is executed for the first time
41. he manufacturer did not have any indications that they will make this device open source This forced our team to go ahead with the manufac turer s software in order to use the MVP despite the slow read times of each measurement kathy nguyens macbook pro grainbin Running vnaJ hl 3 1 2 jar 4 Mar 2015 6 26 04 4 Mar 2015 6 26 04 4 Mar 2015 6 26 04 4 Mar 2015 6 26 04 PM version runtime vm version vm vendor version g Application versio PM T krause PM T krause PM T krause rause knguyen test sh vna data VNABandMap vna data VNABandMap vna data VNABandMap vna data VNABandMap load entry oad File read oad Ranges sorted load exit 1 8 0_25 1 8 0_25 b17 25 25 b02 Oracle Corporation x86_64 Mac OS X 10 10 2 US en 3 1 3 2015 02 13 knguyen User home User dir Installation dir Configuration dir Configuration file Serial library version start frequency stop frequency frequency steps tiscan mode 1 calibration 1 Device driver comm port frq range Calib blk loaded with Scanning range 0 of scan completed 0 of scan completed 100 of scan completed Data exported to Users knguyen Users knguyen Users knguyen Users knguyen vnaJ 3 1 config Users knguyen vnaJ 3 1 config myvnasettings xml 0 0 17 SpareTimeLabs 70000000 100000000 100 Transmission TRA
42. l of 24 antennas The 4 x 2 matrix switch chosen for this design was from Hittite Microwave Corporation part number HMC596LP4 and the SP3Ts chosen were part number HMC245QS16 also from Hittite Microwave Corporation This design was chosen for its simplicity which would allow for good performance However we were not able to use this design as it was realized that the 4 x 2 matrix switches chosen do not operate in the frequency range needed for our project of 70 9 MHz More research 25 Microwave Imaging of a Grain Bin 3 1 RF Switch was done but no switches of this type were found that operate in the required frequency range for this project Due to this limitation a new design was chosen consisting of a series of cascaded RF switches including SPDTs SP3Ts and SP8Ts The topology of this design is shown in Figure The switches used in this design are HMC349MS8G HMC245QS16 and HMC253Q524 from Hittite Microwave Corporation antenna 1 VNA antenna 2 Transmit VNA antenna 8 Receive Fig 3 2 Initial design of the multiplexer With this design decided on we needed to get it manufactured on PCB To create the PCB layout necessary to get these boards printed software package Altium was used Two boards were designed for the RF portion of the multiplexer one containing only an SP3T and one containing two SP8Ts and eight SPDTs The final 2 x 24 multiplexer requires two of the boards with SP3Ts and three of the boards with SP8T
43. less application 2015 Online Available ttp download dl2sba com vnaj manuals UserGuide headless pdf A Fabrizi Dropbox uploader 2014 Online Available https github com andreafabrizi Dropbox Uploader gt gt 56 Microwave Imaging of a Grain Bin REFERENCES 12 Pi gadgetoid com 2014 Raspberry pi pinout rev 2 board Online Available http pi gadgetoid com pinout 57 Microwave Imaging of a Grain Bin Appendix A Budget 58 Microwave Imaging of a Grain Bin Table A l Project Budget SYSTEM A Estimated Actual Order Status MODULE COMPONENT Supplier Part No Price Unit Quantity Sponsor Cost Order Cost Antenna PCBs Process of Antenna Array Metllicroda ElL 300 00 0 00 ordering Vector Network et Provided by EIL Analyzer VNA MiniVNA Pro 1 EIL 600 00 0 00 MUX DEMUX Digikey pi aaa 0 43 6 EIL 2 56 sooo Provided by EIL SMA board edge Digikey J502 ND 4 12 38 EIL 156 42 0 00 Provided by EIL SMA board edge Digikey pi ien 6 06 5 EIL 30 30 0 00 Provided by EIL 744 1374 Provided by EIL SMA SMA cable Digikey 9 40 6 EIL 5642 0 00 TOV e OY cap 10nF 0805 Digikey ers 0 34 50 EIL 16 79 sooo Provided by EIL 587 1133 6 Provided by EIL RF Multiplexer cap 100nF 0805 Digikey WE 0 16 100 EIL 16 06 0 00 ditis ey SPDT Digikey p
44. n HFSS but found the it would be too complex to build accurately and it would not be feasible to mount in the grain bin Mohammad Project co supervisor suggested the use of a 50ohm termination at the end of the loop to match the antenna to a 50ohm line and to cut the loop in half so that the size of it could be further reduced as well as to take advantage of having a metallic wall as the other half of the loop A prototype of this antenna was built using a semi rigid coaxial cable with a slot cut in the ground conductor and a 50 ohm termination was used to match the antenna to a coaxial line A difference of 10db was observed between the E and H polarization However building multi ples of such antennas accurately would not be feasible since the slot size would vary and produce inaccurate results as well as the curvature in the antenna is tough to reproduce accurately In order to make the antenna easy to manufacture and reproduce it was decided that a PCB version would be best suitable 16 Microwave Imaging of a Grain Bin 2 2 H field Antenna Fig 2 16 prototype antenna 2 2 4 PCB Antenna Design To achieve a shielded coaxial line on PCB a groundless co planar waveguide was chosen due to material availability 0 8mm FR 4 material was chosen as the PCB material with a relative permittivity of 4 3 Due to the limited capabilities of the PCB prototyping machine available at the EIL lab a minimum cut in the PCB could not exceed 0 2mm
45. nce manufactured should be a simple transition The work to be done once our RF Mux PCBs arrive will be to solder the RF switch integrated circuits ICs and to test with the rest of the SPDAQ Alpha prototype In terms of the DC switch an addition that will simplify this automated process between the Raspberry Pi by and the DC switch even in the case of software failure would be by using a Serial Peripheral Interface SPI via a GPIO for the handshake process This extended SPI communication will create more ports for the Arduino to use as well as provide a means for the software to not only talk to the Arduino but also receive interrupt flags from the Arduino which can help in auto troubleshooting should anything go wrong during the process of data acquisition 6 3 Antennna The H field antennas have been designed and tested For the future the E Field antenna design will need to be modified in order to reduce cross polarization so it can meet the SPDAQ system standards for a grain storage unit Once modified further tests need to be conducted with the antenna integrated with the SPDAQ system 53 Microwave Imaging of a Grain Bin Chapter 7 Conclusions The purpose of this project was to design a portable and affordable system for detecting moisture inside a grain bin using microwave imaging techniques There were several different components comprising this system Two types of antennas were studied H field and E field antennas
46. nna without shielding E field magnitude distribution in the cross sectional area 18 Microwave Imaging of a Grain Bin 2 2 H field Antenna HESSDesignt A XY Plot 1 Curve inte A aa NM pum an Sap Geo 250 500 7 50 10 00 35 8 1250 1500 1 50 20 00 2250 T T T T T T T T T T T T T o 10d 00 ado Pm mm 0800 Freq MHZ Fig 2 18 S11 simulated Fig 2 19 S11 of actual antenna 19 Microwave Imaging of a Grain Bin 2 2 H field Antenna Fig 2 20 E distribution with shielding Fig 2 21 E distribution Shielding removed 2 2 7 PCB Layout After simulating the antenna in HFSS the design was transferred to Altium which was used to create the necessary Gerber files for fabrication The antenna was fabricated in the EIL with the use of the rapid PCB prototyping machine 20 Microwave Imaging of a Grain Bin 2 2 H field Antenna Fig 2 22 fabricated antenna 2 2 8 H field Antenna Testing The antenna s ability to reject the Electric field was tested in a G TEM cell The G TEM cell creates transverse EM waves guided between a pair of plates with H orthogonal to E the incident wave was created with a signal generator producing an 80 MHz sine wave with 0dbm power and the AUT measurements were taken with a spectrum analyzer Two orientations of the antenna were tested in the cell longitudinally parallel with the magnetic field E orientation and perpendicular to magne
47. ode slower than expected and could easily pose problems for anyone who was not familiar with using multidimensional tables The software was enhanced and improved by first by connecting the Arduino to a breadboard and sending it the initial start instruction And observing on the board that the right control parameters was being set for the RF switch via the automated Arduino function The goal of the software side of our project is to get the Raspberry Pi to send a specific number which would correspond to one of the antennas and this will be used for transmission of the signal This would cause the the Arduino will set the parameters for transmission via that antennae and would be followed by a series of code setting the parameters from the reception of the signal via the remaining twenty three antennas Thus after one transmission via serial input the Arduino would receive twenty three reflected signals via serial without having to call the send any loops for the receiving signal A few scenarios posed during our troubleshooting sessions brought about the need for this more robust code to be written to the Arduino Firstly we were going to be use our devices on farm and chances are the farmers will not have the expertise to trouble shoo when something goes wrong There were different implementable codes written to address these potential issues However the synchronization between the Arduino software and the Raspberry Pi made this almost impossible
48. onnect the RF Multiplexer RF Mux and MVP As well the RPi2 offers GPIO pins which will be used to integrate user interface UI features for the user to have better control of the system Such UI features that were implemented with the RPi2 was a button to run the SPDAQs software when pressed and a LED indicator to allow the user to know when the program is ready for the user to press the button A circuit is shown in Figure 42 Microwave Imaging of a Grain Bin 5 2 Software Design and Integration 5 1 that displays the button and LED connection to the appropriate GPIO pins on the RPi2 see Appendix C for Raspberry Pi 2 Pinout Configuration GPIO17 Raspberry Pi 2 LED GPIO23 Push Button R1 R2 2200 2 2kQ Fig 5 1 LED and Button Circuit Initially the SPDAQ system was designed around the Raspberry Pi Model B but due to the new release of the RPi2 in February 2015 the decision to upgrade seem obvious with the faster processor at the same low cost of 39 99 CAD shipping that the old Raspberry Pi Model B was priced at The hardware upgrade helped greatly improve the software run times down to 16s per measurement to 5s per measurement Boot up times for the system also greatly reduced to 6s from 15s 5 2 Software Design and Integration Arch Linux was installed onto the RPi2 due to its minimal architecture It is a lightweight operating system OS that is text based with no GUI making it very quick to boot up
49. or both VNAS o o 40 40 4 4 miniVNA PRO Software Output 22r 41 5 LED and Button Circuit e sses s ee 43 5 2 S Parameter Data Acquisition system processes e 4 44 5 3 Flow chart of the Data Acquisition Process o 45 A a Pe GS d 46 rr 67 c cT a ee ag ee aM ae estes GENE Hee Gees ab ee ahs 69 ix Microwave Imaging of a Grain Bin LIST OF TABLES List of Tables 2 specification of the E filed antenna aa 3 AID VNA Requirements tl arm SR OE eke de cba e Erde See ears 38 TETTE 38 5 1 Raspberry Pi 2 Specifications 8 aa 42 I 48 48 Gf aha Gig O os a ee ee Gee 50 b td Be oS ee 51 So ete a eB Dak Ge L Cr cx 59 Microwave Imaging of a Grain Bin List of Abbreviations List of Abbreviations Abbreviation RPi2 SPDAQ MVP RF mux MWI Description Raspberry Pi 2 S Parameter Data Acquisition miniVNA PRO RF multiplexer Microwave Imaging xi Microwave Imaging of a Grain Bin DEFINITIONS Definitions VNA RF PEC PCB EIL EM ESD TEM HFSS PC IC Vector Network Analyzer Radio Frequency Electric Magnetic Wavelength Perfect electric conductor Printed circuit board Electromagnetic Imaging Lab Electromagnetic Electrostatic discharge Transverse electric magnetic High frequency structure simulator Personal computer Integrated circuit xii
50. ower 6 Ground 8 GPIO 14 TXD 10 GPIO 15 RXD 12 GPIO 18 PCM C 14 Ground 16 GPIO 23 18 GPIO 24 20 Ground 22 GPIO 25 24 GPIO 8 CEO 26 GPIO 7 CE1 28 ID SC 30 Ground 32 GPIO 12 34 Ground 36 GPIO 16 38 GPIO 20 MOSD 40 GPIO 21 SCLK Fig C 1 Raspberry Pi 2 Pinout 12 Microwave Imaging of a Grain Bin Appendix D DC Switch Lookup Tables EN Rx Thad SPST Tx 01 0 1 1 0 0 0 1 61 e 1 1 1 1 1 1 EN Rx Second Row SPST Tx EN First Row SPST Tx Rx 0 0 1 Tx YO ports 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 33 39 40 41 42 43 44 45 46 47 43 49 Control ne A B CDEHFGINIL H AAKO E2 F2G2 I2 DD I2 K2 I2 E3 F3 G3 H3 H3 H3 K3 03 RF1 Tx Row Select 0 0 B 0 0 0 0 B 1 1 1 1 1 1 1 1 0 0 0 0 0 0 0 RF2 Tx RF3 Tx RFA Tx RFE5 Tx RF6 Tx RF7 Tx RFS Tx RF9 Tx RF10 Tx RF11 Tx RF12 Tx RF13 Tx RF14 Tx RF15 Tx RF16 Tx RFL7 Tx RF138 Tx RF19 Tx RF20 Tx RF21 Tx RF22 Tx RF23 Tx RF24 Tx Microwave Imaging of a Grain Bin wi wi wi wi wi wi wi wi wi wi mw wi w mi O 1g gr ey 09 d 3 te tr tf 19 ty 922 01 1 1 8 Se Qm m mm 1 1 1 1 1 1 1 1 I 1 1 e 1 1 1 1 1 1 1 1 os DEE DES DES ESS DEE or or or or EA vr dr dr t or or rj ay ay ed or E E t ng or or or or org ordo so ror dr t or or rj ay ey ey or sr t or gr n ror orn rg ep ay ror ey t or or
51. s and SPDTs The final PCB layout of the two boards is shown in figures and 26 Microwave Imaging of a Grain Bin 3 1 RF Switch antenna 1 VNA Transmit antenna 2 VNA Receive antenna 8 Fig 3 3 Final design of the multiplexer Fig 3 4 PCB layout for SP3T board 27 Microwave Imaging of a Grain Bin 3 1 RF Switch Fig 3 5 PCB layout for top layer of SP8T and SPDT board Both boards were designed with 4 layers using a substrate of FR 4 The stack up of the boards consists of a top signal layer followed by a substrate layer then an internal signal layer used only as ground in this design and then the prepreg layer Below the prepreg layer is a mirror of what is on top of it an internal signal layer then substrate layer and then bottom layer The stack up from Altium is shown in Figure 3 7 28 Microwave Imaging of a Grain Bin 3 1 RF Switch Fig 3 6 PCB layout for bottom layer of SP8T and SPDT board Dielectric Dielectric Layer Name Type Material Thickness mM Material Constant Pullback mm Orientation Top Overlay Overlay Top Solder Solder Mask Co Surface Material 0 01016 Solder Resist 3 5 E EB NN NS NS E HE ropa Signal Copper 0 03556 Top PP Dielectric Dielectric Ewe los FRA laz E E EH EUH UN EU UN Signallayeri Signal Copper 0 03 E 7 Not allowed Prepreg Dielectric Prepreg 0 127 FR4 42 Em m NE NE NE NN signal tayer
52. s by the sum of Ls NLm where N is the number of meander sections In order to exam the resonant behavior of the meandered line antenna we will simulate and use optimism method in HFSS to compare each group of meandered antenna parameters given above MO to M5 configurations shown in Figure Best Morrow is applied to observe the variation the resonant frequency of the antenna 2 3 The MO configuration has a self resonant frequency at S0MHz while the M5 configuration Microwave Imaging of a Grain Bin 2 1 E field Antenna Fig 2 2 meandered monopole antenna geometry has a self resonant frequency at 110MHz For antenna represented in 2 1 s is equal to 1cm L is equal to 4cm using equation 2 2 and 2 3 and the value of Lm is calculated as about 300nH a comparison table of resonant behavior of different numbers of section is listed in Figure 2 3 HFSS simulation result a Resonant frequency MHZ 2 eo oo 5 S N o o 0 1 2 3 4 5 number of meandered sections Fig 2 3 Resonant frequency of meandered line antenna MO to M5 From Figure it is evident that the inductor circuit model representing the meandered antenna provides an acceptable prediction showing a liner increase in resonant frequency as a function of increasing bending sections however in the real case the resonant frequency of the meander line antenna will not linearly increase with the number of sections 2 3 Microwave Imaging of a Grain
53. s of the parameters given above In these cases it is predicted that the inductor circuit model will not be adequate for explaining the relative changes of the resonant frequencies Since the self resonant frequency of the simple straight line monopole antenna can be modeled as the inductor circuit model we can use the formula to calculate the self inductance when the total physical length of the antenna is about 4 Microwave Imaging of a Grain Bin 2 1 E field Antenna ES pan Fig 2 1 equivalent model of meander line sections 0 2384A Ls 0 2384M In 4 1 2 1 Where d is the diameter of the radiator of the antenna and A is the required resonant wave length the resonant frequency of the antenna can be estimated using an inductor circuit model representation as introduced in Figure 2 1 To determine the inductance in each meandered section we will use an equivalent transmission line model which has a characteristic impedance given as 2 Z5 2T6log 7 2 2 where s is the spacing between each meandered section as a result the equivalent inductance of each section Lm is given as following u Zotanh 1 i tJ Lm 2 3 Where is the propagation factor of free space l is the length of each meandered section and is angular velocity the resonant frequency of the meandered line antenna should have same physical length as the simple straight line monopole antenna but we need to replace the equivalent inductor L
54. t that most of the design should be implemented in the PCB in order to reduce complexity and make troubleshooting easier This also ensure a reduction in noise cause by all the numerous wiring and addition electrical components that was everywhere Figure 3 8 highlights that function of the DC switch in perfect simplicity The control param eters are letters from A to L and these are sourced from the DC switch to the SP3Ts SP3Ts and SPDTs of the RF switch 31 Microwave Imaging of a Grain Bin 3 2 DC Switching Fig 3 8 Topology for the integration between DC and RF Switches Designing the PCB first started with the schematic and a review of the schematic to ensure its accuracy Figure is the initial schematic that was used in the printing of the PCB in Altium This was designed to be efficient and less complicated however the simplicity brought about some complication when it was being integrated with the RF Switch Using an Arduino board the previous schematic was put to the test It proved to work in every sense of the word without any glitches It carefully selected that right control parameters and turned the respective led pins on which meant theoretically we had a good hardware and software The simplicity of the first designed was questioned when the second version of the RF switch design was completed and had a similar schematic design as the previous design This implied that the new improvements made to the design which
55. targetDirectory tt cesy if fileEntries Length 0 Console WriteLine ERROR No files in directory to process else int count 0 foreach string fileName in fileEntries x string dataID Path GetFileNameWithoutExtension fileName string tx datalD Substring dataID Length 4 2 string rx datalD Substring datalD Length 2 2 sp count 0 tx sp count 1 rx Console WriteLine TX O tRX 1i sp count 0 sp count 11 ProcessFile fileName count count Insert logic for processing found files here public static void ProcessFile string file int count string lines System 1I0 File ReadAllLines file string data 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 OCOANOATAKBWN EH el ON oneone Cc Microwave Imaging of a Grain Bin B 3 button py foreach string line in lines Skip 1 f string val line Split double double double double a double b magdb Convert ToDouble val 1 ph Convert ToDouble val 2 mag Math Pow 10 magdb 20 mag Math Cos Math PI ph 180 mag Math Sin Math PI ph 180 data string Concat data Nt b ToString N7 t sp count 2 data Console WriteLine Processed file gt LO es string Concat a ToString N7 file B 3 button py Code B 3 Button and LED function on Raspberry Pi 2 import RPi GPIO as GPIO from time import sl
56. th the RPi2 through an Ethernet connection with another device e The RPi2 is assigned a static IP address for the user to SSH and SFTP in order to communicate with it That static IP address is 192 168 2 23 Once SFTP establishes a connection executing the command get root grainbin output sp dat will transfer the file over to the users remote device 4T Microwave Imaging of a Grain Bin 5 3 Software Setup and Configuration 5 3 Software Setup and Configuration This chapter section details the software setup and configuration on the RPi2 to run the SPDAQ software The purpose of this section is to help a user recreate the SPDAQ software on the RPi2 in the case of any software error or corruption or to simply modify specific software parameters to tailor to the user s needs 5 3 1 Prerequisites The RPi2 is setup with a username and password The default login information for Arch Linux is the following Username root Password root However for security purposes the password was changed to gbin2015 with the same username In order for the RPi2 software processes to function certain files need to be included on the RPi2 stored in the directory root grainbin A list of these files is shown in Table Table 5 1I Required files in the root grainbin directory of the Raspberry Pi 2 File Description vnaJ hl 3 1 3 jar miniVNA PRO headless software gbin sh shell script t run all of t
57. tic field H orientation Absorbant 10x10 cm opening lt LY SN MM Z Mi ws N m zm 9 a 3 o Fig 2 23 field lines in G TEM for reference 21 Microwave Imaging of a Grain Bin 2 2 H field Antenna 2 2 9 G TEM Test Results The noise floor of the antenna was measured at 83dbm with incident power of 13dbm When oriented in the E orientation the antenna received 81dbm which is close to the noise level of the antenna when oriented in the H orientation the antenna received 65dbm therefore a difference of 16db exists between the two orientations which shows that the antenna is picking up only H field Fig 2 24 E orientation 22 Microwave Imaging of a Grain Bin 2 2 H field Antenna Fig 2 25 H orientation 23 Microwave Imaging of a Grain Bin Chapter 3 Multiplexer The multiplexer consists of two sections an RF switch section and a DC switch section The RF switch provides a path for the signal to and from the VNA to the antennas while the DC switch provides the logic necessary to set the correct path in the RF switch at the correct time In order to collect the data required to create an image of the grain bins contents an array of antennas needs to be connected to the VNA Figure 3 1 shows how the multiplexer connects the VNA to the array Of antennas The VNA has two ports one which transmits a signal and one which receives a signal Through
58. to accomplish It was considered that either the Raspberry software of the Arduino software should be capable of automated function once the start button is push or a signal is sent to a pin in order to make 35 Microwave Imaging of a Grain Bin 3 2 DC Switching starting the data acquisition and stopping the running routine easily understood to the average farmer 3 2 2 ESD Protection Any reliable system design requires some form of Electrostatic Discharge protection Choosing the right circuit protection device involves considering criteria such as Response time ESD current handling capacity and maximum reverse leakage current Also the device should not interfere with the normal operation of the circuit Designing the DC circuit also meant taking the RF circuit into consideration in order to minimize electrostatic discharge and current leakage We considered N well resisters gate grounded and gate coupled protection options silicon con trolled rectifiers and diodes Ultimately we decided to use diodes and capacitors due to its simplicity During our design phase the options available were to implement ESD protection on the antenna or on the switch box We chose to go with ESD protection for the switch box because it was less expensive to do it that was and it was a trusted and proven route to for to ensure that a great amount of ESD is dealt with in our circuit There is no addition intended for the ESD protection The data sheet
59. uploader sh Follow the instructions on the screen to create a new Dropbox app on your account from another web browser Copy the app key and app secret given by Dropbox after filling out the create a new app form to the terminal window that is running the Dropbox shell script If the given information is correct you will receive a oAUTH URL to enter into your web browser to verify app access to your Dropbox Dropbox on the Raspberry Pi 2 is now linked to your account See below for Dropbox commands that can run on the Raspberry Pi 2 B 4 2 dropbox uploader sh Commands file folder gt is a required parameter file folder is an option parameter 65 Microwave Imaging of a Grain Bin B 4 Dropbox Setup on the Raspberry Pi 2 dropbox uploader sh upload lt LOCAL_FILE DIR gt lt REMOTE_FILE DIR gt dropbox uploader sh download lt REMOTE_FILE DIR gt LOCAL_FILE DIR dropbox uploader sh delete lt REMOTE_FILE DIR gt dropbox uploader sh move lt REMOTE_FILE DIR gt REMOTE_FILE DIR dropbox uploader sh copy lt REMOTE_FILE DIR gt REMOTE_FILE DIR dropbox uploader sh mkdir lt REMOTE_DIR gt dropbox uploader sh list lt REMOTE_DIR gt dropbox uploader sh share lt REMOTE_DIR gt dropbox uploader sh info dropbox uploader sh unlink 66 Microwave Imaging of a Grain Bin Appendix C Raspberry Pi 2 Pinout 3100 GPIO 9 MISO GPIC GPIO 19 M GPIO 2 Sv Power 4 Sv P
60. utions This project aims to create an affordable and user friendly solution for the detection of spoilage and moisture of grain inside of an industrial grain storage bin This can be achieved through microwave imaging of the contents of the bin and reproducing a three dimensional image of the different dielectric contents of the bin A typical microwave imaging system consists of a VNA an RF multiplexer an array of antennas and a data acquisition and processing unit The design and testing of these individual components was distributed among the group members as described below Another major contributor to this project was PhD student Mohammad Asefi who worked closely with our group and provided helpful academic and technical advice Microwave Imaging of a Grain Bin gt o 2 2 g gt E 1514 ES a R2 5 e0 o mM a Z E lt o S 3 5 gt gt s E Bd 9 2 A Electric field antenna design simulation and testing o Magnetic field antenna design simulation and testing e Raspberry pi user interface and automation software e VNA control software e RF component of multiplexer PCB design and layout e DC component of multiplexer PCB design and layout e Multiplexer address decoding e ESD protection o e VNA and RF multiplexer Performance testing o o Legend Lead task O Contributed 111 Microwave Imaging of a Grain Bin ACKNOWLEDGMENTS Ackno
61. within the array that the MVP measured from The MVP exports the data as transmission loss in dB and transmission phase degrees which is S12 in polar form however Cartesian com plex form is required for post analysis and therefore a small calculation is required prior to writ ing to file The calculations performed are described below The MVP provides its data as so 45 Microwave Imaging of a Grain Bin 5 2 Software Design and Integration TransmissionLoss TL 20 log o S12 TransmissionPhase 0 The desired data form is as so 12 a bi Variables a and b are calculated as shown a S12 cos8 b S12 sind where 12 1012 20 Once the 12 data is calculated to Cartesian complex format it is then written to a file called sp dat which is located in root grainbin output directory The format of the file is shown as Tx Rx Probe S12 Real S12 Imaginary repeating for all frequency steps Where Tx is the transmitter antenna number and Rx is the receiver antenna number which is then followed by the 12 real and imaginary data in succession for all 100 frequency steps A flow chart of the Post Data Processing procedure is shown in Figure 5 4 5 2 4 Data Transmission Process The sp dat file contains all of the S parameters of the grain storage unit and this file will be accessible to the user through the cloud if an Internet connection is present The shell script will execute the data upload process after the Post
62. wledgements We would first like to thank our academic supervisors Dr Joe LoVetri and Mohammad Asefi for providing us with constant technical and academic help and support throughout the duration of the project and for providing us with access to necessary equipment materials and parts required for this project Thanks to Zoran Trajkoski with helping us with all of our PCB antenna prototyping and support thank you to Sinisa Janjic with part ordering We would also like to thank Paul Card and Colin Gilmore our industry sponsors at 151 Research Inc with the opportunity to work on this project Microwave Imaging of a Grain Bin TABLE OF CONTENTS Table of Contents ene Be He Oth Be a Se on es ee eh oe e i Contributions e e e a Soe wk ER a ia a rd a a ee aw ae Ee Bae ii ease RURSUS TREE peas toca said iv KETTE viii isto bables 2 x 42 g a Sep eo eA or kom p RUXUR a RERBA OX Sx Rm he we ek us x List of Abbreviations 2l ss xi Ob be RE oY ROS ee AAA AR Rea RTI xii OG Se Ba eee oo NA ee ee ee Eee 1 uico GOR ARE HES Rubr EE SR oe Dae oh dak ba eae eh ba ee 1 LT TL 1 TT TP 2 2 Antennas 42 2 9 on s 9o oon OR E REG RUE OA REO EO OR Re OR Roos 3 te Bat ee ee ee gp ee a ee ee 3 bee Ran FG ame ee A DOR a 4 2 1 2 Antenna Building and Testing a 9 he Boba ee oe Hg TUTTI 14 se dog A eee ete ee A GS doe Ss A oe Rw Ge i 14 2 2 2 Research 2 ose 9 2 ae Roe o o Rm ee EE RO OS S E a aes 15 Tr TT

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