Manual - ETS
Contents
1. 3 Model 3115 Double Ridged Waveguide Horns e 1 Model 3102 Conical Log Spiral The log spiral is installed in the ceiling of the chamber supported by an N f f adapter and the two SISO horn antennas are mounted in the side walls and on the turntable Following are photos of typical antenna installation and absorber placement TYPICAL ANTENNA INSTALLATION AND ABSORBER PLACEMENT aA Model 3115 Double Ridged Waveguide Horn 38 Assembly ets lindgren com Model 3115 Double Waveguide Horns Model 3102 Conical Log Spiral ets lindgren com Assembly 39 AMS 7000 Illustrations AMS 7000 FRONT 2081mm 81 92in 2005mm 78 92in INSIDE 2052mm 80 81in 40 Assembly ets lindgren com AMS 7000 LEFT SIDE 1200mm 47 24in INSIDE 1254mm 49 38in 1500mm 59 06in INSIDE NK 1 er WW e ets lindgren com Assembly 41 AMS 7000 RiGHT SIDE 1394mm 54 87in 42 Assembly ets lindgren com Appendix A Warranty Note See the Product Information Bulletin included with your shipment for the complete ETS Lindgren warranty for your AMS 7000 Duration of Warranties All product warranties except the warranty of title and all remedies for warranty failures are limited to the durations outlined below for each product Product Warranted Duration of Warranty Period ets lindgren com Warranty 432. 34 Eet EEN 35 Requirements for TIS Measurement 35 Hardware Configuration for TIS Measurement 35 Procedure for TIS Measurement Woo oom 36 7 37 ialleje e LEE 37 Antena ee rere 38 Typical Antenna Installation and Absorber Placement 38 AMS 7000 Ill SttallOriS EE 40 AMS 7000 FrOM Aa Sects Seis een he toi 40 le ET 41 AMS 7000 Right Side EE 42 Appendix ET 1 TE 43 Duration of Warranties niatan anakin 43 IV ets lindgren com Notes Cautions and Warnings Note Denotes helpful information intended to provide tips for better use of the product Caution Denotes a hazard Failure to follow instructions could result in minor personal injury and or property damage Included text gives proper procedures Warning Denotes a hazard Failure to follow instructions could result in SEVERE personal injury and or property damage Included text gives proper procedures Note See the ETS Lindgren Product Information Bulletin for safety regulatory and other product marking information ets lindgren com This page intentionally left blank vi ets lindgren com 1 0 Introduction The ETS Lindgren AMS 7000 Series Reverberation Chamber Wireless Measurement System is designed to measure the over the ai
3. REQUIREMENTS FOR TRP MEASUREMENT Communication Tester Spectrum Analyzer optional e EMQuest EMQ 200 Reverb OTA Antenna Measurement Software e Correction files created and saved during the Chamber Calibration process EMQuest Control PC Communication Tester 2929 tes 1 Spectrum Analvzer Loss corrected RF cable RF Cable GPIB Cable RS232 Cable ets lindgren com Measuring TRP TIS for SISO Systems 31 HARDWARE CONFIGURATION FOR TRP MEASUREMENT 50 termination Communication Tester amt 87 1 5 TT WER 18 TTY 444 RF in Out Tuner Control RF Cable 5232 Cable sm GPIB Cabe m m m RF Cable with measured Loss 32 Measuring TRP TIS for SISO Systems ets lindgren com PROCEDURE FOR TRP MEASUREMENT This measurement can be done in step mode or continuous rotation In both cases the turntable will rotate the DUT to different positions as the two tuners are rotated Place the Device Under Test DUT on the edge of the turntable in one of the slots provided 1 Place the DUT as shown DUT 1 Communication Anywhere on the edge 2 m E im Im Horizontal Tuner Styrofoam Column DUT Placement under Communication Antenna on Smallest Side 2 Connect the output of the communication tester to
4. The modes that are supported in the chamber are a function of the frequency of the injected signal and the dimensions and the Q of the chamber affects the magnitude of the resonance This may be at a single CW frequency with a limited number of modes available in the chamber When the bandwidth of the chamber is taken into account however it becomes possible for a single CW frequency to excite a number of adjacent modes resulting in increased mode density The distribution of the signal maxima in the chamber is fixed spatially if the cavity properties remain static If the boundaries or frequency content are changed then with the resulting movement of these maxima a statistically homogenous and isotropic environment can be realized ets lindgren com Introduction There are several methods that be used to make the changes to the boundaries of the cavity and each method has merit based mainly on ease of automation simplicity and overall effectiveness for a particular measurement type Most of the existing EMC test standards that describe a test method based on reverb chambers refer to the use of a mechanical reflecting structure that is either stirred continuously or stepped The design of a reverb chamber depends on the application and there can be differences in the implementation of many of the design components that result in one or another of a chamber s attributes being optimized Reverb chambers have become a very useful tool for
5. VNA Run the measurement taking at least 100 sweeps data points at each frequency for different tuner positions 300 tuner positions recommended If running continuous mode select 7 for the turntable and 1 8 8 turntable to tuner ratio 8 Afterthe test is done the saved raw data file will be used as a correction for TRP and TIS measurements in the respective frequency bands 9 Set up anew Response Measurement parameter file in EMQuest for 521 measurement 10 Measure the loss for the RF cable that will be used for TRP and TIS measurements This cable will connect the measurement antenna to the spectrum analyzer during TRP or RF in in the BSE and the RF out on the communication tester to the measurement antenna during TIS 11 Save the result in raw format this file will be used as a correction factor in TRP and TIS measurements 12 Since the calibration antenna is only used for the chamber calibration the losses of the antenna can be removed from the correction data applied to the TRP and TIS measurement This loss 0 34 dB can be added as a constant correction in EMQuest 28 Measuring TRP TIS for SISO Systems ets lindgren com ets lindgren com I 4 LL Sample S21 Data for a Loaded Chamber Measuring TRP TIS for SISO Systems 29 TABLE ABSORBER LOADING FOR DIFFERENT VALUES 1900 MHZ RMS Delay ns 434 30 Measuring TRP TIS for SISO Systems ets lindgren com TRP Measurement
6. immunity and shielding effectiveness measurements in the EMC community and have been gaining increasing popularity for use in the wireless community in recent years A suitably sized reverb cavity can be used to perform TIS and TRP over the air measurements of wireless devices with a level of accuracy and repeatability that can be on a par with other established alternative anechoic methods It can also be used to measure antenna efficiency as well as the throughput and diversity of MIMO devices with test methodologies being developed to support these measurements This document provides guidance on how to perform a calibration of the chamber and make TRP and TIS measurements for SISO technologies using the AMS 7000 Standard Configuration The AMS 7000 system consists of a reverberation chamber a communication test set Base Station Emulator a Vector Network Analyzer VNA and an EMCenter switch matrix under the control of EMQuest EMQ 200 Reverb OTA Measurement Software Other options are available to extend the operation of the system to support MIMO and Wi Fi testing 8 Introduction ets lindgren com ETS Lindgren Product Information Bulletin See the ETS Lindgren Product Information Bulletin included with your shipment for the following e Warranty information e Safety regulatory and other product marking information Steps to receive your shipment Steps to return a component for service ETS Lindgren calibra
7. is measured and compared to a reference measurement taken with the door open Because of the chamber size it is not practical to maintain the 1m separation of the measurement antennas and the 0 5m between the antenna and the chamber wall so the method is modified slightly to take advantage of the inherent resonant properties of the reverb chamber 20 Measured Performance ets lindgren com This modified method requires the maximum received level to be measured while the tuners in the chamber are rotated with the measurement receiver set to max hold This reduces the risk of standing waves patterns in the chamber giving an erroneously optimistic shielding value For the AMS 7000 the minimum level of SE is 100 dB in the frequency range of 700 MHz to 6 GHz This has been verified with this method ets lindgren com Measured Performance 21 This page intentionally left blank 22 Measured Performance ets lindgren com 6 0 Measuring TRP TIS for SISO Systems This section provides information on how to make Total Radiated Power TRP and Total Isotropic Sensitivity TIS measurements for Single Input Single Output SISO technologies using the AMS 7000 Series Reverberation Chamber Wireless Measurement System Three sets of instructions are included e Chamber Calibration e TRP Measurement TIS Measurement The AMS 7000 uses EMQuest EMQ 200 Reverb OTA Antenna Measurement Software ets lindgren com Measuring TRP TIS for SISO Syste
8. AMS 7000 Series Reverberation Chamber Wireless Measurement System User Manual WETS LINDGREN An ESCO Technologies Company ETS Lindgren Inc reserves the right to make changes to any products herein to improve functioning or design Although the information in this document has been carefully reviewed and is believed to be reliable ETS Lindgren does not assume any liability arising out of the application or use of any product or circuit described herein nor does it convey any license under its patent rights nor the rights of others All trademarks are the property of their respective owners Copyright 2013 2015 by ETS Lindgren Inc Rights Reserved No part of this document may be copied by any means without written permission from ETS Lindgren Inc Trademarks used in this document The ETS Lindgren logo is a registered trademark and EMCenter and EMQuest are trademarks of ETS Lindgren Inc Revision Record MANUAL AMS 7000 SERIES Part 399372 Rev B Reson mmm me Initial Release February 2013 Updated specifications and August 2015 illustrations ii ets lindgren com Table of Contents Notes Cautions and Warnings sees V 0 IntrodUCtiOn Ped 7 Standard COMO UAN ON nenen Ete ossa RN 8 ETS Lindgren Product Information 9 RE Tan ne am aan 11 Performance MOMIOMMG insan BEN SRS AS 11 Owner Operator Maintenanc
9. ainly of reflected components This antenna is used as the source to generate the field conditions in the chamber for the TIS measurement and also as the receive antenna to measure the power level in the chamber during TRP measurements The third antenna is a calibration antenna mounted on turntable and directed away from the DUT position This is used as a reference antenna for calibration of the chamber Before any measurements can be made the characteristics of the chamber must be measured This is done by measuring the transmission and reflection characteristics S parameters of the chamber relative to the antenna ports This data is then used to form a correction factor versus frequency dataset that can be applied to the measurements made in the chamber 18 Basic Theory of Operation ets lindgren com 5 0 Measured Performance The performance and operation of the reverberation chamber is based on the creation of a statistically uniform environment within acceptable uncertainty The uniformity of the test volume can be verified by direct measurement of the E field using a three axis field probe For this measurement the probe would be placed at different locations within the test volume in the chamber At each probe location the tuners are stepped to different angular positions or stirred continuously and the field components measured to provide the required number of data samples An alternative approach is to measure the variati
10. cy under different resonant conditions in the chamber The average of this is used to produce the correction for the chamber The following procedure can be used for basic chamber calibration 1 Perform a full two port calibration of the VNA at the antenna ports using the calibration kit LLL Ouest Control Vector Network Analyzer Calibration Reference RF Cable GPIB Cable R5232 Cable 26 Measuring TRP TIS for SISO Systems ets lindgren com m Um 18 in e E S E d SS 9 Calibration Points RF Cable RS232 Cable m m GPIB Cabe sm m m VNA Calibration at the Antenna Ports 2 Save the calibration on the 3 Connect Porti on the to Antenna1 measurement antenna and Port2 on the to Antenna2 reference antenna 4 Select the Reverberation Chamber Vector Calibration Measurement test option in EMQuest to measure the chamber loss o Note Steps 5 and 6 may change depending on the VNA used 5 Place six blocks of absorber around the floor of the chamber for measurement from 700 MHz to 1 GHz and seven blocks for measurements above 1 GHz 6 Setthe calibration option in EMQuest for the VNA to Manual ets lindgren com Measuring TRP TIS for SISO Systems 27 7 Perform the requested manual calibration and then recall the saved calibration on the
11. e Items ooooW Woo 12 Finger Stock GaSkel sm laman 12 Floor Connector ue dsn eta nenen asha 12 KEEN 12 ANISSZ00D Cleaning ari BR BS 12 ul 13 Service PhOCCOURES EE EE 14 Gontacting ETS LEindgren bos me eas 14 Sending a Component for Gervice WWW 14 Calibration Services and Annual Calibration 14 EIERE een 15 Elecireal ee ue EE 15 Tee el EE 15 Physical SpeciliCduOLlS EE 16 4 0 Basic Theory of Operation 17 5 0 Measured Performance oo mom 19 521 512 511 and 522 Measurement mee 19 Shielding Elec ET 20 6 0 Measuring TRP TIS for SISO Systems 23 C haiibsr CalibratlODissu Ee 24 Requirements for Chamber Calibration 24 Hardware Configuration for Chamber Calibration 25 Procedure for Chamber 26 Table Absorber Loading for Different PDP Values 1900 2 30 TRP EE TEE EN ets lindgren com Requirements for Measurement 31 Hardware Configuration for TRP 32 Procedure for TRP Measurement oW Woo WWW 33 Table Spectrum Analyzer Settings If
12. ing the pan formed panel technology that ETS Lindgren has used in full sized chambers for several decades The 2 mm thick aluminum panel sections that form the chamber are bolted together with a double row knit mesh gasket to provide better than 100 dB of shielding effectiveness across the 700 MHz to 6 GHz operating frequency range There is a single large 1 0m x 1 5m knife edge swing door based on the RFD 100 door design with an ergonomic vertical latching bar with free wheeling handle This provides easy access to the test area within the chamber There are two Z fold tuners fitted in the chamber one mounted vertically in the right corner and the other mounted horizontally along the left wall A turntable is located in the floor with the top of the turntable maintaining a flush internal floor surface The chamber is built on an integral support frame with locking castors which provide for easy movement throughout the test lab Shipping Crate o Note Contact ETS Lindgren for shipping crate dimensions The AMS 7000 is calibrated at the factory and shipped as a fully assembled unit in a single shipping crate The crate includes a removable side panel and ramp to provide easy removal of the AMS 7000 without the need for special lifting equipment ets lindgren com Assembly 37 Antennas The measurement antennas are removed for shipment to prevent damage during transit and will need to be reinstalled There are four antennas to be installed
13. mounted external to the chamber are fixed to the chamber wall and ceiling Each motor shaft passes into the chamber via a shielded penetration fitted to the chamber On all chambers the RF feedthrough assembly on the motor side of the tuner contains a large number of ball bearings Do not remove these they provide the HF shielding of the gear shaft as it passes through the shield ets lindgren com Maintenance 13 Service Procedures CONTACTING ETS LINDGREN Note Please see www ets lindgren com for a list of ETS Lindgren offices including phone and email contact information SENDING A COMPONENT FOR SERVICE For the steps to return a system or system component to ETS Lindgren for service see the Product Information Bulletin included with your shipment CALIBRATION SERVICES AND ANNUAL CALIBRATION See the Product Information Bulletin included with your shipment for information on ETS Lindgren calibration services 14 Maintenance ets lindgren com 3 0 Specifications Electrical Specifications DUT Motor Drive 1 Tuner Motor Drive 2 Line Input 110 220 VAC 220 VAC 50 60 Hz 50 60 Hz Single Phase Single Phase 750 VA max RF Specifications SISO TRP Test Type SISO TIS Test Type Frequency Range 700 MHz 6 GHz 700 MHz 6 GHz VSWR Typical S21 10 5 S21 10 5 S11 S22 1 75 511 522 1 75 RF Connector Type N adapter f N adapter f Shielding E field E field Effectiveness 100 dB minimum 100 dB minim
14. ms 23 Chamber Calibration REQUIREMENTS FOR CHAMBER CALIBRATION Vector Network Analyzer 1 L i SC Ste Antenna Antenna Mounted on ceiling GPIB Cable F5232 Cable e Vector Network Analyzer e Vector Network Analyzer Calibration Kit EMQuest EMQ 200 Reverb Antenna Measurement Software Hardware Configuration for Chamber Calibration 24 Measuring TRP TIS for SISO Systems ets lindgren com HARDWARE CONFIGURATION FOR CHAMBER CALIBRATION Calibration Vertical Tuner in 210027110 Tuner Control Ae Measurement Communication Horn Antenna Turn Table Antenna RF Cable 5232 Cable GPIB Cabe m m m ets lindgren com Measuring TRP TIS for SISO Systems 25 PROCEDURE FOR CHAMBER CALIBRATION Note As an alternative to the following procedure the AUTO calibration routine can be used from EMQuest Chamber calibration requires rotating the calibration antenna on the turntable for the different tuner positions A minimum of 100 different sweeps or traces taken over the operating frequency range of 700 MHz to 6 GHz is required to obtain accurate calibration coefficients Each sweep taken at a different position of the tuners and turntable represents a sample of the coupling between the two antennas at each frequen
15. nsuring proper operation of the system Protect these connectors with caps when they are not in use AMS 7000 CLEANING Overall cleaning of the AMS 7000 inner and outer surfaces may be performed by the use of standard non abrasive non corrosive cleaners Periodic cleaning of the interior with a vacuum cleaner will reduce the possibility of debris build up in the turntable area 12 Maintenance ets lindgren com TUNER ASSEMBLIES The AMS 7000 uses two internally mounted tuner assemblies driven from stepper motors mounted external to the chamber The tuners are manufactured using a single lightweight aluminum rod to support the Z fold section which provides the necessary reflective surface for effective mode stirring No maintenance of the tuner structure is required in normal use but the surfaces can be dusted or vacuumed periodically to maintain their appearance The tuners are supported at both ends by a coupling clamp at the motor end and a self aligning bearing at the other end Inspect these every month for signs of wear loose screws distortion or noise There is a grease nipple on the self aligning bearing that is factory lubricated and should remain maintenance free in normal use These should be checked periodically to ensure free smooth movement and that fixings remain secure or if there is evidence of noise to see if additional lubrication is needed Additional grease can be applied with a lever action grease gun The motors
16. ntenna Measurement Software e Correction files saved during the Chamber Calibration process HARDWARE CONFIGURATION FOR TIS MEASUREMENT 50ohm termination Tuner Control RF Cable RF Cable with RS232 Cable measured Loss GPIB Cable sm m m ets lindgren com Measuring TRP TIS for SISO Systems 35 PROCEDURE FOR TIS MEASUREMENT This procedure is very similar to TRP except that the downlink is through the measurement antenna 1 Place the DUT as shown DUT Communication Antenna Anywhere on the edge IT Horizontal Tuner Styrofoam Column DUT Placement under Communication Antenna on Smallest Side 2 Use the Reverberation Chamber Sensitivity Measurement test to perform the TIS measurement 3 When setting up the parameter file subtract both correction files generated during the calibration process 4 0 35 dB the constant area at the lower right corner of the Corrections tab This is a correction factor that reflects the loss of the reference antenna Same as for TRP 36 Measuring TRP TIS for SISO Systems ets lindgren com 7 0 Assembly CAUTION Before connecting any components follow the safety information in the ETS Lindgren Product Information Bulletin included with your shipment The AMS 7000 Series Reverberation Chamber Wireless Measurement System is manufactured us
17. on in the transmission characteristics of the chamber by treating it as a two port device A Vector Network Analyzer is connected to the two antenna feed ports on the chamber wall and turntable and the maximum 511 522 512 and S21 are measured while the tuners and turntable are rotated With this approach the calibration antenna can be moved to several discrete positions for each complete tuner rotation sequence and the variation in the S parameters compared for each location in the test volume In both these methods the boundaries of the chamber are changed through the rotation of the two tuners and the rotation of the receive calibration antenna or the E field probe which is positioned on the rotating turntable The second approach is much faster than the direct field method and can be used to provide additional information on the delay characteristics in addition to providing information on the ratio of the direct to indirect E field components in the chamber 521 512 S11 and S22 Measurement The measured S parameters can be used to calculate a number of the chamber parameters The coherence bandwidth of the system is found from multiple measurements made over a complete stirring sequence It is a function of the chamber configuration including the DUT and antennas as well as phantoms and test fixtures if any are used ets lindgren com Measured Performance 19 The easiest way to calculate the coherence bandwidth is
18. r OTA performance of a wireless device This can be used for measuring the Total Radiated Power TRP or Total Isotropic Sensitivity TIS of Single Input Single Output SISO devices RP is an emission type measurement with the device acting as a radiating source and the average power level in the chamber measured over a predefined set of the boundary changes e TIS is asensitivity measurement where an average power level in the chamber is established and the effectiveness of communication is tested as the power level in the chamber is reduced The sensitivity limit is determined when some predefined error threshold is reached by the device Reverberation chambers have been in use in the EMC community for several years with the main users being the military automotive and aircraft industries The reverb chamber has always provided what has been considered a severe and realistic environment for immunity measurements because the test field is all encompassing it exists in the entire chamber volume and not just in the illumination direction as is the case for anechoic chamber methods Reverberation reverb chambers are fundamentally a resonant cavity in which a number of Eigen modes are supported related to the dimensions of the chamber Each mode defines the spatial location of multiple maxima and minima in the chamber which if dense enough when stirred could provide an environment in which the E field maxima is uniformly distributed
19. rocedures The default time period between such evaluations this is not a calibration is six months ets lindgren com Maintenance 11 Owner Operator Maintenance Items FINGER STOCK GASKET Some mesh gasket material and finger stock is used in the construction of the AMS 7000 The finger stock in the door is accessible in the normal course of chamber operation Periodic visual inspections must be made to determine if there is need to clean the finger stock or to replace it if damaged Replacement finger stock for the doors is available from the factory replacement finger stock for the connector panels if used is also available Contact ETS Lindgren for more information To clean finger stock use an aerosol lubricant to loosen the debris and then low pressure air or another aerosol to remove the excess lubricant Alternatively a soft rag may be used to remove dirt and excess liquid from the finger stock FLOOR CONNECTOR PANELS The turntable feed through connector panel in the floor of the chamber will attract small particles of dirt or other debris Periodic inspection is required to ensure continued satisfactory performance To inspect for an accumulation of dirt the turntable top should be removed and a vacuum used for cleaning CONNECTORS The RF and other connectors are delicate in their wall turntable and floor mounted positions Periodic examination of these connectors for damage will prevent use of a damaged connector e
20. the communication antenna in the chamber ceiling Use the Reverberation Chamber Radiated Power Measurement test to perform the TRP measurement 3 When setting up the parameter file subtract both the Gret and Cable Loss correction files generated during the calibration process 4 Set the number of samples to 100 in the test parameter file ets lindgren com Measuring TRP TIS for SISO Systems 33 5 0 35 in the constant area at the lower right corner of the Corrections tab This is a correction factor that reflects the reference antenna loss 6 Ifa spectrum analyzer is being used Spectrum analyzer settings are dependent on the technology standard Use the following Spectrum Analyzer Settings table as a guideline TABLE SPECTRUM ANALYZER SETTINGS Ir USED Parameter GSM GPRS EGPRS TDMA CDMA WCDMA GMSK 8 PSK UMTS 300 kHz 300 kHz 300 kHz 10 MHz 10 MHz 8 MHz if 8 MHz if 10 MHz 10 MHz not not supported supported ii Points per 501 Trace RMS TDMA Pulse Average Integrated Pulse Trigger Video i Video Free Run Free Run Mode Trigger chose Floor chose Floor chose Floor NA Level 5 dB 5 dB 5 75 dB 75 dB Reference Level 34 Measuring TRP TIS for SISO Systems ets lindgren com Parameter GSM GPRS EGPRS WCDMA GMSK 8 PSK UMTS Flatness 20 dB Tolerance Filter Average TIS Measurement REQUIREMENTS FOR TIS MEASUREMENT e Communication Tester e EMQuest EMQ 200 Reverb OTA A
21. tion service ETS Lindgren contact information ets lindgren com Introduction This page intentionally left blank 10 Introduction ets lindgren com 2 0 Maintenance CAUTION Before performing any maintenance follow the safety information in the ETS Lindgren Q Product Information Bulletin included with your shipment WARNING Maintenance of the AMS 7000 is limited to the components as described in this manual other maintenance is not required Factory engineering personnel should be consulted in the event of damage or failure to operate properly after maintenance procedures If you have any questions concerning maintenance contact ETS Lindgren Customer Service Performance Monitoring On site S Parameter measurements are normally performed at the conclusion of installation procedures for the AMS 7000 Series Reverberation Chamber Wireless Measurement System They are also performed at the factory for all factory assembled chambers If the chamber is to be installed by an ETS Lindgren representative then the on site 5 Parameter measurement is the responsibility of the representative Determination of continued performance to specified parameters may be ensured by periodic re measurement of the Parameter This could detect changes in performance parameters that would signal unacceptable performance The measurement should be performed on a schedule as determined by the customer s Quality p
22. to 1 Determine the power delay profile PDP of the chamber The PDP is the IFFT of the average of a series of S21 measurement EMQuest Data Acquisition and Analysis Software provides time domain transform functionality under corrections for Reverb Chamber Vector Calibration Measurement This measurement can be accessed in EMQuest EMQ 200 Reverb OTA Measurement Software see the help file provided with EMQuest for more information 2 Perform the chamber calibration following the procedure described and click to select the Calculate Power Delay Profile check box This measurement should be done is 200 MHz wide bands using at least 1000 samples 3 A simplified coherence bandwidth can be measured as the inverse of the rms delay spread If the occupied bandwidth of the measured signal exceeds the coherence bandwidth the reverberation chamber must be loaded with RF absorbing material Loading the chamber is carried out iteratively until the coherence bandwidth exceeds the occupied bandwidth of the signal Eight blocks of HF absorbers are provided to be used to vary the loading of the chamber to adjust the PDP or bandwidth requirements Shielding Effectiveness The shielding effectiveness of the AMS 7000 Series Reverberation Chamber Wireless Measurement System is measured following the principles of the IEEE 299 method A transmit source is placed outside each of the walls of the chamber and the level of the receive signal in the chamber
23. um 700 MHz 18 GHz 700 MHz 18 GHz ets lindgren com opecifications Physical Specifications Note See AMS 7000 Illustrations on page 40 for additional measurements Height outside 2052 mm 80 81 in Width outside 2081 mm 81 92 in Depth outside 1394 mm 54 87 in Door Dimensions Width 1 0 m 3 28 ft Height 1 5 m 4 92 ft Nominal Test Volume in Length 0 9 m 35 4 in Center of Cell Width 0 9 m 35 4 in Height 0 6 m 23 6 in Distributed DUT Load Rating 11 36 kg 25 0 Ib 16 opecifications ets lindgren com 4 0 Basic Theory of Operation The AMS 7000 Series Reverberation Chamber Wireless Measurement System provides a resonant cavity fitted with two independently controlled mechanical tuners and a turntable The tuners are used to provide the boundary condition changes necessary to create variations of the spatial location of the E field maxima in the chamber The variation achieved with changes in the tuner position is limited by the number of modal variations available especially at the low frequencies close to 700 MHz and within the number of independent samples that are achievable With a significant number of boundary changes it is possible to realize an area within the test volume where field uniformity can be demonstrated to be uniform within some standard deviation In addition to the tuners there is a turntable fitted in the floor of the chamber it is used to support the De
24. vice Under Test DUT and one of the measurement antennas used only for calibration Rotating the DUT and calibration antenna provides added samples of the measured distribution through spatial sampling thereby reducing the uncertainty of measuring the maximum or the average of the E field in the chamber The location of the calibration antenna on the turntable close to the DUT ensures that similar statistics exist for this antenna during calibration and for the DUT during testing For SISO testing there are three antennas installed in the chamber e A log spiral antenna is mounted directly above the test volume to provide direct illumination of the DUT This antenna is used for communication with the DUT and is responsible only for maintaining the communication link during the rotation of the DUT The location directly above the DUT ensures that there is a dominant signal component irrespective of the orientation of the DUT which is not significantly influenced by the reflected components in the chamber as the tuners and turntable are rotated ets lindgren com Basic Theory of Operation 17 The main transmit receive antenna is fixed to a rotating turret assembly on the chamber floor and directed upward at approximately 45 degrees There is an added shielding panel positioned between the turret antenna and the turntable to minimize direct illumination of the test volume This ensures that the HF energy that arrives at the test volume consists m
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