This standard specifies limits and methods of measurement for radio disturbances in the frequency range from 150kHz to 1000MHz. This standard applies to any electronic/electrical component used in vehicles and large installations. The details of the frequency distribution in this standard refer to the International Telecommunication Union (ITU) publication. The limits in this standard are used to protect vehicle receivers from disturbances generated by components/modules in the same vehicle. Part 2 provides methods and limits for whole vehicle measurements, and Part 3 provides methods and limits for components/modules. Types of receivers to be protected are: sound and television receivers, land mobile communications, wireless telephones, amateur and civilian radio equipment. The vehicle in this standard is a self-propelled machine. Vehicles include (but are not limited to) passenger cars, trucks, agricultural tractors and snowmobiles. The limits in this standard can be selected by agreement between the vehicle manufacturer and the component supplier. This standard is intended for vehicle manufacturers and automotive electronic and electrical component suppliers. This standard does not include content for protecting electronic control systems from radio frequency (rf) emissions, transient voltages, and pulse voltage fluctuations. These contents are included in ISO publications. Since the installation position, vehicle body structure and wiring harness design affect the coupling of radio disturbance to vehicle receivers, the third part of this standard defines a variety of limit levels. The limit level used (as a function of the frequency band) must be agreed upon by the vehicle manufacturer and the parts supplier. In 1979, the World Regulatory Radiocommunication Conference (WARC) lowered the low-frequency limit of the first region to 148.5kHz. For new vehicles, the 150kHz test is sufficient. In this standard, the test frequency range has covered the radio service frequencies around the world. It is expected that in most cases, radio reception at adjacent frequencies can be protected. It is inferred that if the limits for business frequencies above 3OMHz are complied with, it is likely to provide protection for business frequencies below 3OMHz. GB 18655-2002 Limits and measurement methods for radio disturbance characteristics used to protect vehicle receivers GB18655-2002 standard download decompression password: www.bzxz.net

GB18655--2002
All technical contents of this standard are mandatory. Former
This standard is equivalent to the International Electrotechnical Commission/Special Committee on Radio Interference IEC/CISPR25:1995 "Measurement methods and limits of radio disturbance characteristics for protecting vehicle-mounted receivers". In Chapter 16 of this standard, for continuous emitters, the original text recommends the use of Level 5 in Band E and Band F, and this standard stipulates the use of Level 5 in Band E and Band F.
This standard is published for the first time.
This standard will be implemented after a transition period of one year from the date of promulgation. Appendix A of this standard is the appendix to the standard, and Appendix B, Appendix C, Appendix D, Appendix E, and Appendix F are prompt appendices. This standard is proposed by the National Technical Committee for Radio Interference Standardization. This standard is under the jurisdiction of the National Technical Committee for Radio Interference Standardization. The responsible drafting unit of this standard: China Automotive Technology Research Center. The drafting organizations of this standard include: Changchun Automobile Research Institute, Dongfeng Automobile Engineering Research Institute, Shanghai Volkswagen Automotive Co., Ltd., Shanghai General Motors Co., Ltd.
The main drafters of this standard include: Xu Li, Wang Wei, Lin Yanping, Yang Xiaosong, Wang Lian, Zhang Yifang. 204
GB18655—2002
IEC/CISPR Foreword
1) In view of the fact that each national committee and other member organizations of CISPR have some special interests in some technical issues, the formal resolutions or agreements on these technical issues drafted by the subcommittee express the consensus of international consultation as much as possible. 2) These resolutions or agreements are for international use in the form of recommended publications, and in this sense, they are accepted by each national committee and other member organizations of CISPR.
3) In order to promote international unification, CISPR hopes that all national committees should adopt CISPR recommended publications as their national standards if permitted by their own country. Any divergence between CISPR recommended publications and the corresponding national standards shall be explained as far as possible in the national standards.
Publication CISPR25 was prepared by the CISPRD Subcommittee on Interference from Motor Vehicles and Internal Combustion Engines. The content of this publication is based on the following documents: DIS
CISPR/D/(CO)25
Report on voting
CISPR/D/(CO)27
All information on the voting for the approval of this publication can be obtained from the voting reports listed in the table above. This publication will be amended and supplemented as practical experience continues to grow. Appendix A is an integral part of this publication.
Appendix B, Appendix C, Appendix D, Appendix E and Appendix F are for reference only. 205
GB 18655—2002
IEC/CISPR Introduction
This publication is intended to protect receivers from disturbances caused by conducted and radiated emissions generated in vehicles. The test procedures and limits given here are preventive controls for vehicle radiated emissions and are also effective for controlling long- and short-duration conducted/radiated emissions of components/modules. To achieve the above objectives, this publication: establishes a set of test methods for measuring electromagnetic radiation from vehicle electrical systems; sets a limit for electromagnetic emissions from the vehicle's electrical systems; establishes a set of test methods for on-board components and modules that are not related to the entire vehicle; sets a limit for electromagnetic radiation from components to protect on-board receiving devices from interference; classifies automotive components according to the duration of interference and sets a range of limits. Notes
1 Testing of components cannot replace testing of the entire vehicle. The exact relationship between the two depends on the installation location of the components, harness length, harness layout, grounding location and antenna location. However, priority evaluation of components is allowed. 2 Appendix D provides effective solutions to solve interference problems. 206
1 Scope
National Standard of the People's Republic of China
Limits and methods of measurement of radiodisturbance characteristics for the protection of receivers used on board yvehicles
Limits and methods of measurement of radiodisturbance characteristics for the protection of receivers used on board yvehicles Part 1: General
GB 18655---2002
idtIEC/CISPR25:1995
This standard specifies limits and methods of measurement of radiodisturbance characteristics for the protection of receivers used on board yvehicles in the frequency range from 150kHz to 1000MHz. This standard applies to any electronic/electrical component used in vehicles and large installations. The details of the frequency distribution in this standard refer to the International Telecommunication Union (ITU) publications. The limits in this standard are used to protect on-board receivers from disturbances generated by components/modules in the same vehicle2. Part 2 provides the methods and limits for the whole vehicle and Part 3 provides the methods and limits for the components/modules. The types of receivers that need protection are: sound and television receivers, land mobile communications, wireless telephones, amateur and civilian radio equipment. The vehicle in this standard is a self-propelled machine. Vehicles include (but are not limited to) passenger cars, trucks, agricultural tractors and cod land vehicles.
The limits of this standard can be selected by agreement between the automobile manufacturer and the parts supplier. This standard is applicable to automobile manufacturers and automotive electronic and electrical parts suppliers. This standard does not include the protection of electronic control systems from radio frequency (rf) emissions, transient voltages, and pulse voltage fluctuations. These contents are included in ISO publications.
Because the installation location, body structure and wiring harness design will affect Part 3 of this standard defines various limit levels to prevent coupling of radio disturbances to on-board receivers. The limit levels used (as a function of frequency band) are subject to unanimous agreement between vehicle manufacturers and component suppliers. In 1979, the World Regulatory Radiocommunication Conference (WARC) lowered the low-frequency limit for Region 1 to 148.5kHz. For vehicles, a 150kHz test is sufficient. In this standard, the test frequency range has covered radio service frequencies around the world. It is expected that in most cases, radio reception at adjacent frequencies can be protected. It is inferred that if the limits for service frequencies above 30MHz are complied with, protection is likely to be provided for service frequencies below 30MHz.
2 Cited standards
The clauses contained in the following standards constitute the clauses of this standard through reference in this standard. When this standard was published, the versions shown were valid. All standards are subject to revision, and parties adopting this standard should explore the possibility of using the latest versions of the following standards. 1) Only vehicle tests conducted according to vehicle limits can be used to finally evaluate the compatibility of components. 2) It is assumed that adjacent vehicles are protected in most cases. 3) If the level requirements for mobile service frequencies are met, it is considered that appropriate protection is provided for television. Approved by the General Administration of Quality Supervision, Inspection and Quarantine of the People's Republic of China on February 22, 2002 and implemented on March 1, 2003
GB 18655—2002
GB/T4365--1995 Electromagnetic compatibility terminology (IEC60050 (161): 1990) GB14023-2000 Limits and methods of measurement of radio disturbance characteristics of vehicles, motor vessels and devices driven by spark ignition engines (idtCISPR12: 1997)
GB/T6113.1--1995 Specification for radio disturbance and immunity measuring equipment eqvCISPR16-1: 1993) 3 Definitions.
This standard adopts the following definitions:
3.1 Receiver terminal voltage (antenna voltage) receiver terminal voltage (antenna voltage) is the voltage generated by the radio disturbance source, measured by a radio disturbance measuring instrument that complies with the provisions of GB/T6113.1, expressed in dBμV.
3.2 Component continuous conducted emissians are static noise voltages/currents existing in the power lines or other leads of components/modules, which may disturb the receiving ability of the on-board receiver.
3.3 Antenna matching unit Antenna matching unit is an antenna impedance matching unit used to achieve impedance matching with the 502 measurement receiver within the antenna measurement frequency range. 3.4 Antenna correction factor The antenna correction factor is used to convert the voltage obtained at the input end of the measurement receiver into the field strength value measured at the antenna. The antenna correction factor consists of the antenna coefficient and the cable coefficient.
3.5 Compression point When the gain of the measurement system no longer changes linearly at a certain input signal level, the output indication caused by the nonlinearity deviates from the output indication of the ideal linear receiver, and its value is expressed in decibels. 3.6 Class
The execution limit agreed upon by the buyer and seller and recorded in the test plan. 3.7 Device
Non-self-propelled machinery. Devices include, but are not limited to chain saws, irrigation pumps, air compressors, lawn mowers, and fixed or mobile concrete mixers. (See GB14023)
The following definitions are helpful for understanding this standard and are defined in GB/T4365: 3.8 Artificial mains network (line impedance stabiliza-tion network (LISN)) artificial mains network (line impedance stabiliza-tion network (LISN))
A network connected in series at the power supply line of the equipment under test. It provides a specified load impedance for the measurement of the disturbance voltage within a given frequency range and isolates the equipment under test from the power supply. (4.5 of GB/T4365-1995) Note: The abbreviation of artificial mains network is AN.
3.9 Bandwidth bandwidth
3.9.1 (Equipment) Bandwidth bandwidth (of an equipment) The bandwidth of the given characteristic of the equipment or transmission channel deviates from its reference value but does not exceed a certain specified value or ratio. Note: This given characteristic can be an amplitude/frequency characteristic, a phase/dependence characteristic, or a delay/frequency characteristic. (6.9 of GB/T4365-1995) 3.9.2 (of an emission or signal) Bandwidth The bandwidth over which the level of any out-of-band spectral component does not exceed a specified percentage of the reference level. (6.10 of GB/T4365-1995)
3.10 Broadband emission Emissions with a bandwidth greater than the bandwidth of a particular measuring device or receiver. (6.11 of GB/T4365-1995) 3.11 Disturbance suppression Measures to weaken or eliminate electromagnetic disturbances. (3.22 of GB/T43651995) 208
GB 18655--2002
3.12 Disturbance voltage: interference voltage (this name is not recommended) disturbance voltageinterference voltage (deprecated in this sense)
The voltage caused by electromagnetic disturbance between two points on two separated conductors measured under specified conditions. (4.1 of GB/T4365-1995) 3.13 Narrowband emission narrowband emission The emission with a bandwidth less than the bandwidth of a specific measuring device or receiver. (6.13 of GB/T4365-1995) 3.14 Peak detector peakdetector
A detector whose output voltage is the peak value of the applied signal. (4.24 of GB/T4365-1995) 3.15 Quasi-peak detector Quasi-peak detector A detector with a specified electrical time constant, when a regular repetitive equal-amplitude pulse is applied, its output voltage is a fraction of the pulse peak value, and this fraction tends to 1 as the pulse repetition rate increases. (4.21 of GB/T4365-1995) 3.16 Electromagnetic environment Electromagnetic environment The sum of all electromagnetic phenomena present in a given place. (1.1 of GB/T4365-1995) 3.17 Shielded enclosure; screened room A mesh or thin sheet metal shell specially designed to isolate the internal and external electromagnetic environments. (4.37 of GB/T4365-1995) 4 General requirements for emission measurements of vehicles and components/modules 4.1 Overall test requirements and test plan
4.1.1 Test plan description
A test plan should be established for each test item. The test plan shall specify the test frequency range, radiated limits, disturbance level classification (broadband, long or short duration, or narrowband), antenna type and placement, test report requirements, supply voltage and other relevant parameters. 4.1.2 Determination of compliance limits
If the type of disturbance is unknown, it shall be determined by test whether the measured radiation is narrowband or broadband so that appropriate limits can be specified in the test plan.
Figure 1 shows the steps for determining compliance limits. 4.1.3 Types of disturbance sources Electromagnetic disturbance sources (used in the test plan) can be divided into three types: a) continuous/long duration broadband and automatic short duration devices; b) manual short duration broadband devices; c) narrowband devices.
Note: For examples, see 4.1.4, 4.1.5 and Table 1. 4.1.4 Examples of broadband disturbance sources
Note: Table 1 is used as an example to help determine the limits in the test plan. Table 1 Classification of broadband disturbance sources by duration
Continuous
Ignition system
Active driving controller
Fuel injection
Instrument regulator
Alternator
*Defined in the test plan.
"Long-duration"
Wiper motor
Warm windshield motor
Rear wiper motor
Air conditioning compressor
Engine cooling
Short-duration
Electric antenna
Washing pump motor
Door mirror motor
Central control door lock
Electric seat
Measure the EUT with an average detector of the same bandwidth as the peak detector
Determined as narrowband
Failed
GB 18655—2002
Is the difference between the peak value and the average value greater than 6 dB?
Redesign and measure
Use a peak detector to measure the EUT
Is the data below the narrowband
limit?
Confirm it is broadband (If necessary, remeasure with quasi-peak detection)
Is the broadband excitation data below the wideband
limit?
Figure 1 Compliance determination method for radiated/conducted disturbances 4.1.5 Narrowband disturbance sources
From microprocessors, digital logic Interference caused by narrowband radiation such as editors, oscillators or clock signal generators. Yes
4.1.6 Operating conditions
When testing components/modules, the equipment under test (EUT) should simulate the actual installation and operating environment and be tested under typical loads and working conditions.
4.1.7 Test report
The report should include the contents agreed upon by the customer and supplier. 4.2 Measuring equipment requirements
Before the test, all measuring equipment should be calibrated on a fixed reference to ensure consistency when measuring the measuring equipment during the test. Measurement The background noise of the equipment shall be at least 6dB lower than the limit specified in the test plan. 4.3 Shielded room
GB18655—2002
In each test, the ambient electromagnetic noise level shall be at least 6dB lower than the limit specified in the test plan. The shielding effectiveness of the shielded room shall be sufficient to ensure that the requirements for the ambient electromagnetic noise level are met. Note: Although there is energy reflection on the surface of the shielded room, the effect on the conducted disturbance measurement is small because the measuring instrument and the EUT wires are directly coupled. The shielded room can be as simple as a well-grounded shielded room on the test table. The shielded chamber should be of sufficient size to ensure that the vehicle, EUT and measurement antenna are: a) more than 2m away from the wall or ceiling;
b) more than 1m away from the surface of the absorbing material. 4.4 Shielded room with absorbing material (ALSE) For radiated emission measurements, reflected energy can cause an error of more than 20dB. Therefore, it is necessary to use RF absorbing materials on the walls and ceiling of the shielded room to ensure the measurement of radiated emission. Absorbing materials are not required on the ground. When making RF radiated emission measurements, the ALSE must meet the following requirements:
4.4.1 Reflection characteristics
The reflection characteristics of ALSE should satisfy the requirement that the maximum error caused by the energy reflected from the wall and ceiling is less than 6dB in the frequency range of 70 MHz to 1000 MHz.
4.4.2 Objects in ALSE
Specially, all items not related to the radiated emission measurement should be removed from ALSE. This is conducive to reducing the impact on the measurement. These include unnecessary equipment, cable racks, storage cabinets, tables, chairs, etc. Personnel not related to the test should leave the ALSE site. 4.5 Receiver
The measuring instrument should comply with the requirements of GB/T6113.1, and both manual and automatic frequency scanning modes can be used. Special consideration should be given to characteristics such as overload, linearity, selectivity and response to pulses. Note: Spectrum analyzers and scanning receivers are particularly suitable for interference measurement. For the same bandwidth, the peak values ​​displayed by the peak detector mode of the spectrum analyzer and scanning receiver are greater than the quasi-peak value. Since the peak detection scans faster than the quasi-peak detection, it is more convenient to use peak detection for emission measurement. When using quasi-peak limits, a peak detector may also be used for measurement in order to improve efficiency. When any measured peak value equals or exceeds the corresponding single sampling type test limit, the quasi-peak detector shall be used for re-measurement. 4.5.1 Minimum scanning time
The scanning rate of the spectrum analyzer or scanning receiver shall be adjusted according to the frequency band and detection method used. The minimum scanning time/frequency (i.e. the fastest scanning rate) is listed in Table 2:
Table 2 Minimum scanning time
Frequency band 1)
9 kHz~150 kHz
0. 15MHz ~ 30 MHz
30 MHz～1 000 MHz
1) Frequency band definition is in accordance with GB/T6113.1.
Undefined
100 ms/MHz
Peak detection
1 ms/100 ms/MHz2)
2) When using 9kHz bandwidth, use a 100ms/MHz sweep time. Undefined
200 s/MHz
20 s/MHz
Quasi-peak detection
Note: Some signals (such as low repetition rate signals) may require a slower sweep rate or multiple sweeps to ensure the maximum amplitude is measured. For the measurement of pure broadband radiation, the sweep step size is allowed to be larger than the measurement bandwidth in order to increase the measurement speed of the radiation spectrum. 4.5.2 Measuring instrument bandwidth
The bandwidth of the measuring instrument should be selected so that the instrument's background noise value is at least 6dB lower than the limit. The bandwidths in Table 3 are recommended. Note: When the bandwidth of the measuring instrument is larger than the bandwidth of the narrowband signal, the measured signal amplitude will not be affected. When the bandwidth of the measuring instrument is reduced, the indicated value of the broadband impulse noise will decrease.
0. 15 MHz~30 MHz
30 MHz~1 000 MHz
FM broadcasting
Mobile service
GB 18655-2002
Table 3 Measuring instrument bandwidth (6dB)
Broadband peak or quasi-peak
120kHz
120kHz
Narrowband peak or average
120kHz
If the spectrum analyzer is used for peak measurement, its video bandwidth should be at least 3 times the resolution bandwidth. When distinguishing between narrowband and broadband according to Figure 1, the bandwidths of the two (using peak and average detection) should be exactly the same. 5 Antenna and impedance matching requirements Vehicle test
5.1 Antenna type
When the vehicle-mounted antenna is used as a measuring antenna, its installation position and placement style shall be determined according to the product manual. If the vehicle is not equipped with an antenna (which is often the case for mobile communication systems), the antenna types provided in Table 4 can be used for testing. The antenna type and installation position shall be specified in the test plan. Table 4 Antenna type
Frequency band"
SW~AM
VHF~FM
Mobile service (MHz)
70~87
144~172
420~~512
800~1 000
I\LW: long wave; MW: medium wave, SW short wave; VHF: very high frequency. 5.2 Measurement system requirements
5.2.1 Broadcasting band
1m monopole antenna
1m monopole antenna
1m monopole antenna
1m monopole antenna
Antenna type
Loaded 1/4 wavelength monopole antenna
1/4 wavelength monopole antenna
1/4 wavelength monopole antenna
1/4 wavelength monopole antenna
For each frequency band, the measurement must be carried out using an instrument with the following specified characteristics. 5.2.1.1 AM broadcasting
Long wave (150kHz～300kHz)
Medium wave (0. 53 MHz~~2. 0 MHz)
Shortwave (5.9 MHz~6.2 MHz)
The measurement system should have the following characteristics:
The output impedance of the impedance matching unit: 500, Gain: The gain (or attenuation) accuracy of the measurement equipment should reach ±0.5dB. As shown in Figure 2, in each frequency band, the gain of the equipment is limited to a height of 6 dB envelope. The measuring equipment can be calibrated according to Appendix A; Compression point: 1dB compression point occurs when the sinusoidal voltage level is greater than 60dBμV. · Measurement system noise floor: The noise floor of the combined equipment including the measuring instrument, matching amplifier, and preamplifier (if used) is at least 6dB lower than the limit.
Dynamic range: from the noise floor to the 1dB compression point. Input impedance: The impedance of the measuring system at the input of the matching network is at least 10 times the open-circuit 212
impedance of the artificial antenna network specified in Appendix A.
5.2.1.2 FM broadcasting (87MHz～108MHz) GB 18655—2002
Measure with a measuring instrument with an input impedance of 50Ω. If the standing wave ratio (SWR) is greater than 2:1, an input matching network should be used. Any gain or attenuation of the matching unit should be properly corrected. 6dB
Envelope
Figure 2 Gain curve example
5.2.2 Communication frequency band (30MHz~~1000MHz) fuigh
In the frequency range of 30MHz~1000MHz Within the range, the measurement process uses a measuring instrument with an input impedance of 50α and a large line with an impedance of 50Ω.
If the measuring instrument and antenna impedance are different, the corresponding network and appropriate correction factors shall be used. 6 Test equipment for component/module testing only 6.1 Power supply
The EUT power supply shall have an appropriate regulation rate to keep the power supply voltage within the specified limits: unless otherwise specified in the test plan; otherwise, the 12V system shall be 13.5±0.5V and the 24V system shall be 27±1.0V. The power supply shall be appropriately filtered so that the RF noise in the power supply is at least 6dB lower than the limit specified in the test plan. 6.2 Battery
When specified in the test plan, the vehicle battery shall be connected in parallel to the power supply. 6.3 Ground plane
The ground plane used for measuring conducted or radiated emissions shall be a copper plate or galvanized steel plate with a thickness of at least 0.5mm, and its dimensions are shown in Figures 7 to 12.
The ground plane shall be bonded to the shielded room with a DC resistance not exceeding 2.5 m2. In addition, the distance between the bonding plates shall not be greater than 0.9 m. 6.4 Test equipment for conducted emission measurements only 6.4.1 Artificial mains network (AN)
6.4.1.1 AN impedance characteristics
The AN shall have a nominal inductance of 5 μH and conform to the impedance characteristics of Figure 3 with a deviation of ±10%. The circuit diagram in Appendix F is recommended. All AN measurement ports are connected to a 50Ω load (which can be a measuring instrument or a resistor). This allows the AN to be used for measurements up to 108 MHz. bzxz.net
*Although there are several other shortwave broadcast bands, this band is used by most vehicles. Compliance with the limit requirements in this band will protect other shortwave bands.
12)/nt
GB18655-2002
100Frequency/MHz
Figure 35 Impedance characteristics of AN of uH (measured at the EUT end)6.4.1.2 Connection of AN
The emission tests in Chapter 11 and Chapter 13 of this standard shall use the AN specified in 6.4.1.1. When using a TEM cell to conduct the emission test in Article 15, the AN with a coaxial cable connector is easier to connect to the EUT power connector in the TEM cell. 6.4.2 Current probes
The selection of current probes should take into account the following factors: the size of the wiring harness to be measured, the frequency range required by the test plan, and the necessary probe sensitivity to measure the signal at the limit level. Note: A current probe is essentially a transformer that converts current into voltage. Therefore, its correction factor is often called the conversion impedance curve and is given in Q or dBo (see Appendix C).
6.5 Equipment used only for radiated emission measurements of components/modules 6.5.1 Antenna system
Tables 10 and 11 list the limits expressed in dB (μV/m). In theory, any antenna can be used if the antenna has appropriate sensitivity, the antenna correction factor is used, and the antenna provides 502 impedance matching to the measuring receiver. In this standard, the limits shown in Tables 10 and 11 are based on the following antennas.
a) 0.15MHz～30MHz 1m long monopole vertical antenna (a suitable antenna matching unit can be used here, not necessarily 50Q)
b) 30MHz～200MHz a horizontally and vertically polarized biconical antenna; c) 200MHz～1000MHz a horizontally and vertically polarized logarithmic periodic antenna. Commercial antennas with given antenna correction factors (see 3.4) can be used, and the cable loss factor is determined according to Appendix C of GB14023-2000. Note: The method for determining the antenna factor is shown in [1]. 6.5.2 Antenna matching unit
The correct impedance matching between the antenna and the 50Q impedance measurement receiver should be ensured over the full frequency range. The maximum standing wave ratio (SWR) is 2:1. The attenuation or gain of the antenna system (from the antenna to the receiver) should be appropriately corrected. *［1］SAEARP958: December 1992, Electromagnetic Interference Measurement Antennas: Standard Calibration Method; Society of Automotive Engineers, 400-company co-sponsored, approved, PA15096-0001, USA. 214
GB18655-2002
Care should be taken to ensure that the input voltage does not exceed the rated range of the matching unit pulse input to avoid overload. This is particularly important when using active matching units. For details, see Appendix A of this standard.
The biconical antenna can achieve a standing wave ratio of 10:1 in the frequency range of 30MHz to 80MHz, so an additional 2
measurement error will be generated when the receiver input impedance is not 502. If possible, the use of an attenuator (minimum 3 dB) at the receiver input can reduce the additional error. 6.6 TEM cell measurement equipment
6.6.1 TEM cell dimensions
Figure 4 shows an example of a TEM cell. For detailed information on the dimensions and construction of the TEM cell used for component measurements, see Appendix E.
6.6.2 TEM cell test setup (EUT with lead frame) 6.6.2.1 TEM cell
In this test, the partition of the TEM cell functions like a receiving antenna. 1 Outer shield; 2 Partition (internal conductor); 3 Outlet, 4- Connector board, 5- Coaxial connector; 6- EUT 7- Insulating equipment support; 8- Artificial wiring harness Figure 4 TEM cell (example)
6.6.2.2 Power and signal leads
The TEM cell should have a connector board and be as close to the plug connector as possible (see Figure 5). All power and signal leads from the EUT are directly connected to the artificial wiring harness (e.g. lead frame). Unused plugs on the connector board should be sealed to prevent leakage of RF interference. The positive pole of the power line is directly connected to the connector board through AN (see 6.4.1.2). EUT and TEM room floor are not allowed to be directly connected to achieve grounding, and grounding should be achieved through the connector plate.
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