1、 EIA STANDARD TP-66A EMI Shielding Effectiveness Test Procedure for Electrical Connectors EIA-364-66A (Revision of EIA 364-66) May 2000 EIA-364-66A ANSI/EIA-364-66A-2000(R2013) Approved: May 5, 2000 Reaffirmed: January 28, 2013 NOTICE EIA Engineering Standards and Publications are designed to serve
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4、ether the standard is to be used either domestically or internationally. Standards and Publications are adopted by ECIA in accordance with the American National Standards Institute (ANSI) patent policy. By such action, ECIA does not assume any liability to any patent owner, nor does it assume any ob
5、ligation whatever to parties adopting the Standard or Publication. This EIA Standard is considered to have International Standardization implication, but the International Electrotechnical Commission activity has not progressed to the point where a valid comparison between the EIA Standard and the I
6、EC document can be made. This Standard does not purport to address all safety problems associated with its use or all applicable regulatory requirements. It is the responsibility of the user of this Standard to establish appropriate safety and health practices and to determine the applicability of r
7、egulatory limitations before its use. Created under Standards Proposal No. 4730 and reaffirmed under Project No. 5253.01 under the cognizance of the CE-2.0 Committee on EIA National Connector and Socket Standards). Published by: Electronic Components Industry Association 2013 Engineering Department
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9、, contact: IHS 15 Inverness Way East Englewood, CO 80112-5704 or call USA and Canada (1-877-413-5184), International (303-397-7956) i CONTENTS Clause Page 1 Introduction . 1 1.1 Scope . 1 1.2 Object 1 1.2.1 General 1 1.2.2 Mode-stirred test chamber 1 1.2.3 Measurement of connector Shielding Effectiv
10、eness (SE) 2 1.2.4 Methods of measurements 3 2 Test resources . 4 2.1 Equipment . 4 2.1.1 Test chamber . 4 2.1.2 Input power monitoring 5 2.1.3 VSWR of components and cables . 5 2.1.4 Alternative test equipment configuration . 6 3 Test specimen 8 3.1 Description 8 3.2 Preparation 8 3.2.1 Impedance m
11、atch requirements 8 3.2.2 VSWR measurements . 10 3.2.3 Test specimen installation . 10 4 Test procedure . 10 4.1 Test frequencies 10 4.2 Measurement of power from reference antenna and CUT 11 ii Clause Page 4.3 Discrete tuning, test frequencies of 1 GHz to 2 GHz . 11 4.4 Acquiring test data 12 4.5 C
12、alculation of shielding effectiveness 13 5 Details to be specified . 14 6 Test documentation . 14 Table E.1 Circular connector center conductor diameter E-2 E.2 Rectangular connectors nominal dimensions for strip center conductor E-3 Figures 1 Mode-stirred shielding effectiveness system 4 2 Alternat
13、e test equipment configuration . 7 3 preparation and installation of test/specimen/conduit assembly 9 B.1 Mode-tuner construction . B-3 B.2 Details of collet for mounting tuner shaft to drive motor through wall of test chamber B-3 E.1 Cross sectional view of rectangular test specimen with flat-strip
14、 center conductor E-3 E.2 Rectangular connector/tapered adapter/conduit assembly E-4 Annex A Mode-stirred test chamber and antennas (informative) A-1 B Mode-tuner (informative) . B-1 C Test equipment and ancillary components (informative) . C-1 D Mismatch error corrections (informative) . D-1 E Test
15、 specimen and impedance matching (informative) E-1 F Test system dynamic range (informative) . F-1 G References (informative) G-1 EIA-364-66A Page 1 TEST PROCEDURE No. 66A EMI SHIELDING EFFECTIVENESS TEST PROCEDURE FOR ELECTRICAL CONNECTORS (From EIA Standards Proposal No. 4730, formulated under the
16、 cognizance EIA CE-2.0 Committee on National Connector Standards, and previously published in EIA-364-66.) 1 Introduction 1.1 Scope This standard establishes test methods for the measurement of the EMI shielding effectiveness of electrical connectors over the frequency range of 1.0 GHz to 10.0 GHz u
17、sing the mode-stirred technique. The procedure applies to both circular and rectangular connectors. 1.2 Object 1.2.1 General 1.2.1.1 The mode-stirred method for the measurement of connector shielding effectiveness consists of exposing the Connector Under Test (CUT) and a reference antenna to an elec
18、tromagnetic field and comparing the ratio of the signal levels induced into each unit. 1.2.1.2 The electromagnetic field within the mode-stirred test chamber is continuously perturbed by the operation of a rotating reflective element called a mode-stirrer (or tuner). 1.2.1.3 With the proper size tes
19、t chamber and appropriate antennas, the mode-stirred technique can be used over the frequency range of 200 MHz to 40 GHz. 1.2.2 Mode-stirred test chamber 1.2.2.1 The mode-stirred chamber is a large cavity (in terms of a wavelength) with a high quality factor (Q) whose boundary conditions are continu
20、ously perturbed by a rotating reflective surface (tuner or mode-stirrer) mounted within the chamber. Electromagnetic power is established inside the chamber by means of an input or transmitting antenna; see figure 1. EIA-364-66A Page 2 1.2.2.2 The time-averaged electromagnetic fields within the cham
21、ber are approximately equal in amplitude spatially, and are formed by uniformly distributed plane waves. The field distribution at each point in the chamber is then a composite of randomly polarized plane waves; therefore, the average response for the effective aperture of a receiving antenna (or th
22、e connector under test) placed inside the chamber approaches a value equivalent to a gain of unity. 1), 2)1.2.3 Measurement of connector Shielding Effectiveness (SE) 1.2.3.1 The measurement of SE is based on the comparison of the rf power induced into the CUT on the rf power induced into a reference
23、 antenna; see figure 1. The shielding effectiveness of the CUT (expressed in dB) is then defined as: cutrefPPlog 10 SE (dB) where: Pcut = Power coupled to the connector under test Pref = Power coupled to the reference antenna 1.2.3.2 Both the value of Pcut and Pref are determined statistically as a
24、function of tuner position and are determined for the same net input power applied to the chamber. 1.2.3.3 The leakage to be measured is principally that which enters the connector shells under test at the main point of interface. Leakage at the accessory joints is to be prevented by appropriate fix
25、turing. 1) M. L. Crawford, G. H. Koepke, “Design, Evaluation, and Use of a Reverberation Chamber for Performing Electromagnetic Susceptibility/Vulnerability Measurements,” Technical Note 1092, National Bureau of Standard. 2) M. L. Crawford and J. M. Ladbury, “Mode-Stirred Chamber for Measuring Shiel
26、ding Effectiveness of Cables and Connectors,” IEEE August 1988 International Symposium on Electromagnetic compatibility, Seattle, Washington, pp. 30-36. EIA-364-66A Page 3 1.2.4 Methods of measurements There are two basic methods of operating the mode-tune while performing the measurement of the out
27、put levels from the reference antenna and the CUT: discrete tuning: step positioning of the mode-tuner, continuous tuning: constant rotation of the mode-tuner. NOTE It shall be acceptable to use either the discrete-tuned or the continuous tuned method in the measurement of connector shielding effect
28、iveness as described in this test procedure. 1.2.4.1 Discrete tuning 1.2.3.1.1 Discrete tuning provides the optimum accuracy at test frequencies less than or equal to 2 GHz. The mode-tuner is incremented in discrete steps of 1.8 degrees (200 steps) for one full revolution of the tuner, and measureme
29、nts are performed at each tuner position. 1.2.4.1.2 This method permits the measurement of the net input power supplied to the transmitting antenna, the power from the reference antenna and the power from the CUT at each tuner position. Corrections can then be made to normalize the reference antenna
30、 and CUT received power measurements for an equivalent constant net input power as needed to correct for changes in the transmitting antennas input impedance as a function of tuner position. 1.2.4.1.3 This technique also allows corrections to be made for impedance mismatch between the CUT, the refer
31、ence antenna and the power measuring instrumentation as described in annex D. 1.2.4.2 Continuous tuning 1.2.4.2.1 At test frequencies above 2 GHz, the changes in the VSWR of the input antenna vs. tuner position are less significant than at the lower frequencies. This results in improved stability of
32、 the net input power to the test chamber, and enables measurements to be made using continuous stepping (or slow rotation) of the mode-turner position with a minimum of error. 1.2.4.2.2 The output signal levels from the reference antenna and the CUT are measured continuously at a data rate that is v
33、ery fast in comparison to the rate of rotation of the mode-tuner. The large amount of data acquired results in improved measurement accuracy. EIA-364-66A Page 4 Figure 1 Mode stirred shielding effectiveness measurement system 2 Test resources 2.1 Equipment The essential test equipment and components
34、 required for an automated mode-stirred shielding effectiveness measurement system are shown in figure 1. The desired performance criteria for each primary item are summarized in annex C. 2.1.1 Test chamber 2.1.1.1 Mode-stirred shielded enclosure 2.1.1.1.1 Details of recommended test chamber design
35、and construction are given in annex A, together with a description of the mode-tuner and the ridged horn antennas. 2.1.1.1.2 The minimum of any chamber internal dimension shall be greater than three wavelengths at the lowest test frequency. For optimum chamber performance at the lower frequencies, t
36、he volume of the chamber should be as large (with respect to a wavelength) as possible. The ratio of the squares of the chambers linear dimensions should be as non-rational as possible. 1)The test chamber is described further in annex A. EIA-364-66A Page 5 2.1.1.1.3 The chamber should have a shieldi
37、ng effectiveness of at least 100 dB as measured by MIL-STD-285. This level of shielding will enable the measurement of CUT shielding effectiveness levels of greater than 100 dB. As a minimum, the test chamber and the test instrumentation shall have a combined shielding effectiveness at each test fre
38、quency that is 10 dB greater than the minimum shielding requirements of the CUT. 2.1.1.2 Mode-tuner The mode-tuner should be large with respect to a wavelength and be bent at angles to the walls of the chamber. The tuner should be at least two wavelengths from tip to tip at the lowest test frequency
39、. The mode-tuner is further described in annex B. 2.1.1.3 Antennas The input and reference horn antennas should be placed in different corners of the chamber and located so that they face into the corners. This orientation will minimize possible direct-path coupling from the input antenna to the ref
40、erence antenna or to the CUT. The preferred relative placement of the antennas and the CUT within the test chamber are shown in figure 1. 2.1.2 Input power monitoring The incident-signal power meter, see figure 1, is used to monitor the level and stability of the incident power to the input antenna.
41、 The reflected power meter enables the determination of the new input power to the chamber. 2.1.3 VSWR of components and cables 2.1.3.1 The individual components of the measurement system should be of good quality, with an input and output VSWR of 1.3:1 or less. This applies especially to all compon
42、ents, cables, and instrumentation in the signal paths from both the reference antenna and the CUT assembly. This precaution will minimize the magnitude of mismatch uncertainties, and facilitate measurement error analysis; see annex D for further discussion on corrections for mismatch errors. EIA-364
43、-66A Page 6 2.1.3.2 The range of mismatch uncertainty in dB can be found from the following: Maximum mismatch loss = -10 log 1 - ( |S| + |L|)2 (dB) Minimum mismatch loss = -10 log 1 - ( |S| - |L|)2 (dB) where: S = Reflection coefficient of the source (reference antenna or CUT) L = Reflection coeffic
44、ient of the load (detector or receiver/spectrum analyzer) The magnitudes, | S | and | L | can be obtained from the appropriate VSWR by the equation: 1VSWR1VSWRi where: i = S or L 2.1.3.3 Cable and component losses Characterize all cables, attenuators, directional couplers, and switches for VSWR and
45、attenuation (or coupling factor) at each test frequency prior to beginning the test. 2.1.3.3.1 This data will be used to correct the measurement system readings of reference antenna and CUT output levels, and if desired, the input power to the test chamber. These corrections can be made part of the
46、test program for an automated mode-stirred system. NOTE All individual data that is to be averaged later should be stored in units of power (milliwatts), not in dBm or other measurement units. EIA-364-66A Page 7 2.1.4 Alternative test equipment configuration 2.1.4.1 The method used in figure 1 to mo
47、nitor the signal level from the reference antenna provides several advantages. The use of the calibrated attenuator/diode detector assembly enables simultaneous monitoring of both the reference and the CUT signals, reducing errors due to any drift in the rf source power level and decreases the requi
48、red test time by one half. 2.1.4.2 The use of a switched input to the receiver/spectrum analyzer to enable monitoring the outputs of first the reference antenna, and then the CUT, may be used in lieu of a separate monitoring channel. This alternative test system configuration is shown in figure 2. N
49、OTE The coaxial switch configuration used to switch between the reference antenna and the CUT shall provide a 50 ohm termination to the unused signal channel. The maximum crosstalk between inputs should be at least 10 dB greater than the difference between the two test signal levels. Figure 2 Alternate test equipment configuration EIA-364-66A Page 8 2.1.4.3 The use of the receiver/spectrum analyzer for the measurement of both the reference antenna and the CUT channels places added importance on the amplitude stability of the rf p
