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1、_ _ _ _ _ _ _ STD-IEEE L302-ENGL 1738 W 4805702 0559454 8bL IEEE Std 1302-1 998 IEEE Guide for the Electromagnetic Characterization of Conductive Gaskets in the Frequency Range of DC to 18 GHz IEEE Electromagnetic Compatibility Society Sponsored by the Standards Committee W W w I Rtbkbe by the Insti
2、tUte of EectkaIand Elecmnics Enginmrs, Inc, 3 4 5 East 47th Street, New Y (978) 750-8400. Permission to photocopy portions of any individual standard for educational class- room use can also be obtained through the Copyright Clearance Center. Copyright The Institute of Electrical and Electronics Eng
3、ineers, Inc. Provided by IHS under license with IEEELicensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/25/2007 03:29:01 MDTNo reproduction or networking permitted without license from IHS -,-,- STD-IEEE 1302-ENGL Introduction 1998 rn Li805702 0559457 570 rn (This introduction is not p
4、art of IEEE Std 1302-1998, IEEE Guide for the Electromagnetic Characterization of Conduc- tive Gaskets in the Frequency Range of DC to 18 GHz.) An electromagnetic interference (EMI) gasket is a conductive material that is used to improve the electrical bonding between metallic parts of an electronic
5、 chassis, equipment enclosure, or electromagnetic shield. A wide variety of materials and techniques are used to produce EM1 gaskets. The effectiveness of gaskets in the closing of seams and joints is dependent upon the properties of the gasket and the method of installation. Several techniques are
6、available to measure the electromagnetic properties of EM1 gaskets. Unfortunately, measurement results are often inconsistent between techniques. This document provides guidance on the use of recognized techniques for the electromagnetic performance characterization of EM1 gaskets. It does not recom
7、mend one technique over another. It is recognized that some or all of the “alternative” techniques may, at some time in the future, become widely accepted and practiced. At that time, this guide will be revised to reflect their adoption. It is also recognized that efforts are currently underway to r
8、evise the measurement techniques currently covered in this guide. These revi- sions will be included in future updates of this guide. The theory of gasket behavior given in this guide is highly simplified, and is intended to illustrate primary principles only. For a greater understanding of the elec
9、tromagnetic interactions that occur in a gasketed joint, the reader is advised to consult the many excellent mathematical treatments in books and papers avail- able through the IEEE and other technical publishers. Participants The following persons were members of the P1302 Working Group and contrib
10、uted to the preparation of this guide: Dale Ashby Dwayne R. Awerkamp Robert Benn Ronald W. Brewer Joseph E. Butler, Jr. David Castro Hafeez Choudhary Gary Fenical Richard T. Ford Gustav J. Freyer Hugh W. Denny, Chair Bob Gibson Mark Hansen Michael O. Hatfield William Hoge Robert Johnk D. Mark Johnso
11、n Galen Koepke George M. Kunkel Phillip Lessner The following persons were on the balloting committee: Dale Ashby Dwayne R. Awerkamp Stephen H. Berger Ronald W. Brewer Edwin L. Bronaugh Joseph E. Butler, Jr. Hugh W. Denny Franz Gisin David A. Graham Donald N. Heirman Lothar O. Hoeft Daniel D. Hoolih
12、an Motohisa Kanda John G. Kraemer George M. Kunkel William McGinnis Michael K. McInerney Dheena Moongilan Robert Mulhall John D. Osburn Jose Perini John P. Quine Michael McInerney Bob Mulhall Steve Mullenix W. Drew Peregrim John P. Quine T. J. Ritenour Robert A. Rothenberg Joseph Rowan Michael Taylo
13、r David A. Weston T. J. Ritenour Robert A. Rothenberg Joseph Rowan Risaburo Sato Michael J. Scougall Ralph M. Showers Ronald T. Stickney Dale Svetanoff Donald L. Sweeney David L. Traver David A. Weston Copyright O 1998 IEEE. All rights resewed. . 111 Copyright The Institute of Electrical and Electro
14、nics Engineers, Inc. Provided by IHS under license with IEEELicensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/25/2007 03:29:01 MDTNo reproduction or networking permitted without license from IHS -,-,- STD*IEEE L302-ENGL 1998 = Li805702 0559458 Li07 The final conditions for approval o
15、f this standard were met on 20 May 1998, This standard was condition- ally approved by the IEEE Standards Board on 19 March 1998, with the following membership: Richard J. Hollernan, Chair Donald N. Heirman, Vice Chair Judith Gorman, Secretary iv Satish K. Aggarwal Clyde R. Camp James T. Carlo Gary
16、R. Engmann Harold E. Epstein Jay Forster* Thomas F. Garrity Ruben D. Ganon James H. Gurney Jim D. Isaak Lowell G. Johnson Robert Kennelly E. G. “Al” Kiener Joseph L. Koepfinger* Stephen R. Lambert Jim Logothetis Donald C. Loughry L. Bruce McClung Louis-Franois Pau Ronald C. Petersen Gerald H. Peters
17、on John B. Posey Gary S. Robinson Hans E. Weinrich Donald W. Zipse *Member Emeritus i 1 Copyright O 1998 IEEE. All rights reserved. Copyright The Institute of Electrical and Electronics Engineers, Inc. Provided by IHS under license with IEEELicensee=NASA Technical Standards 1/9972545001 Not for Resa
18、le, 04/25/2007 03:29:01 MDTNo reproduction or networking permitted without license from IHS -,-,- i Contents 1 . 2 . 3 . 4 . 5 . 6 . 7 . 8 . 9 . 10 . Overview 1 1.1 Background 1 1.2 Scope 2 1.3 Purpose . 2 References 2 Definitions. acronyms. and abbreviations 3 3.1 Definitions . 3 3.2 Acronyms and a
19、bbreviations . 3 Factors affecting gasket performance 4 Electromagnetic behavior of gasketed joints . 6 Gasket measurement techniques 11 6.1 Transfer impedance 13 6.2 Relative aperture transmission . 15 6.3 Alternative techniques . 20 Selecting a gasket measurement technique 25 7.1 Measurement refer
20、ence 7.2 Sample configuration 26 7.3 Frequency range . 26 7.4 Dynamic range . . 27 7.5 Other considerations . . 27 Repeatability 28 Measurement uncertainty . 29 Bibliography 29 Copyright O 1998 IEEE . All rights reserved . V Copyright The Institute of Electrical and Electronics Engineers, Inc. Provi
21、ded by IHS under license with IEEELicensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/25/2007 03:29:01 MDTNo reproduction or networking permitted without license from IHS -,-,- STD-IEEE L302-ENGL 1998 m 4805702 05594b0 Ob5 m IEEE Guide for the Electromagnetic Characterization of Conduc
22、tive Gaskets in the Frequency Range of DC to 18 GHz 1. Overview 1.1 Background The ideal electromagnetic shield is an infinitely conductive enclosure with no apertures or penetrations of any kind. The functional requirements and practicalities of design and construction, however, prevent this ideal
23、from being realized. Penetrations for power, signals, and ventilation must be provided. Access aper- tures for calibrations, controls, and adjustments must exist. The different pieces of chassis and enclosure must be joined for the final product. Electromagnetic energy exits or enters the shield at
24、apertures, along conductive penetrations, and through imperfect seams. To restrict this coupling of energy to levels that are sufficiently low to comply with regula- tions and to permit interference-free operation, these unwanted coupling paths must be closed. Filters are used on the penetrations; s
25、creens and covers may be used over the apertures. Seams and joints, however, require special attention. For shielding, metal-flow processes such as welding, brazing, and soldering are the preferred methods for m a k i n g joints and seams. Many situations arise, however, in which these techniques ca
26、nnot be used, and in which direct metal-to-metal contact does not provide an adequate electromagnetic seal. In these cases, an electromagnetic interference (EMI) gasket must be installed in the joint. EM1 gaskets are conductive materials that are designed to conform to joint surfaces and to provide
27、a low- impedance path. EM1 gaskets are made from a wide variety of materials, such as beryllium copper, galva- nized steel, stainless steel, electroplated steel, aluminum, and conductively loaded polymers. Conductor types include spring fingers, spiraled bands, perforated sheets, knitted wire mesh,
28、conductive fabric, rein- forced foil, and oriented wires. Materials added to polymeric binders to achieve conductivity include copper, silver, carbon, aluminum, and nickel as flakes, powders, wires, and coated spheres. The shapes available include sheets, strips, washers, tubes, and customized geome
29、tries. The term “EM1 gasket” is consistent with the generic industrial definition of a gasket. The electromagnetic fields that are being shielded impinge upon the conductive materials of the enclosure. The incident field induces currents in the enclosure walls. Seams represent discontinuities in shi
30、eld current paths, with result- Copyright O 1998 IEEE. All rights reserved. 1 Copyright The Institute of Electrical and Electronics Engineers, Inc. Provided by IHS under license with IEEELicensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/25/2007 03:29:01 MDTNo reproduction or networki
31、ng permitted without license from IHS -,-,- STD-IEEE 1302-ENGL 2778 = Li1905702 0557LibL TT1 W IEEE Std 1302-1 998 IEEE GUIDE FOR THE ELECTROMAGNETIC CHARACTERIZATION OF CONDUCTIVE ing voltage differentials across the seams. The purpose of the EM1 gasket is to reduce the voltage differential across
32、the seam because the strength of the field emanating from the seam is directly proportional to this voltage. Depending upon function and application, electronic equipment must operate in an extremely wide range, in both intensity and frequency, of electromagnetic environments. The environments can v
33、ary from that of the home to that of the battlefield. Since there is no “one sizehype fits all” gasket, the challenge that faces equip- ment designers is that of choosing the most cost-effective gasket for their particular application. An essential parameter in this selection process is the degree t
34、o which the gasket prevents the electromag- netic energy that impinges on one side of the metal joint containing the gasket from coupling through the joint to the other side (Le., the gaskets electromagnetic sealing capability). Many factors determine the elec- tromagnetic seal provided by an EM1 ga
35、sket, including a) The gasket material b) The gasket construction c) d) e) The method of fastening f) The closure pressure g) The geometry of the joint The condition of the contact surfaces The nature of the impinging field The ideal EM1 gasket measurement technique would reveal the full range of ef
36、fects caused by mounting sur- face variations, aging, and fasteners, and would provide results that indicate the behavior that is expected from the gasket as installed. Currently, no single measurement technique does this over the frequency range of dc to 18 GHz. 1.2 Scope This guide provides guidan
37、ce on the selection of the best technique for measuring EM1 gaskets for particular applications, identifies limitations and sources of errors of the commonly accepted techniques for measuring gaskets, and provides a basis for comparing the various accepted techniques. It encompasses measurements of
38、the as-installed behavior of gaskets as well as manufacturing related, quality-control measurements. 1.3 Purpose The purpose of this guide is to provide information that will allow the user of conductive gaskets to select the best measurement technique for a given application and to correctly interp
39、ret the data that is provided by each technique. 2. References This guide shall be used in conjunction with the following standards. A bibliography is included in Clause 10 for further information. ANSVNCSL 2540- 1- 1994, Calibration-Calibration Laboratories and Measuring and Test Equipment- General
40、 Requirements. i ANSI publications are available from the Sales Department, American National Standards Institute, 11 West 42nd Street. 13th Floor, New York, NY 10036, USA. 2 Copyright O 1998 IEEE. All rights reserved. Copyright The Institute of Electrical and Electronics Engineers, Inc. Provided by
41、 IHS under license with IEEELicensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/25/2007 03:29:01 MDTNo reproduction or networking permitted without license from IHS -,-,- STD-IEEE 1302-ENGL 1998 m ii1105702 05594b2 938 m I GASKETS IN THE FREQUENCY RANGE OF DC TO 18 GHz IEEE Std 1302-1
42、998 ARP 1173-1988 (Reaff 1991), Test Procedure to Measure the RF shielding Characteristics of EM1 Gaskets.* ARP 1705-1981 (Reaff 1991), Coaxial Test Procedure to Measure the RF Shielding Characteristics of EM1 Gasket Materials. ASTM D4935-89 (1994), Standard Test Method for Measuring the Electromagn
43、etic Shielding Effectiveness of Planar material. Def Stan 59-103 (17-Sep-93), EMVEMP Gasket component. IEEE Std 100-1996, IEEE Standard Dictionary of Electrical and Electronics Terms5 IEEE Std 299- 1997, IEEE Standard for Measuring the Effectiveness of Electromagnetic Shielding Enclo- sures. MIL-G-8
44、3528B (1993), General Specifications for Gasketing Material, Conductive, Shielding Gasket, Elec- tronic, Elastomer, EMI/RFL6 NCSL RP- 12 (4/95), Recommended Practice for Determination and Reporting of Measurement Uncertain- ties. 7 3. Definitions, acronyms, and abbreviations 3.1 Definitions All term
45、s used in this document are in accordance with IEEE Std 100-1996. 3.2 Acronyms and abbreviations ARP dB pV/m dBpA/m EME EM1 MSC SAE SE TEM aerospace recommended practice decibels above a microvolt per meter decibels above a microampere per meter electromagnetic environments electromagnetic interfere
46、nce mode-stirred chamber Society of Automotive Engineers shielding effectiveness transverse electromagnetic 2Aerospace Recommended Practices are available from the Society of Automotive Engineers, 400 Commonwealth Drive, Warrendale, PA 15096, USA. 3ASTM publications are available from the American S
47、ociety for Testing and Materials, 100 Barr Harbor Drive, West Conshohocken, 4Defence Standards may be obtained from the Ministry of Defence, Directorate of Standardization, Kentigem House, 65 Brown Street, Glasgow, Scotland, G2 SEX. IEEE publications are available from the Institute of Electrical an
48、d Electronics Engineers, 445 H o e s Lane, P.O. Box 1331, Piscataway, MIL publications are available from Customer Service, Defense Printing Service, 700 Robbins Ave., Bldg. 4D, Philadelphia, 7NCSL publications can be obtained from the National Conference of Standards Laboratories, 1800 30th Street,
49、 Suite 305B. Boulder, PA 19428-2959, USA. N J 08855-1331, USA. PA 1911 1-5094, USA. CO 80301-1032, USA. Copyright O 1998 IEEE. All rights reserved. 3 Copyright The Institute of Electrical and Electronics Engineers, Inc. Provided by IHS under license with IEEELicensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/25/2007 0