IEEE Standard P1302™:
A Guidance Document for the
Characterisation of Shielding Gaskets

On 26 June 1998, the first edition of the standard IEEE Std 1302TM /1998 “IEEE Guide for the Electromagnetic Characterisation of Conductive Gaskets in the Frequency Range of DC to 18 GHz” was published.
Since that time, much has changed in technologies and measuring methods. Related to this background, a new PAR 1302 has been introduced for reviewing and updating the actual version. The first meeting of this PAR 1302 was held during the IEEE EMC Symposium of August 2002 in Minneapolis. A tremendous amount of work has been accomplished; the second edition of this standard is now available.

First Edition of IEEE Std 1302 (1998)
From the beginning, it has been clear that a number of measuring methods were available, used and supported by research work. As some of them were already standardised and other used as “de facto” industrial standards, it has been decided from the beginning to edit a guidance document for good engineering practice instead of producing a “real” standard.
Since the publication of the first edition, some of the mentioned standards became obsolete, or have been replaced by other ones. Other methods are no longer supported by any practical experience or scientific work.
Therefore, a review of the standard was necessary in order to keep it up-to-date and to provide gasket manufacturers and gasket users a valuable guidance document on how to characterise shielding gaskets.

Review Process of IEEE Std 1302 by PAR P1302
The first meeting of the new working group was held during the IEEE EMC Symposium of August 2002 in Minneapolis. Following this meeting, a survey of available and known methods to characterise shielding gaskets was identified and listed. In that sense, a collection of measuring methods was evaluated and ranked for valuable use in order to characterise the shielding by conductive gaskets.
Most of the members of this specific task force of P1302 were representatives of manufacturers of gasket materials. They were very interested to have a set of standardized methods available for the characterisation of shielding gaskets over a broad frequency range.
Following the first meeting of the task force in 2002, all members have been analyzing and discussing the different methods in a critical way, based on their practical needs and experience. Most of the work was done by email discussions, and an annual ‘face-to-face’ meeting during the IEEE EMC Symposia in Boston (2003), Santa Clara (2004), Chicago (2005) and Portland (2006).
During these meetings, critical discussions and fundamental decisions were made. In 2003, all identified methods had been analyzed, and the decision was made on which methods should be maintained in the new document.
In 2004, a first proposal for the structure of the document was discussed and agreed upon. Based on this structure, a first draft was written and circulated for comments and remarks by email, so that it could be discussed in depth during the next IEEE EMC symposium in Chicago.
In 2005, the final structure of the new document was discussed in detail, and the final draft was agreed upon by the working group during the Portland meeting of 2006. This can be seen as the end of the technical part of the work, and the start of the more administrative part of the work effort.
This holds the approval of the draft by the IEEE SA committees and the voting procedure. Approval by voting is done by an ad hoc committee, with representatives from the academic world, manufacturers and end users of gaskets.
Following this open procedure, the standard has been finally approved at the end of 2008, and is now in the final editing phase of publication. It will be available in early 2009.
The new document IEEE Std 1302 will offer guidance for the designer, to make the right choice of test method, and/or to understand the SE values obtained by different methods, as a function of the test conditions applied and the application of use.
As (past) chairman of the taskforce P1302, I want to thank all the people who supported the work by:
• the careful analysis of the proposed methods
• to bring the experience of their companies on the proposed methods to the task force, in an “open discussion forum”
• the critical reading of all drafts during the process of editing the structure and the wording of the new document
Especially, I want to thank the following people for their valuable technical contributions on different measuring methods, their practical implementations and their Pro’s and Con’s: Joe Butler, Gary Fenical, Bill Hoge, Mike Oliver, Bob Welch, George Kunkel, Christian Brull, Mike Hatfield and Tomas Clupper. They all shared their experience from daily practice in open and constructive discussions during the meetings.

Content and Structure of IEEE Std 1302: 2008
The content and structure of the 2nd edition of IEEE Std 1302 will have the following sections:
• Factors affecting gasket performance
• compression rate of the gasket
• mechanical design of the joining section
• type of material of the gasket, and the enclosure to be used
• related type of test fixture and size
• frequency range of application
• environmental conditions (corrosion, vibration)
• field conditions (far field/near field)
• field strength level
Short overview of gasket measuring techniques: a general discussion, including:
• Standardised gasket measuring techniques
• transfer impedance as SAE ARP 1705
• relative aperture transmission, based on some modified versions of the (obsolete) MIL-STD-285, 285 (or IEEE 299), MIL-G-83528 B, ARP 1773 and Def Stan 59-103
• Alternative techniques, derived from standards
• effective transmission aperture
• slot aperture
• (nested) reverberation chambers
• Alternative non-standard based methods
• far field TEM-t
• near field H-t
• DC resistance measurement
• A discussion on how to select a measuring technique as a function of the type of gasket and its intended application. A table summarizing all characteristics of each method is included to help the user in choosing the right methodology.
It is followed by a set of annexes that discuss in more depth the measuring techniques and a list of references.
The new document IEEE Std 1302 offers a guidance for the designer to make the right choice of a test method, and/or to understand the SE values obtained by different methods, as a function of the test conditions applied and the application of use.

Future Work
The actual status of the P1302 standard “IEEE Guide for the Electromagnetic Characterization of Conductive Gaskets in the Frequency Range of DC to 18 GHz” has been presented.
As technology is moving into higher clock frequencies in electronic applications, higher carrier frequencies for wireless communication systems and new microwave applications (ex. anti-collision radar in automotive applications) that will be introduced, an extension of the frequency range will be needed in the near future.
In parallel with this evolution, it is observed that very thin gaskets are used in special applications, such as gaskets used to preserve the shielding of on board shielding at the PCB level. Another type of emerging technology is the so called “molded in place” gasket.
For both the range of higher frequencies, and the very thin gasket applications, appropriate measuring methodologies must be developed and validated. The scientific part of the work is going on in some research laboratories, but standardisation will be needed in the near future.
In that perspective, extending the IEEE Std. 1302 into a higher frequency range – up to 40 GHz – and providing adopted test methodologies for very thin gaskets, must be the work program of a new task force IEEE P1302-1. This work could be started during 2009 in close contact with similar work being done on small shielded enclosures by the task force IEEE P299-1.
If you are interested in the work to be done under IEEE P1302-1, defining methods for the characterisation of very thin gaskets up to the frequency range of 40 GHz, please contact Prof. Johan Catrysse, EMC


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