IEEE 1302: “Guide for the Electromagnetic Characterization of Conductive Gaskets in the Frequency Range of DC to 40 GHz”
Gasketing can be critical to achieving EMC success. Imagining a metal enclosure with a removable lid, that lid may not seat perfectly around the entire perimeter. There are plenty of reasons for this: number of fasteners, bowing of the material, gaps for other purposes, etc. EMI gaskets are conductive materials meant to seat in that perimeter and make contact with both the lid and the enclosure body, filling in potential gaps. There are about a million different kinds of gaskets, from conductive elastomers to beryllium copper fingerstock. Likewise, there are a lot of different ways to characterize how effective they are. No single method is perfect, so IEEE 1302 exists to provide descriptions of accepted standard test methods and guidance on which test to choose for a given application. IEEE 1302 can be purchased here.
Here are the main test methods discussed in IEEE 1302:
Transfer impedance based on SAE ARP 1705 (2006, Rev A)
Transfer impedance based on SAE ARP 1705 (2017, Rev C)
Relative aperture transmission based on MIL-STD-285 and/or IEEE 299, including SAE ARP 1173, MIL-DTL-83528G, and DefStan 59-103
Stripline method, per SAE ARP 6248 (2016)
Effective transmission aperture using total radiated power through a gasketed aperture
Slot aperture, modifying MIL-DTL-83528G to use a 3 mm x 500 mm slot instead of a 610 mm x 610 mm square to mount the gasketing material
Nested reverb chambers
Far-field TEM-t fixture, analogous to ASTM D4935-1989
Near-field H-t fixture, similar to TEM-t but measuring magnetic shielding performance
DC resistance measurement as a very basic check
In Table A.1 the document evaluates each test method on the following parameters:
Measurement principle/field condition
Parameter measured
Unit of measure
Size of measuring fixture
Test sample configuration
Sample size (minimum length needed)
Visual control on mechanical behaviour
Real mechanical construction details
Environmental and corrosion tests (salt fog/humidity)
Frequency range
Dynamic range
Repeatability
Measurement uncertainty
Remarks on SE value
The following paper by the chair and vice-chair also has detailed information of what went into the 2019 revision of the standard (which was originally published in 2008): J. Catrysse and D. Pissoort, "IEEE Std. P1302–2019: A Guidance Document for the Characterization of Shielding Gaskets," in IEEE Letters on Electromagnetic Compatibility Practice and Applications, vol. 2, no. 3, pp. 67-71, Sept. 2020, doi: 10.1109/LEMCPA.2020.3017349.