Engineering of Absorbing Gaskets Between Metal Plates

Engineering of absorbing materials for gaskets that would be used between two metal plates to reduce electromagnetic emissions and improve immunity of electronic equipment is considered. An analytical model of a composite based on the Maxwell Garnett formulation for multiphase mixtures, as well as the shielding effectiveness of this material, are presented. The full-wave numerical computational results for the structure consisting of two overlapping metal plates and an engineered gasket composite material in the place of the overlap are presented.

I. Introduction

Conductive or absorbing gaskets are frequently used in the gaps between the metal plates to reduce emissions, and improve the immunity of electronic equipment. Any slot in an enclosure constructed of highly-conductive materials, may play the part of an unintentional antenna, if surface current lines cross this slot. The problem is to eliminate slots as well as possible surface currents that are culprits of undesirable emission. Conductive gaskets are typically used between the conductive plates of an enclosure, for example, around door frames of an electronic block. However, conductive gaskets do not always ensure perfect electrical contact between the plates. This can lead to a discontinuity of surface currents, resulting in unwanted electromagnetic coupling and emissions.