Estimation of Effectiveness of EMI Gaskets by using Results of Standardized Measurements

Abstract

A technique for evaluating the effectiveness of the use of EMI gaskets is proposed. These conductive gaskets are designed to protect against electromagnetic interference and installed, for example, at the joints of metal sheets and in the slots of doorways of shielded rooms. The technique makes it possible to calculate the in-situ shielding effectiveness of an EMI gasket by using the standardized shielding effectiveness of this gasket (which is taken from the datasheet of the gasket or measured in accordance with applicable standards) and the geometrical characteristics of the places of gasket mounting (i.e., shape and size of the slot). The technique is validated by comparing the calculated and measured values of the shielding effectiveness in a wide frequency range (from 800 MHz to 18 GHz) for various types of the EMI gaskets (finger-spring gaskets, wire-mesh gaskets, conductive cloth pads) placed in slots of various sizes and shapes (straight, curved).