EMI SHIELDING TEST METHOD FOR SMALL WIRELESS DEVICES

摘要

We introduce a new cavity-to-cavity isolation standard for measuring the electric field attenuation of EMI/RFI shielding systems used in small wireless devices. The test specimen, which represents the shielding system under evaluation, is a "ladder box" strip containing three small, isolated, five-sided box compartments. The test sample is placed on a printed-circuit board, which contains a ground trace and an antenna beneath each compartment. The antennae are connected to a network analyzer, which is used to measure the EMI/RFI shielding between cavities. The approach is utilized to compare different materials and methods used for shielding small compartments in wireless devices. The shielding systems comprise of both a substrate and an interface. Various substrates such as metal, metal-coated plastic, painted plastic, and filled conductive plastic are evaluated in conjunction with conductive silicone gaskets.