Frequency Selective Surfaces for Electromagnetic Shielding of Pocket-Sized Transceivers

Abstract

This article presents a comprehensive study of the use of small-sized frequency selective surfaces (FSS) to selectively shield pocket-sized devices against EM disturbances. A typical use case is to protect a 2.4-GHz transceiver (e.g. WiFi/Bluetooth) against ISM/GSM disturbances (around 868/915 MHz), using an 8.2 × 4.1 cm FSS structure. A detailed comparison is drawn between results in real and emulated far-fields for different FSS-to-antenna distances (5 and 25 mm), which is further confirmed by emission measurements employing an open transverse electromagnetic cell. Results demonstrate, in line with full-wave simulations including calculated Poynting integrals, that such a FSS can effectively reduce power by about 5 dB in the stopband, while providing no attenuation in the passband and is small enough for an easy integration. Moreover, it is shown that the farther the FSS from the antenna, the closer the results to a no-FSS scenario. This provides an insight to reconsider FSSs for the shielding of mobile and/or smart devices.