A Novel Band-Reject Frequency Selective Surface With Pseudo-Elliptic Response

A novel frequency selective surface (FSS) exhibiting pseudo-elliptic band-reject response is presented. The proposed FSS consists of a two-dimensional periodic array of microstrip lines. For an incident wave of linear polarization perpendicular to the printed lines, virtual magnetic walls are formed between the microstrip lines. Since a microstrip line shielded with magnetic side walls supports two quasi-TEM modes, the two-dimensional array effectively forms a dual-mode resonator. The elliptic response is thus realized by coupling the incident wave to both modes of the resonator. A wideband pseudo-elliptic response is achieved by including higher-order modes of the array. To analyze this FSS, we treat it as a cascaded junction of air-to-microstrip line discontinuities, and investigate the problem using the full-wave mode-matching method. We provide useful design guidelines for both narrow-band and wide-band FSSs, while explaining the effect of various geometrical parameters on the performance of this FSS. Narrow-band and wideband FSS prototypes are fabricated and measured results validate our design concept. This new class of FSS is easy-to-assemble, exhibits a superior performance, and is thus potentially useful for many practical applications.