Synthesis of second-order wide-passband frequency selective surface using double-periodic structures

Abstract

A new second-order wide-bandpass frequency-selective surface (FSS) composed of a two-dimensional periodic array cascading aperture-type FSS and strip-type FSS with different periods is proposed and investigated. The cascading structure of two parallel electric sheets is systematically analysed based on boundary conditions formulated in terms of surface impedances. By retrieving equivalent circuits of each cell, the operating principle of the proposed FSS can be qualitatively analysed and discussed. The synthesised FSS can provide not only the wide passband characteristics but also transmission zero at the adjacent resonant frequency. A sample of the square loop array is designed and measured. Good agreement between equivalent circuit analysis, simulation, and measurement results is obtained. The suggested FSS is shown to be a simple structure with a stable wide bandpass response under different incident angles.