Frequency-Selective Surfaces With Quasielliptic Bandpass Response for Filtering FRA Application

This work proposes an asymmetric antenna–filter–antenna (AFA)-based frequency-selective surface (FSS) with quasielliptic bandpass response and polarization selectivity. According to the reciprocity theorem, radiation nulls of antennas can be used to introduce transmission zeros (TZs) of AFA-based FSSs. The proposed FSS consists of two patch antennas with different slots, a ground, and a metalized via connecting two patch antennas. The antenna’s radiation nulls are generated by slots embedded in the patches, which act as a notch band and can be used to modulate the FSS frequency response with two TZs by varying the length of slots. The high-frequency selectivity performance of FSSs can be achieved without additional circuits or multilayer structures. For a potential application, we design a filtering folded reflectarray (FRA) by using the proposed FSS as its subreflectarray. The filtering characteristic of the proposed FRA, with steeper frequency response and flat gain in the passband, can be obtained. A prototype of filtering FRA is fabricated and measured. Good agreement is obtained between simulated and measured results.