Bandpass FSS With Zeros Adjustable Quasi-Elliptic Response

In this letter, a frequency selective surface (FSS) with quasi-elliptical bandpass filtering response and high-frequency selectivity is proposed. The structure consists of two arrays, i.e., a hollow metal pipe array and a metal disk array printed on a thin substrate layer. The FSS exhibits a flat transmission in the passband and fast roll-off. By investigating the electric fields and using equivalent circuit models, physical insights into the generation of the transmission/reflection zeros and operating principle of the whole FSS are obtained. The positions of the transmission zeros can be independently changed by adjusting the corresponding parameters that tune the bandwidth of the passband. A prototype is fabricated and measured to verify the simulation.