Synthesis Design of Bandpass Frequency-Selective Surface Based on Frequency-Dependent Coupling Structure

In this article, a frequency-dependent coupling (FDC) structure is proposed for the synthesis design of bandpass frequency-selective surface (FSS). The proposed FDC structure consists of two pairs of shorting pins and four loop slots, which can independently control the negative and positive coupling. The coupling characteristics and control of the FDC structure are analyzed in detail. This FDC structure can be used to design FSS with various topologies to realize different transmission zero distributions. In order to verify the effectiveness of the FDC structure, a second-order topology and a cascaded triplet (CT) topology are employed to design the FSSs with different transmission zero distributions, and a detailed procedure for the synthesis design of the FSS is given. Based on the CT topology, one FSS configured with two transmission zeros above the passband is fabricated and measured, which verifies the effectiveness of the proposed coupling structure in the synthesis design of the FSS.