Design of Closely Spaced Tri-band and Dual-polarized Bandstop FSS in C-band

In this paper, a tri-band bandstop frequency selective surface (FSS) with closely spaced characteristics operating in the C-band(4-8GHz) is proposed. The FSS is designed as a single-layer structure consisting primarily of an FR-4 substrate and a metal layer. It can be utilized as a bandstop filter for applications in the C-band. The resonant frequencies of the three bandstop are 4.56 GHz, 6.42 GHz, and 7.41 GHz, and this structure has a minimum band ratio (BR) of only 1.15. The advantage of this structure lies in its ability to provide excellent triple-band response while maintaining a small BR. Additionally, it exhibits a stable response for both TE and TM polarizations across a wide range of incident angles. The effectiveness of the proposed method is confirmed through rigorous validation using the CST Studio Suite.