A Low-Profile Dual-Polarization Frequency Selective Surface Based on Stacked Patches

In this work, a low-profile third-order dual-polarized frequency selective surface (FSS) with a transmission zero is proposed. The FSS consists of three patch layers and a ground plane. The mixed electromagnetic coupling between the top two patch layers introduces a transmission zero at the passband edge. The top two patch layers are coupled to the bottom patch resonator via cross-shaped apertures. An equivalent circuit incorporating mixed electromagnetic coupling has been developed. By slotting the patches, the strength of either electric or magnetic coupling can be adjusted. The proposed FSS operates within the frequency range of 4.6 GHz to 5.0 GHz, featuring a fractional bandwidth of 8.3 % and an insertion loss of approximately 1.3 dB. It exhibits excellent angular stability under both TE and TM polarizations. Additionally, it offers the advantage of a low profile, with a height profile of only <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$0.024 \lambda_{0}$</tex>.