Broadband Dual-Polarized High-Selectivity Angular Selective Surfaces Using Polarization-Decoupling Method

This work presents a novel method for designing broadband, highly selective, dual-polarized angular selective surfaces (ASSs). An approach is first introduced for designing broadband TM-polarized ASS, which utilizes the angular dispersion characteristic of the cutoff frequency in the parallel-plate waveguide (PPW). Furthermore, additional short-circuited strips are incorporated between adjacent metal plates to produce angle-dependent transmission zeros (TZs), thus enhancing the angular selectivity. Subsequently, to achieve dual polarization, a polarization-decoupling method is proposed that integrates an ASS valid only for TE polarization into a TM-valid PPW-based structure. The TE-valid ASS functions as a second-order spatial filter, which utilizes the dispersion of dielectric transmission lines (DTLs) to manipulate its angular responses. Finally, the TE- and TM-valid ASSs are co-designed and one dual-polarized ASS is resulted accordingly. The proposed ASS exhibits angular selectivity over a wide frequency band from 6.5 to 9 GHz, with a low profile of $0.65\lambda_{\mathrm {C}}$ (25 mm). For demonstration, one prototype of the dual-polarized ASS is fabricated and measured. The measured results are in good agreement with the simulations.