A Joint Analysis of Frequency-Selective Surfaces at Oblique Incidence in the Frequency, Angular, and Polarization Domains

This article presents a comprehensive analysis of frequency-selective surfaces (FSSs) under oblique incidence, covering the frequency, angular, and polarization domains through their equivalent circuit models (ECMs). The FSS structure is modeled as a microwave network, and its normalized impedance characteristics across these domains are systematically derived. The analysis addresses the conditions for perfect transmission, perfect reflection, and transmission bandwidth in the angular domain. To validate the proposed methodology, a dielectric slab with specifically tailored electrical and physical parameters is studied. Theoretical calculations and numerical simulations demonstrate diverse angular and frequency responses, including single-polarized single-pole filters, single-polarized multipole filters, double-polarized single-pole filters, and all-pass filters. Furthermore, detailed procedures for deriving the equivalent circuits and analyzing multilayer slabs, air layers, and metal-loaded structures are provided to extend the method’s applicability. A prototype slab is fabricated, and measured results show excellent agreement with theoretical predictions and numerical simulations, confirming the validity and effectiveness of the proposed approach.