Equivalent Circuit Modeling of a Lumped-element Loaded Metasurface under Arbitrary Incidence and Polarization

In this work we develop a simple equivalent circuit model (ECM) that predicts the spectral response of a lumped-element loaded single patterned layer reflective metasurface. The proposed ECM maintains accuracy across varying design parameters including dual-polarization, arbitrary obliquity and azimuthal rotation of incidence plane, as well as physical dimensions of the lumped elements. Our approach is built incrementally, starting from an elementary unit cell which is extended to a 2-by-2 arrangement that allows for multifunctionality and reconfigurability in both polarizations, independently. These capabilities facilitate the design of tunable holographic metasurfaces which can implement reconfigurable intelligent surfaces (RIS) for advanced wireless communication systems. We evaluate the limitations and accuracy of the proposed ECM with full-wave simulations (FWS), which evidence robustness up to 45 degrees and thus highlight its aptitude as a rapid design tool or a guide for FWS-based optimization.