Engineering Spatial Dispersion to Synthesize Arbitrary Spatial Filters Based on Metagratings

Abstract: This paper presents a design framework for synthesizing angularly selective spatial filters using non-uniform metagratings. While traditional metagratings focus on channeling energy into higher-order Floquet modes for a fixed incidence angle, we leverage the fundamental mode as a versatile degree of freedom to engineer spatial dispersion over a continuous angular spectrum. By strategically distributing non-uniformly loaded metallic wires and rigorously modeling their mutual interactions through an impedance-matrix formulation, we realize prescribed angular transfer functions with high efficiency. In particular, the framework is validated at 3.5 GHz through full-wave simulations of (i) low-pass, (ii) high-pass, and (iii) all-pass spatial filters. The results demonstrate that fundamental-mode engineering in non-uniform metagratins offers a highly efficient platform for advanced spatial wave manipulation.