Coding Metasurfaces for Diffuse Scattering: Scaling Laws, Bounds, and Suboptimal Design

Coding metasurfaces, based on the combination of two basic unit cells with out‐of‐phase responses, have been the subject of many recent studies aimed at achieving diffuse scattering, with potential applications to diverse fields ranging from radar‐signature control to computational imaging. Here, via a theoretical study of the relevant scaling‐laws, the physical mechanism underlying the scattering‐signature reduction is elucidated, and some absolute and realistic bounds are analytically derived. Moreover, a simple, deterministic suboptimal design strategy is introduced that yields results comparable with those typically obtained by approaches based on brute‐force numerical optimization, at a negligible fraction of their computational burden, thereby paving the way to the design of structures with arbitrarily large electrical size. Results are corroborated by rigorous full‐wave numerical simulations and microwave experiments, and may be of interest in a variety of application fields, such as the design of low‐scattering targets and illumination apertures for computational imaging, not necessarily restricted to electromagnetic scenarios.