A Macroscopic Ray-based Model for Reflective Metasurfaces

Reconfigurable Intelligent Surfaces (RISs) have gained significant attention in research studies focused on their technology and/or potential applications. While several modeling approaches have been proposed - ranging from analytical integral formulations to simplified approaches based on scattering matrix theory there is still a great need for efficient and electromagnetically-consistent macroscopic models that can simulate scattering from RISs, especially for the purpose of large-scale simulations purposes. In the present paper we propose a fully ray-based approach, based on the characterization of the RIS through a "spatial modulation" function that can be easily embedded in efficient, forward ray tracing models. We validate the proposed model by comparison to well established methods available in the literature and show that, although the considered method is completely different and more efficient, results are as accurate if not indistinguishable in a typical benchmark case.