An Electromagnetic-Compliant Scattering Model for Reconfigurable Intelligent Surfaces

This paper presents the development of a novel communication model for reconfigurable intelligent surface (RIS)-assisted wireless systems, utilizing a 2D formulation of electro-magnetic (EM) fields based on Green's theorem. The proposed 2D model is both simple and accurate, adhering to the laws of electromagnetism for the generation, propagation, and scattering of EM fields. Specifically, we establish a direct relationship between the scattered field and the current and impedance of the scattering antenna, resulting in a tractable expression for the total field scattered by the RIS. Moreover, our model successfully explains and analyzes the various diffraction orders present in the scattered field. Through this analysis, we derive an analytical model that predicts and elucidates the different diffraction order components, including the central and replica components. The presented communication model offers valuable insights and predictions for RIS-assisted wireless systems, paving the way for improved system design and performance optimization.