Fast Numerical Analysis of Metasurfaces by Characteristic Basis Functions in EFIE Framework

Metasurface (MTS)-based reconfigurable intelligent surfaces (RISs) are able to actively control the reflection and refraction patterns on a surface to create a programmable and reconfigurable wireless propagation environment. A fast electric field integral equation (EFIE) formulation is developed here to model MTS-field interactions for RISs. The novelty of the formulation is that it utilizes characteristic basis functions (CBFs) designed specifically for approximating surface current densities on MTSs, thereby significantly reducing the necessary number of unknowns and decreasing the solution time compared with employing the standard Method of Moments technique with Rao-Wilton-Glisson (RWG) surface basis functions. In this work, we validate the novel numerical technique and demonstrate the substantial improvement in numerical performance utilizing a 2-D illustrative structure.