Accelerated 3-D Analysis of Metasurfaces for RIS Applications by Characteristic Cell Functions

A fast 3-D numerical solver based on an electric field integral equation (EFIE) formulation is developed for analyzing metasurfaces (MTSs) in reconfigurable intelligent surface (RIS) applications. As part of the numerical model, a new methodology is introduced for the systematic generation of characteristic cell functions (CCFs). The CCFs provide a global approximation function set for the surface currents on perfect electric conductor (PEC) patches of the MTS cells with significantly fewer unknowns than regular localized expansion functions. In this work, we demonstrate the feasibility of CCFs for 3-D illustrative scenarios and present the substantial performance improvement they enable.