Efficient analysis of metasurfaces in a planar layered medium

Gaussian ring basis functions (GRBFs) are proposed for the method of moments (MoM) analysis of metasurfaces (MTSs) in a planar layered medium. We solve the relevant integral equation for the homogenized problem, accounting for the MTS layers as impedance boundary conditions. The closed-form spectra of the GRBFs allows an efficient computation of the MoM impedance matrix using the spectral-domain approach and asymptotic expansions. Moreover, these basis functions represent the global evolution of the surface current density in an effective manner, which leads to a significant reduction of the number of unknowns.