Nonuniform metasurface analysis in FDTD Based on Susceptibility GSTCs

An accelerated analysis method for non-uniform metasurfaces in FDTD is presented for the first time. The non-uniform metasurfaces are modeled by a distribution of susceptibilities, homogenized parameters. Those susceptibilities are calculated from scattering coefficients of each elements based on Generalized Sheet Transition Conditions (GSTCs). Next, susceptibility modeled metasurface is simulated in 3D FDTD in a form of surface polarization currents. For simplicity, this paper only consider frequencies well below resonance, where the susceptibility is an approximate constant.