Spectral FDTD: a novel computational technique for the analysis of periodic structures

The finite-difference time-domain (FDTD) technique is a robust analysis tool in electromagnetics. Recently, periodic structures, in which a periodicity exists in one or more of their dimensions, have been given special attention. In the analysis of periodic structures by FDTD, implementation becomes difficult for a plane wave at oblique incidence. The paper presents a novel technique, referred to as spectral FDTD, for the analysis of a plane wave incident on 2D periodic ground planes. Each simulation by the spectral FDTD gives the reflection coefficient for a fixed value of wavenumber over a wide range of frequencies. The technique provides stable results for grazing incidence, where most algorithms fail.