FDTD/GSM Analysis of Multilayered Periodic Structures With Arbitrary Skewed Grid

An efficient algorithm to compute the scattering properties of a multilayered periodic structure with an arbitrary skewed grid using a hybrid finite-difference time-domain/generalized scattering matrix technique is described. In this algorithm, the constant horizontal wavenumber approach for an arbitrary skewed grid is used to compute the scattering parameters of each periodic layer. A complete Floquet harmonic analysis of the periodic structure is presented, where propagation and evanescent behaviors of Floquet harmonics are studied. In addition, guidelines for higher order harmonics selection for certain layers separation is provided. The validity of this algorithm is verified through the good agreement of the numerical results with those obtained from time- and frequency-domain simulations for the entire structure. Furthermore, accurate results for well-known configurations such as frequency selective surfaces with an arbitrary skewed grid under different angles of incidence are obtained. This algorithm yields accurate results with less computational time and memory usage.