Wideband Simulations of Periodic Structures by the Hybrid Spectral FDTD/TD-VFz Method

The spectral finite-difference time-domain method is combined with the discrete-time time-domain vector fitting (TD-VFz) algorithm to analyze three-dimensional (3-D) periodic structures excited by oblique incident plane waves over a wide frequency band. The time signal reconstruction with TD-VFz produces an untruncated response over an infinite time window allowing an accurate spectral result, especially near the cutoff frequency separating the spectrum propagating wave region of the evanescent wave region.