Time harmonic and transient scattering by finite periodic flat strip arrays: hybrid (ray)-(Floquet mode)-(MOM) algorithm

A frequency and short-pulse (SP) time-domain (TD) study of two-dimensional plane wave scattering from a finite periodic array of thin, flat, coplanar perfectly conducting strips is presented. Rigorous analytical-numerical reference solutions are established by spatial spectral wave number decomposition and the method of moments (MOM), followed by frequency inversion. The analytical portion is approximated so as to yield via high-frequency asymptotics, for a sufficiently large number of strips, a hybrid ray-Floquet-mode-MOM algorithm that not only explains the phenomena in physical terms but is also numerically efficient and reasonably accurate when compared with the reference solution. Of special interest are the TD Floquet modes with their space-time-dependent frequencies and wave numbers. By superposition, they can synthesize the highly resolved pulse train return under SP conditions. Attention is given also to direct SP-TD synthesis, and to processing options for SP-TD data