Numerical analysis of scattering fields by a multiple plane grating using shadow theory

Abstract

In the shadow theory, a new description of electromagnetic fields using scattering factors has been employed. This paper presents a new numerical method based on scattering factors for the scattering problem of a composite dielectric grating embedded with conducting strips. The scattering factors for the primary fields, which are based on the assumption of conducting strips being removed completely and those for the secondary fields generated by the surface electric currents on conducting strips, are introduced. The presented method is formulated to obtain scattering factors for the total fields and Joule losses for propagating wave and evanescent wave incidences from the currents determined by using the Galerkin procedure. Numerical examples are given for an asymmetric multiple plane grating consisting of conducting strips. The scattering properties and the normalized Joule losses are calculated for propagating wave and evanescent wave incidences. It is shown that the diffraction efficiencies and scattering factors hold the symmetries on the reciprocity in the case of resistive plane gratings.