Analysis of Doubly Periodic Inhomogeneous Dielectric Structures by a Hybrid Projective Method

The problem of plane electromagnetic wave scattering by doubly periodic structures with both homogeneous and inhomogeneous dielectric elements arranged on a homogeneous dielectric substrate is considered. A hybrid projective method involving the method of coupled waves, method of projective matching of fields on the boundaries of partial regions, and one-dimensional finite elements method, is proposed. The method avoids using excessive number of unknown coefficients of expansion taking place in the previous versions. The effectiveness of the method is validated by a few tests including convergence of the results with increasing the number the expansion coefficients and comparison with appropriate data available in literature. The capabilities of homogeneous lossless matching dielectric elements of various shape and some properties of ultra-wideband absorbing structures with pyramidal elements are studied. The potential advantage of using inhomogeneous absorbing elements is also demonstrated.