Hybrid Technique for the Analysis of Scattering from Periodic Structures Composed of Irregular Objects

In the paper, the analysis of electromagnetic wave scattering from multilayered frequency selective surfaces is presented. The surface is composed of periodically arranged posts with irregular shapes. The multimodal scattering matrix of such structure is derived and the transmission and reflection characteristic for the structure with arbitrary plane wave illumination are calculated. The exact full-wave theory based on the hybrid approach employing mode-matching method and finite-difference frequency-domain (FDFD) technique is applied to develop an efficient theory to analyze such structures. The validity and accuracy of the approach are verified by comparing the results with those obtained from alternative methods and own measurements of manufactured periodic structures.