Method of Moments Simulation of Infinitely Periodic Structures Combining Metal With Connected Dielectric Objects

A method of moments (MoM) technique is described for the simulation of infinitely periodic structures made of complex elements, involving both metal and dielectric parts. A numerical approach based on the MoM was developed, using the EFIE formulation for metallic objects and a modified PMCHWT formulation for the air-dielectric interfaces. The method is also based on an efficient algorithm for the computation of the singly and doubly periodic Green's functions and their gradients. The use of such functions for both inside and outside problems enables the analysis of. structures where the dielectric volumes of successive cells are connected. The accuracy of the MoM approach is assessed in several cases, based on energy conservation checks and on comparisons with analytical models and data available in the literature. Examples are shown for arrays of disconnected and connected dielectric objects, dielectric electromagnetic band-gap (EBG) superstrates and dielectric slabs. Examples with metallic parts embedded in connected dielectric material are given in the case of frequency selective surfaces (FSS) and tapered-slot antennas.