Volume integral equation for analysis of dielectric periodic structures

The space-domain volume integral equation (VIE) method is presented for the analysis of three-dimension (3-D) scattering from dielectric frequency selective structures (DFSS). The method solves directly for the electric field in order to easily enable periodic boundary conditions in the spatial domain. The computation of the spatial domain periodic Green´s function (PGF) is accelerated by the modified Ewald transformation, so that very thick periodic structure can also be analyzed efficiently and accurately. The free-space PGF is very smooth and amenable to interpolation. Thus, optimized interpolation procedures for the PGFs can be applied, resulting in a considerable reduction of matrix-filling time without any significant effect on the accuracy. A study of the scattering parameters of a multilayered dielectric periodic structure is accomplished by imposing the boundary conditions in terms of the multimode scattering matrix. Numerical examples show the reliability and accuracy of the proposed method.