A rigorous cell-network model for computing the transmission & scattering properties of finite frequency selective surfaces

The problem of time harmonic electromagnetic scattering from, and transmission through, finite frequency selective surfaces (FSSs) has been formulated by an extension of the equivalence principle. The basic equivalence situation for three regions (the FSS plus two exterior regions) is extended in the FSS region to a cell level. The FSS is assumed to be constructed of a two-dimensional array of contiguous cells, each of which is identical. A network representation is constructed, via the method of moments, for each region in terms of admittance matrices. Complete characterization of the FSS region involves only the admittance matrix of a single cell, which, in general, is much smaller than the FSS. The cell admittance is calculated by the finite element method using tetrahedral edge elements. The exterior and cavity admittance matrices are dense and use integral equation formulations. This approach results in a significant reduction in the computer time required to accurately characterize the FSS region, which can also consist of inhomogeneous and anisotropic materials.