Analysis of singly and doubly periodic absorbers by frequency-domain finite-difference method

In this paper, the theory and numerical algorithms of a periodic finite-difference frequency domain (PFDFD) method are presented for the analysis of arbitrarily shaped inhomogeneously filled, singly and doubly periodic absorbers. The PFDFD method is based on a finite-difference solution of the Maxwell´s curl equations plus an absorbing boundary condition, metallic backing, and Floquet´s periodic condition to define the problem in a finite region. Compared to the integral equation (IE) and moment method techniques, the PFDFD algorithm is simpler to develop, more efficient to model electrically large geometries, and more flexible to analyze absorbers with both electric and magnetic loadings. The theory and algorithms proposed in the paper have been validated via numerous examples and agree very well with those of other techniques and measurements