Efficient Green's function formulation for analysis of frequency selective surfaces in stratified media

The most time consuming part of analyzing an arbitrarily shaped frequency selective surface (FSS) in a stratified medium using the method of moments is filling the generalized impedance matrix. The prime contributor to matrix fill time is repeated numerical evaluation of the periodic Green's functions. This issue has been dealt with in the past by seeking efficient numerical schemes for evaluating the Green's functions (see Singh, S. et al., 1990; Shubair, R.M. and Chow,Y.L., 1992), or by interpolating the impedance matrix over frequency (see Barlevy, A.S. and Rahmat-Samii, Y., 1997). We report an efficient wide-band formulation of the potential Green's functions that allows the most time consuming calculations to be performed just once per phasing, for any number of analysis frequencies. A dramatic reduction in execution time is obtained.