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.