Equivalent circuit method for analysis and synthesis of frequency selective surfaces

A new general equivalent circuit approach for a thin frequency selective structure (FSS) has been proposed. The method exhibits higher accuracy compared with conventional equivalent circuit approaches, is valid for any angle of incidence and for any lattices, provides a better understanding of how a particular FSS structure operates and potentially allows the synthesis of FSS by optimisation of circuit parameters. In addition its performance is much faster than techniques employing rigorous solutions. A theoretical study of the method has been undertaken using ring slot and rectangular slot elements as test elements for the analysis. Very good agreement in comparison with computational electromagnetics (CEM) software and rigorous methods has been obtained.