Circuit Modeling for Frequency-Selective Surfaces Using Characteristic Modes

This work presents a novel methodology for equivalent circuit modeling and analysis of arbitrarily shaped frequency-selective surfaces (FSS). The proposed equivalent circuit model (ECM) is derived from characteristic current expansion of surface induced currents. The orthogonality of the eigen-solutions permits to obtain Forster-like II-type circuits with frequency-independent components, and the resulting circuits accurately reproduce the resonant response of the FSS structure over a wide frequency band. In addition, an FSS consisting of bent metal strips with rotationally symmetric is proposed for multi-band electromagnetic shielding. Good agreement between ECM and full-wave simulation.