Circuit Modelling and Analysis of Multiband Energy-Selective Surfaces Using Characteristic Modes

This work presents a novel circuit modelling approach for predicting and analyzing the scattering parameters of energy-selective surface (ESS). The proposed circuit model is derived from the theory of characteristic modes, whose solution provides the resonant properties (eigenvalues) and the associated characteristic fields (eigenvectors). The orthogonality of the eigenvectors permits the derivation of a Forster-like Type-II canonical circuit. Full-wave simulations performed on several structures validate the accuracy of the proposed circuit modelling. This provides a useful analytical tool for deriving the scattering properties in the initial design process. In addition, the eigen-solutions provide more field information to support the nonlinear response analysis. As a proof-of-concept, the final ESS design shows triband adaptive protection against high power microwave. It is confirmed that the proposed approach is expected to provide benefits for multiband ESS design.