Reduced-order modeling of multiscreen frequency-selective surfaces using Krylov-based rational interpolation

A method is presented for generating a broad-band rational interpolant approximation of the reflection coefficient of multiple-screen frequency-selective surfaces (FSSs). The technique is structured around a linearization of the system provided by a spectral domain moment method-based analysis of the FSS, followed by a model-order reduction of the linearized system using the dual rational Arnoldi method. This process creates a rational interpolant of the linearized system that matches its transfer function and its derivatives at several expansion points in the Laplace domain. Numerical results indicate that a reduced-order model with a system matrix of dimension less than 20/spl times/20 can accurately reproduce the broad-band behavior of multiscreen FSSs originally modeled with several hundreds or thousands of unknowns.