Rational Krylov reduced order modeling of multiscreen frequency selective surfaces

Multiscreen frequency selective surfaces (FSSs) are useful over a broad part of the electromagnetic spectrum as frequency or angular filters, and they have been especially important as subreflectors in dish antennas. The most popular method for the calculation of the reflection from FSSs due to incident plane wave excitation is the method of moments (MoM). This method results in a system of equations for the weighting coefficients for the basis functions representing the current, and a linear relation between the weighting coefficients and the screen reflection coefficient. Unfortunately, iterating the MoM to calculate the reflection coefficient over a band of frequencies is computationally costly. At each frequency, it involves both the construction and solution of large linear systems. Therefore, the goal of this paper is to construct a reduced order model of the system of equations.