Efficient Analysis of Frequency-Selective Surfaces by a Simple Equivalent-Circuit Model

TLDR

Approximate analysis using a lumped‑LC network provides physical insight into the working principles of frequency‑selective surfaces. The study evaluates the transmission and reflection properties of FSSs using a simple, accurate first‑order circuit approach. The authors compute and store lumped L and C parameters at normal incidence, then derive generalized relations to adapt these parameters for arbitrary dielectric thickness, incident angle, and periodicity, enabling rapid response calculations via an equivalent transmission line model. The simplified model’s predictions agree closely with MoM simulations.

Abstract

The transmission and reflection properties of frequency-selective surfaces (FSSs) are evaluated through a simple and accurate first-order circuit approach. The approximate analysis, based on the parallel between real structure and a lumped-LC-network counterpart, is also useful for acquiring physical insights into the working principles of frequency-selective surfaces. The first part of the paper describes a technique for computing lumped parameters of the most common frequency-selective-surface elements. The L and C parameters representing a given frequency-selective-surface element are derived only one time, at normal incidence, and stored, so as to form a database. The second part of the paper deals with the derivation of simple relations allowing the generalization of the stored LC couples in the case where the frequency-selective surface is printed or embedded in arbitrarily thick dielectric slabs, when the incident angle is varied from normal incidence, or if a different periodicity with respect to the reference periodicity is adopted. The generalized lumped parameters are included in an equivalent transmission line for computing the response of generic frequency-selective-surface configurations with no additional computational effort. The results obtained through the simplified model presented here are verified by a careful comparison with MoM simulations.