On the Bandwidth of High-Impedance Frequency Selective Surfaces

TL;DR

This paper analyzes the bandwidth of high-impedance surfaces using an improved equivalent circuit model that includes the series inductance of the FSS, providing clearer design guidelines for maximizing bandwidth.

Contribution

It introduces a more accurate equivalent circuit model for HIS by incorporating FSS series inductance, enhancing bandwidth estimation and design.

Findings

Including FSS series inductance improves bandwidth prediction.

Reducing FSS inductance leads to wider bandwidth.

Explicit bandwidth expression aids in optimal HIS design.

Abstract

In this letter, the bandwidth of high-impedance surfaces (HISs) is discussed by an equivalent circuit approach. Even if these surfaces have been employed for almost 10 years, it is sometimes unclear how to choose the shape of the frequency selective surface (FSS) on the top of the grounded slab in order to achieve the largest possible bandwidth. Here, we will show that the conventional approach describing the HIS as a parallel connection between the inductance given by the grounded dielectric substrate and the capacitance of the FSS may induce inaccurate results in the determination of the operating bandwidth of the structure. Indeed, in order to derive a more complete model and to provide a more accurate estimate of the operating bandwidth, it is also necessary to introduce the series inductance of the FSS.We will present the explicit expression for defining the bandwidth of a HIS, and we will show that the reduction of the FSS inductance results in the best choice for achieving wide operating bandwidth in correspondence with a given frequency.