Design of Multilayer Frequency-Selective Surfaces by Equivalent Circuit Method and Basic Building Blocks

Yuan Xu,Mang He

doi:10.1155/2019/9582564

Abstract

An equivalent circuit method (ECM) is proposed for the design of multilayer frequency-selective surfaces (FSSs). In contrast to the existing ECMs that were developed mainly for the analysis of the properties of a given FSS, the presented ECM aims at providing the initial design parameters of an FSS from the desired frequency response. In this method, four types of basic FSS structures are used as the building blocks to construct the multilayer FSSs, and their surface impedances in both the normal- and the oblique-incidence situations are studied in detail in order to achieve more accurate equivalent circuit (EC) representation of the entire FSS. For a general FSS design with expected frequency response, the EC parameters and the geometrical sizes of the required basic building blocks can be synthesized from a few typical S-parameter (S11/S12) samplings of the response curves via a simple least-square curve-fitting process. The effectiveness and accuracy of the method are shown by the designs of a band-pass FSS with steep falling edge and a miniaturized band-pass FSS with out-of-band absorption. The prototype of one design is fabricated, and the measured frequency response agrees well with the numerical results of the ECM and the full-wave simulations.

Highlights

As a kind of periodic structures, frequency-selective surfaces (FSSs) are widely used as spatial-frequency filters in many applications, such as hybrid radomes, absorbing materials, and electromagnetic shielding devices [1, 2]
As a powerful analysis tool, the equivalent circuit method (ECM) is often utilized to reveal the operation principles of an FSS and to provide an approximate frequency response with acceptable accuracy to the designers [3,4,5], but we can rarely find the FSS designs that are implemented by using the ECM as a design tool according to the required frequency response [6]
We present the results of measurement and give the conclusions in the last section

Summary

Introduction

As a kind of periodic structures, frequency-selective surfaces (FSSs) are widely used as spatial-frequency filters in many applications, such as hybrid radomes, absorbing materials, and electromagnetic shielding devices [1, 2]. The numerical simulations yield accurate frequency response for a given FSS structure, they cannot provide adequate information on how to start an FSS design and how to initialize the geometrical sizes of the design to fulfill the expected frequency response of a general form. As a powerful analysis tool, the equivalent circuit method (ECM) is often utilized to reveal the operation principles of an FSS and to provide an approximate frequency response with acceptable accuracy to the designers [3,4,5], but we can rarely find the FSS designs that are implemented by using the ECM as a design tool according to the required frequency response [6]. Erefore, in principle, these four types of basic structures are good candidates which can be used to construct FSSs with more complicated and required properties Among many FSS designs [3,4,5,6,7,8,9], the FSSs consisting of the strip grid (SG), the square patch (SP), the square slot (SS), and the square loop (SL) elements present excellent HP, LP, BP, and BS performances, respectively, in terms of insensitivity to the polarization and angle of incidence. erefore, in principle, these four types of basic structures are good candidates which can be used to construct FSSs with more complicated and required properties

Objectives

Methods

Findings

Conclusion