Analysis and Design of Ultra Thin Electromagnetic Absorbers Comprising Resistively Loaded High Impedance Surfaces

TL;DR

This paper presents the design and analysis of ultra-thin electromagnetic absorbers using resistively loaded high impedance surfaces, achieving wideband absorption through a circuital model and experimental validation.

Contribution

It introduces a novel resistive patterning method for high impedance surfaces to create wideband absorbers without extensive lumped resistors.

Findings

Optimal surface resistance depends on substrate parameters and FSS shape.

Circuit model effectively predicts absorber impedance and bandwidth.

Experimental results confirm wideband absorption performance.

Abstract

High-Impedance Surfaces (HIS) comprising lossy Frequency Selective Surfaces (FSS) are employed to design thin electromagnetic absorbers. The structure, despite its typical resonant behavior, is able to perform a very wideband absorption in a reduced thickness. Losses in the frequency selective surface are introduced by printing the periodic pattern through resistive inks and hence avoiding the typical soldering of a large number of lumped resistors. The effect of the surface resistance of the FSS and dielectric substrate characteristics on the input impedance of the absorber is discussed by means of a circuital model. It is shown that the optimum value of surface resistance is affected both by substrate parameters (thickness and permittivity) and by FSS element shape. The equivalent circuit model is then used to introduce the working principles of the narrowband and the wideband absorbing structure and to derive the best-suited element for wideband absorption. Finally, the experimental validation of the presented structures is presented.