A broadband multilayer circuit analog absorber using resistive ink

Abstract

In this article, a polarization-insensitive broadband multilayer circuit analog absorber has been designed and demonstrated. The proposed structure is comprised of two layers, each layer being made of resistive square loop geometries printed on low-cost FR4 substrates. The substrates are separated from each other by an air spacer and the overall geometry is terminated by a ground plane. By proper design optimization, the structure exhibits a wide absorption bandwidth (having absorptivity above 90%) from 2.68 to 15.90 GHz, covering S, C, X, and Ku frequency bands. A fractional bandwidth of 142.30% has been achieved from the proposed geometry, at the expense of moderate thickness (0.086 λl, λl being the wavelength corresponding to the lowest absorption frequency). Further, the topology is polarization-independent and angularly stable for different polarizations. An in-depth analysis has also been carried out by developing an equivalent circuit model and illustrating several parametric variations. One prototype has been fabricated and measured under normal incidence, thereby validating the proposed concept. © 2020 Wiley Periodicals LLC