Dual-Band X-Shaped Absorber Design for Sensor Applications

Abstract

This study presents a compact absorber design with an X-shaped resonator (XSR) in the S-band region. The proposed design offers single or dual-band absorption peaks, depending on whether the arm lengths of the resonator are symmetrical or asymmetrical. Prototype fabrications of the absorber, whose numerical design was carried out using CST Microwave Studio, were also measured for verification. Based on the simulated and measured results, the proposed absorber exhibited over 93% absorption spectra with relatively narrow bandwidth characteristics desired, especially for sensor applications. It also provided cross-polarized reflections of less than 0.08 at the frequencies of interest. In addition, the absorption frequency changes depending on the dielectric constant and thickness variations of the sensing layer placed on the absorber were obtained numerically and experimentally to investigate the sensing performance of a dual-band configuration of the absorber. In addition, the same analyzes and measurements were carried out again for two separate single-band split-ring resonator (SRR)-based absorbers designed in this study, and their sensing performances were compared with the dual-band X-shaped absorber's performance. As a result, it was found that the proposed X-shape absorber was more sensitive than the SRR-based absorber, considering the comparison results.