Wideband metasurface absorber (metabsorber) using characteristic mode analysis

Abstract

Designing an ultra-wideband metasurface absorber is challenging because of its lossy characteristic that hinders the understanding of its resonance behavior. In this study, a framework was formulated to extend the application of the theory of characteristic modes to the analysis and design of metabsorbers. The metabsorber and its lossless counterpart exhibited similar modal behaviors, hence revealing the absorption mechanism of metabsorber. By introducing absorption modes, a dual-band metabsorber was converted into an ultra-wideband metabsorber. This proposed metabsorber with a thickness of 1.99 times the Rozanov's limit could measure a bandwidth of 5.51-36.56 GHz (or 6 octaves) with 90% absorptance.