High-Order Resonance in a Multiband Metamaterial Absorber

Abstract

The typical metamaterial absorber includes a single absorption band, based on a single resonator. We note that four or more absorption peaks are formed by only a single meta-atom, that is, a widely used cut-wire (CW) structure. Through a differential equivalent-circuit approach, the absorption mechanism of odd-order magnetic resonance and electric resonance in CW was elucidated by one unique circuit. With electrical interaction between adjacent meta-atoms taken into consideration, the absorption properties of a CW structure are proved as a function of the geometric parameters, and are verified through numerical and experimental results. By obtaining the experimental results of disk-structured meta-atoms showing higher than third-order magnetic resonance absorption bands, the existence and absorption properties of higher-order magnetic resonances for meta-atoms in a non-CW metamaterial are shown to be coherent with those of a CW structure. This presence of multiple absorption peaks opens the possibility for multiband metamaterial absorbers not only in the GHz but also in the visible range.