Design of a polarization-insensitive triple-band metamaterial absorber

A polarization-insensitive triple-band metamaterial absorber (MMA) is proposed in this paper. It is composed of three-layer structure: metal-dielectric-metal. The top metal layer is consisted of two close ring resonators. The outer is a square ring resonator and the inner is a circular ring resonator, the two ring resonators have a common center. A commercial software CST Microwave Studio (CST MWS) is used to investigate the MMA. The simulation result shows that the MMA has three absorption peaks at 3.70 GHz, 6.57 GHz and 17.62 GHz, with absorption rate of 99.67%, 99.05% and 99.98%, respectively. The electric field, magnetic field and surface current distribution of the MMA are given to study its absorption mechanism. The polarization-insensitivity of the absorber is also analyzed. Moreover, the effects of line width and thickness of dielectric layer on absorption are discussed. Because of its excellent absorption performance and simple structure, the triple-band MMA has potential applications in many fields, such as radar stealth, thermal radiometer, spectral imaging and so on.