Dual-band ordered and disordered metamaterial absorber

We present dual-band metamaterial absorbers that are composed of concentric metal double rings, a dielectric spacer and a metallic ground plane. The coupling between the top electric resonators and the bottom metal layer leads to a strong magnetic resonance. The metamaterial with ordered double rings has two absorption peaks at frequencies of 5.67 GHz and 11.30 GHz with the absorption rates of 99.8% and 99.5%, respectively. Further, the metamaterial with disordered double rings still exhibits polarization insensitive dual-band absorption with the absorption rate larger than 87.5% for both x- and y-polarized waves. With geometrical scalability, this metamaterial with dual-band absorption may operate at other frequency regimes even THz range, which makes it a good candidate to design a high-performance absorber.