Ultra-wideband metamaterial absorber using three-layer ring and patch resonators

This paper proposes a three-layer ultra-wideband metamaterial absorber, which consists of layered ring resonators and four rectangular patch resonators on the top. The structure is rotationally symmetrical and hence becomes polarization-insensitive. This absorber realizes an absorption bandwidth of 22.39 GHz within 6.37-28.76 GHz for absorptivity level above 90%. The overall thickness of this absorber is 4.9mm, which is only 0.10X and 0.21X at the lowest and highest frequencies, respectively. The proposed structure exhibits wider absorption bandwidth in comparison with the state of arts.