A Polarization-insensitive Metamaterial Absorber with both Low and High Frequency Absorption Based on Magnetic Material

Abstract

In this article, a polarization-insensitive metamaterial absorber with both low and high frequency absorption based on magnetic material has been presented. The proposed absorber consists of metal pattern and metallic ground plane, which separated by magnetic material dug a square hole. Through digging a square hole inside the magnetic material, the absorption performance of magnetic material in the high frequency band is broadened, while the low frequency absorption is realized through the periodic metal pattern. It is verified by simulation that the absorber can achieve a strong resonance absorption near 1.47GHz and high absorptivity above 85% from 4.4GHz to 15GHz in the case of normal incidence. In order to explain the mechanism of high absorption, the power loss at the resonance frequencies are investigated. The magnetic field distributions of the four structures (magnetic material, magnetic material with square hole, magnetic material with periodic metal pattern and the proposed absorber) were compared to explain the widening of the high frequency bandwidth by digging hole. Furthermore, the total thickness of our structure is 2mm, which is approximately $1/ 102 \lambda$ at 1.47GHz. Due to the symmetry of the absorber, it is insensitive for the polarization. Therefore, the proposed absorber can provide a new possibility and idea in spanning both low and high frequency bands.