Ultra-Wideband Metamaterial Absorber Based Electromagnetic Hybrid Loss

In this article, an ultra-wideband low-profile and lightweight metamaterial absorber is proposed. The proposed absorber is composed of three graphene-based lossy layers and a magnetic absorption layer at the bottom. Besides, three foam layers provide support and coupling between different layers. In the lossy layers, ohmic loss is achieved for the incident electromagnetic wave from 2 GHz to 20 GHz by the graphene film. The magnetic absorption layer is placed at the bottom of the structure, which can achieve low-frequency absorption below 1GHz and acts as a reflecting plate for the upper loss layer at 2-20GHz. As a result, the proposed structure exhibits absorption characteristics from 0.6 GHz to 20 GHz (85% absorption from 0.6 GHz to 2.4 GHz, 90% absorption from 2.4 GHz to 10 GHz, 96% absorption from 10 GHz to 20 GHz) with relative bandwidth of 188.3%. Due to the adoption of the bottom magnetic absorption layer, the thickness of the proposed absorber is only 0.044 λl, where λlis the free-space wavelength at the lowest absorption frequency. To explain the absorption mechanism, an analysis of the current and electric field distribution at different operating frequencies is presented. The absorption performance remains stable under different polarizations and oblique incidence.