Perfect absorber with separated ‘dielectric–metal–ground’ metamaterial structure

Abstract

Abstract A metamaterial perfect absorber whose effective thickness is less than 1/1000 of the operating wavelength is proposed. Different from the traditional ‘metal–dielectric–ground’ type metamaterial absorber, it adopts a novel ‘dielectric–metal–ground’ structure, and the ‘dielectric–metal’ structure is separated from the ‘ground’. Through this design, the effective thickness of the absorber is reduced to about 1/2200 of the wavelength. This will make the absorber suitable for imaging and sensing applications. Next, a bi-material cantilever absorber based on the proposed structure is designed and fabricated to demonstrate the high absorption properties in the case of ultra-thin thickness. In addition, a reflective spectroscopy system based on a vector network analyzer is built to test the absorption performance. The measured results, showing that it has an absorptivity of close to 97% at 94 GHz, are in good agreement with simulations.