The design and fabrication of a broadband meta-material absorber based on a double-layer ring structure

Abstract

A double-layer meta-material absorber based on two “ring” structures is designed and fabricated in this paper. Each layer contains a different additional microstructure, which has the property of broadening the microwave absorption band. On the top layer we introduce a split on the ring structure, and on the bottom layer we bring in a short wire. According to the simulation results, the absorption band below −10 dB expands beyond 8.6 GHz compared to the original configuration. Moreover, there is a favorable coincidence between the experimental results and the simulations. The surface current and energy distribution of different meta-material structures are compared and analyzed to explain the absorption band expansion. It is shown that the varied distribution pattern of the surface current leads to multiple absorption peaks, which are connected to each other to form a broad absorption band. Moreover, the results illustrate that it is the splitting that causes the decoherence between the surface currents, which generates the frequency dispersion and hence the broadening of the absorption band. The distribution of the electric energy is analyzed and the results show it is the additional wire that forms a toroidal capacitor with the bottom ring to deepen the absorbing band. These results imply a different way of expanding the absorption band of metamaterial absorbers.