Recent developments in metamaterial designs have opened up the possibility of the absorption in the terahertz frequency range. In this paper we present a multi-resonant perfect absorber that can be tuned to produce either single wideband or multi-band resonance in order to suit any special requirements. We demonstrate that the proposed structure leads to the absorption peaks in terahertz regime. This periodic metal-backed structure consists of a metallic ring positioned on a graphene nano-ribbon per unit cell. In addition, we derive the equivalent circuit and transmission line model based on the reflected fields to facilitate analysis of the proposed design and comprehension of full-wave simulation results.
