Multi-band terahertz metamaterial absorber composed of concentric square patch and ring resonator array

Abstract

An equivalent circuit model (ECM) to analyze a single-layered graphene multi-band metamaterial absorber was developed. This absorber consists of concentric square patch and ring resonator arrays and operates in the terahertz (THz) region. To validate our analysis based on the ECM, we also conducted numerical simulations using the finite element method (FEM) within CST software. Additionally, we have explained the absorption behavior of the metamaterial using the coupled mode theory (CMT). This absorber design, with its single-layer structure, tunability, and triple absorption bands, offers promise for applications in THz devices and systems. Notably, it achieves an average absorption of 99% for three bands and the absorption reaches 100% in the frequency range of 4 to 6.5 THz. The correlation of ECM and CMT analyses with the FEM simulations validate the accuracy and the effectiveness of these simplified approaches in comprehending the resonant characteristics of the metamaterial absorber.