A broadband planar THz metamaterial absorber

We propose the design of a broadband planar metamaterial absorber (MA) at terahertz frequencies. The unit cell of the MA is composed of four dual-band sub-cells with different dimensions in a coplanar. The four dual-band sub-cell structures resonate at several neighboring frequencies. The absorber consists of two metallic layers separated by a dielectric spacer. Simulation results show that the metamaterial absorption at normal incidence is above 90% in the frequency of 6.56-8.10 THz. This design provides an effective way to construct broadband absorber. The multiple-reflection theory was used to explain the absorption mechanism of our investigated structures. The coupling of adjacent four dual-band sub-cells can introduce additional capacitance to affect the performance of absorber.