Design and analysis of Minkowski fractal shaped metasurface absorber with broadband and polarization-insensitive characteristics using a tunable graphene layer for terahertz applications

The proposed research article's main goal is to demonstrate a terahertz (THz) broadband absorber for high-speed wireless communication applications. The proposed structure is a compact one and possesses three layers. The ground layer acts as a metal reflector, lossy silicon acts as a dielectric material and finally a graphene layer in the shape of a minkowski fractal acts as a radiating patch for the proposed design. We have chosen a thickness of 5 mu m for the lossy silicon which has a dielectric constant of 11.90. The bottom layer of the proposed design contains a good conductive material like gold with a conductivity of 4.561 e+007 s m-1 with a thickness of 0.2 mu m. The thickness of a monolayer graphene is one nanometer, and the overall unit cell size of the proposed structure is 12 x 12 mu m2. Because of its symmetrical nature, the proposed absorber offers a broad response to both TM and TE modes irrespective of any polarization angle. The proposed absorber can operate in the terahertz frequency range and has achieved two broad frequency bands from 3.34-3.98 THz and 4.6-5.30 THz, with an absorption percentage greater than 90. We can observe peak absorption frequencies at 3.60 THz and 5.04 THz, which exhibit an absorption percentage close to unity. Additionally, we validated the proposed broadband absorber using an equivalent circuit approach and verified it using the ADS tool.