Nanostructured graphene metasurface for terahertz cloaking of elliptical cylinders and metallic strips

Here, we propose the analytical framework for electromagnetic cloaking of dielectric and metallic elliptical cylinders with a nanostructured graphene metasurface at low-terahertz frequencies. The analysis is based on the solution of the scattering problem in terms of elliptical waves given by the radial and angular Mathieu functions with the sheet impedance boundary conditions at the graphene metasurface, having closed-form expression for the surface impedance. The scattering cancellation occurs for all the incident angles and all the scattering angles with a specific value of surface reactance of graphene nanopatches. A special case of cloaking with the elliptically shaped metasurface concerns a 2-D metallic strip represented as a degenerated ellipse, such that the focal points of the elliptical cloak coincide with the edges of the strip. It is shown that the nanostructured graphene metasurface with the same geometrical parameters can be used for cloaking of elliptical cylinders of different dimensions, including the case of a strip, by varying the Fermi energy of graphene.