Electromagnetic cloaking with metamaterials, primarily based on the coordinate transformation and plasmonic cloaking methods, have been studied with the use of bulk volumetric metamaterials. A different approach has been recently proposed which utilizes the concept of the scattering cancellation by a surface as a mantle cloak. It has been extended to the analytical modeling of practical metasurface cloaks implemented by sub-wavelength periodic printed and slotted arrays. Also, a graphene monolayer and patterned graphene metasurface have been proposed for cloaking of dielectric and metallic cylinders at low-terahertz frequencies.
Here, we present our recent developments in the analytical modeling of metasurface cloaks to significantly reduce the scattering from dielectric and metallic circular and elliptical cylinders at microwave and terahertz frequencies. Metasurfaces are formed by periodic arrays of subwavelength printed and slotted elements for microwave cloaking, and by graphene monolayers and nanostructured graphene patch arrays for low-terahertz cloaking applications. The solution of the scattering problem is based on the Lorenz-Mie scattering theory, and for elliptical configurations the scattered field is represented in terms of radial and angular Mathieu functions. The formulation utilizes a sheet impedance boundary condition with the analytical closed-form expression for the surface impedance of metasurfaces. An interesting case concerns the cloaking of a metallic strip, as a degenerated ellipse, with an elliptical metasurface.
The analytical and numerical full-wave simulation results will be shown for a variety of structures demonstrating the cloaking effect at microwave and low-terahertz frequencies.