Tunable mantle cloaking utilizing graphene metasurface for terahertz sensing applications

Design of sensors which are able to probe electromagnetic radiation with larger cross section and at the same time with having negligible perturbation in measurement has attracted significant attention. For this purpose, scattering-cancellation sensors or cloaking sensors are introduced. However, tunable cloaking sensors are very challenging. In this regards, here, a metasurface based on graphene strips is proposed to cloak a dielectric cylinder under illumination of TE_z and TM_z polarized incident waves in terahertz range. According to the in plane effective surface impedance tensor for the considered metasurface and the required surface impedance for achieving invisibility under TE and TM polarized impinging waves, the geometrical parameters of the covering structure and characteristics of graphene are obtained. Numerical simulations show radar cross section reduction for both TE and TM polarizations. Furthermore, the introduced metasurface is able to cloak the cylinder for incoming waves with circular polarization. In addition, it is shown that by properly adjusting the chemical potential of graphene, the required surface impedance to have cloaking for the two polarizations in other frequencies can also be achieved, which results in a tunable dual polarized cloaking. The proposed structure provides 2-11 dB reduction in scattering strength relative to the uncloaked configuration for 0.3eV variation of graphene chemical potential.