beam steering of a terahertz semi bow tie antenna using parasitic graphene ribbons

In this paper, a reconfigurable beam-scanning planar antenna is proposed in terahertz frequencies. the presented structure consists of a semi bow tie antenna surrounded by circularly arranged parasitic pieces of graphene. the performance of the proposed antenna is investigated considering three different states where a pec ground plane and a graphene ground layer with chemical potentials 0 (mode a) and 1 (mode b) are utilized at the bottom of the substrate. the proposed antenna is designed for utilization at a specific frequency of 1.2 thz in all these three states. the achieved antenna boresight and radiation pattern are altered through changing the conductivity of parasitic graphene elements and ground plane, which is obtained by controlling the corresponding chemical potential of the graphene segments. in addition, the parasitic graphene elements, located around the antenna, provide a high degree of freedom for altering the radiation pattern and antenna boresight. the parasitic elements operate as directors in modes a and b, whereas they act as reflectors in pec ground state. moreover, a high beam steering capability is obtained as chemical potentials of graphene elements are allocated between 0 and 1, whereas a pec ground layer is employed at the bottom of the antenna. it should be noted that the gain and front-to-back ratio of the antenna are controlled using different chemical potentials of the graphene elements. a wide range of scan angles allocated between 0 and 180°, and toward the left and right directions in constant φ plane is achieved for the designed antenna.