Large angle beam steering THz antenna using active frequency selective surface based on hybrid graphene-gold structure.

Numerous studies have been made to design pattern reconfigurable THz antennas to achieve optimum performance for particular environmental conditions. However, it is still a challenge to achieve large angle beam steering for reconfigurable antenna in terahertz band. Here we propose a 360-degree beam steering THz antenna using active frequency selective surface (AFSS) based on hybrid graphene-gold structure. The proposed antenna consists of a THz omnidirectional monopole antenna coated with a hexagonal AFSS screen. By adjusting the chemical potential of graphene from 0 to 0.5eV, the AFSS unit cell can be switched from ON state (high transmission) to OFF state (total reflection) in terahertz, which can steer the beam direction as the monopole antenna is surrounded with six parts of AFSS screen with different ON/OFF states. In this way, the antenna can achieve beam scanning covering 360 degrees. Moreover, unlike the conventional AFSS with only two states, the reflection and transmission coefficient of the proposed AFSS are continuously variable due to the tunable chemical potential, which allows the radiation gain of antenna to be enlarged or suppressed. This antenna may serve the reconfigurable THz wireless system with flexible beam direction and gain level.