Reflectarray with Graphene and beam steering feature for terahertz communication

A reflectarray with graphene and beam steering feature is presented. It is designed to operate at a frequency band of 3.6 THz. The unit cell is composed of a graphene circular loop connected with four slotted arms printed above the substrate while a complete ground plane is added on the back of it. The reflection coefficients magnitude and phase of the unit cell are investigated. The realization of the beam steering feature is achieved by changing the biasing voltage applied to the graphene cells, which changes the chemical potential (µc) while keeping all cells with the same dimensions. The phase ranges higher than 310^o is achieved by changing the (µc) from 0.02 to 0.2 eV. The reflectarray is composed of 21 × 21 elements with an overall size of 546 × 546 µm². A linearly polarized pyramidal horn antenna is utilized to feed the reflectarray. Finite integration technique-based software is utilized in the simulation process. The gain of 20 dB and 1-dB gain bandwidth of 1.1 THz (30.6%) is achieved. A steering beam extended from – 45^o to + 45^o is achieved by properly adjusting the biasing voltage, which in turn changes the phase distribution of the 21 × 21 elements.