Reconfigurable graphene reflectarray with switchable focus

A reconfigurable graphene reflectarray (RGRA) is proposed with the electrically switchable focus for incident (quasi-)spherical waves. The geometry- and chemical potential-dependent reflection phase is explored for the reflective graphene patch cells, which is further assigned to specific parts of the RGRA. The full-wave simulated results demonstrate that the proposed structure can provide a dynamically controllable focus at 1.5 THz. The peak realized gain and the radiation efficiency are higher than 22 dBi and 65%, respectively, for both the short and long focuses of 3.2λ and 8.0λ.