Reflectarray 2D Beam-Steering With Graphene on Copper Elements for 6G Point-to-Point Communication

This work presents a graphene-based Reconfigurable Reflectarray Antenna (RRA) for 6G pointto-point communications. Unlike the conventional dimensions of less than λ/8 to act as the main resonant element, Graphene has been designed at λ/2 dimensions, which works as the phase-shifting element under a copper patch. Graphene’s chemical potential can be varied by applying DC biasing to array elements so that the reflection coefficient phase of the unit cells can be adjusted to form a collimated beam in a certain direction. An array of 977 elements with an aperture diameter of 15λ produced a collimated beam through two states of DC biasing to graphene, i.e. “On” and “Off”. Later, the beam steering performance of the designed RRA was analysed in the E-plane and H-plane. Furthermore, the effect of the focal length to diameter ratio (F/D) is also evaluated on the highest gain and the steering range. The highest gain of 25.6 dBi was obtained at 125 GHz with a beam steering range of ±30° with a gain loss of 3 dB when the F/D ratio was 0.9. However, the best beam steering range of ±45° with a gain loss of 3 dB was obtained when the F/D ratio was 1.1 and the highest gain of 23.25 dBi. Overall, the aperture efficiency was found to be 13% which is sufficient compared to conventional phase shifters at high frequencies. The 1-dB gain of the designed array was found to be 8.8%, 7.2% and 6.4% in the case of F/D ratio of 1.1, 1.0 and 0.9, respectively. Owing to the broadband operation from 122 GHz to 128 GHz, beam steering range, and aperture efficiency, the designed RRA shows the potential to be incorporated with reconfigurable intelligent surface (RIS)-based communications for 6G point-to-point communications.