Frequency Reconfigurable and Radiation Pattern Steering of Monopole Antenna Based on Graphene Pads

This paper presents a reconfigurable band of operation from 5G to 4G for radio frequency energy harvesting (RF-EH) in the different wireless communication bands. The designed antenna with steerable beam pattern based on tunable of the graphene pads. The proposed antenna consists of printed CPW-fed circular monopole shaped and five rectangular strips are added with equally separation angle 45 degrees . These strips are connected with monopole by using graphene pads. The monopole antenna resonates at 5G applications extended from 3 GHz up to 7.8 GHz at -10 dB reflection coefficient with Omni-radiation pattern over the operating band without any bias voltage of the graphene pads. By applying the dc voltage to the graphene pad the rectangular strips are connected to the monopole and the designed antenna start to resonant from 1.8 GHz to 7.5 GHz to add the 4G wireless applications. The steering of the beam from 60 degrees to -60 degrees according to the graphene pad that connect to the monopole. The graphene pad exhibits as variable resistance from almost short to open circuit with and without voltage bias, respectively. The designed antenna is simulated using High Frequency Structure Simulation (HFSS) Ansys ver. 19. The simulated equivalent circuit of the graphene is applied then reduced graphene oxide (RGO) pads are deposited to validate the results. Fabricated prototype is then used to experimentally validate the simulation results. Finally, Reflection coefficient and radiation pattern measurements and simulations are presented, good agreement between these results.