Performance Analysis of Hybrid Metal–Graphene Frequency Reconfigurable Antennas in the Microwave Regime

This paper analyzes the potential application of graphene in microwave frequency reconfigurable antennas. Two multiband designs, one for wireless fidelity (WIFI), covering the frequency bands of 2.4, 3.6, and 5 GHz, and another for the cellular long-term evolution system, operating the frequency bands of 1.8, 2.5, 2.6, and 3.6 GHz, are evaluated to demonstrate the working principle and the performance tradeoffs. The designs are made mostly of copper with some parts made of graphene to enable reconfigurable behavior. The graphene material's surface impedance is tuned by applying a direct current bias voltage, which allows to obtain one of two extreme values that emulate the ON and OFF states of common switches, such as microelectromechanical systems (MEMSs), field-effect transistor, and p-type insulator n-type diode, or continuous values to mimic reconfigurable antennas loaded by varactors. This material switching modifies the electrical length of the current propagating through the antenna and consequently switches the resonant frequencies. Additionally, results show that hybrid metal-graphene frequency reconfigurable antennas can, at the same time, provide a tunable bandwidth and antenna matching.