Microwave Programmable Graphene Metasurface

The past few years have witnessed the great success of graphene in controlling the electromagnetic (EM) wave. As an important topic in both the physics and engineering fields, wavefront control has attracted more and more attention from the researchers. So far, most graphene-based wavefront control is studied in terahertz or higher frequencies. In the microwave band, relevant work is rarely reported, which is limited by the nearly purely resistive property of graphene, the lack of reactance makes phase control a difficult problem. In this paper, we present and experimentally realize the microwave programmable graphene metasurface (MPGM) for the first time. By analyzing the equivalent impedance, the necessary condition of achieving a binary element using resistive material is first derived. Inspired by which, the proposed structure can realize uniform reflection amplitude and opposite phase simultaneously through changing the voltage applied to graphene. Meanwhile, the patterned configuration makes it possible to control different elements independently. As a result, both simulated and measured results indicate that our MPGM can realize multiple functions such as beam redirecting and radar cross section reduction, paving the way for graphene in the application of designing tunable phase-based devices in the microwave band.