Broadband Microwave Attenuator Based on Few Layer Graphene Flakes

Abstract

This paper presents the design and fabrication of a broadband microstrip attenuator, operating at 1–20 GHz, based on few layer graphene flakes. The RF performance of the attenuator has been analyzed in depth. In particular, the use of graphene as a variable resistor is discussed and experimentally characterized at microwave frequencies. The structure of the graphene-based attenuator integrates a micrometric layer of graphene flakes deposited on an air gap in a microstrip line. As highlighted in the experiments, the graphene film can range from being a discrete conductor to a highly resistive material, depending on the externally applied voltage. As experimental evidence, it is verified that the application of a proper voltage through two bias tees changes the surface resistivity of graphene, and induces a significant change of insertion loss of the microstrip attenuator.