The Structure Design of a Microstrip Tunable Attenuator Based on Few-Layer Graphene

There are innovative applications for graphene materials in microwave Radio Frequency (RF) due to their unique optoelectronic properties. In this paper, a series of existing tunable microstrip attenuators based on few-layer graphene are compared and studied, and a new microstrip tunable attenuator based on few-layer graphene is proposed on this basis. Firstly, the relationship between the performance of different pair spacing attenuators with 4 pairs of graphene structures is analyzed based on the existing pair spacing studies with 1-3 pairs of structures; after that, the performance characteristics of the existing 1-4 pairs of graphene structures on different substrates are tested and analyzed; finally, a new tunable attenuator structure is proposed based on the above research results. The new attenuator consists of four parts, including a dielectric substrate, a microstrip line, a total of five pairs of graphene flakes on both sides and corresponding metal vias. The resistivity of the graphene flake can be changed by changing the access bias voltage, thus regulating the insertion loss of the attenuator. The experimental results show that the proposed attenuator can operate in the frequency range from 3 GHz to 10 GHz, and the insertion loss can be adjusted from -2 dB to -63 dB, with a high tunable performance of 61 dB.