Dynamically Tunable Substrate-Integrated-Waveguide Attenuator Using Graphene

In this paper, a dynamically tunable substrate-integrated-waveguide (SIW) attenuator using graphene is first presented. Two graphene sandwich structures are placed inside an SIW, which serve as conductivity-tunable E-plane septum. By applying biased voltage to the graphene, the attenuation can be dynamically changed; meanwhile, the reflection can still keep at a relatively low level. A closed form of the attenuation is also proposed, and the mechanism of the attenuator is theoretically analyzed in detail. Furthermore, a prototype operating from 7 to 14.5 GHz has been fabricated and measured. Both the theoretical calculation and the numerical simulation results have a good agreement with the experimental results, which present the attenuation ranges from 2 to 15 dB with a stable 7.5-GHz wideband while the bias voltage changing from 0 to 4 V.