Graphene-Based Dynamically Tunable Attenuator on Spoof Surface Plasmon Polaritons Waveguide

A dynamically tunable attenuator is proposed by integrating two graphene sandwich structures (GSSs) into a spoof surface plasmon polaritons (SSPPs) waveguide. The attenuator is formed by locating two GSSs symmetrically on both sides of the SSPP waveguide. Both the surface impedance of GSSs and the attenuation of the attenuator are tunable by changing the bias voltage applied to the graphene sheets. The transmission line theory is employed to model the proposed SSPP waveguide and attenuator. Measurement shows two orders of magnitude attenuation range with bias voltage changing from 0 to 4 V. In addition, the proposed SSPPs attenuator achieves 2.5-7.2 times attenuation/λ of GSS compared with the reference works.