Dynamically Tunable Four Band Filtering Attenuator Based on Graphene Integrated Microstrip Multi-mode Resonator

In the paper, a multi-mode microstrip resonator was designed which used to form a four band filtering attenuator with controllable attenuation band. Firstly, the graphene sandwich structure was loaded on the microstrip open/short-circuit resonator to analyze the influence on the resonant modes. Secondly, a multi-mode resonator with eight-mode is designed whose passband were centered at 1.1, 1.5, 1.9 and 2.3 GHz, respectively. Two GSSs was loaded on the upper branch of the resonator which provide attenuation function for the first two passband and other two GSSs was loaded on the lower branch of the resonator that provide tunable attenuation for the last two passband. By varying the voltage of the upper GSS_S, controllable attenuation from 2.1 dB to 7.4 dB and 4 dB to 12 dB can be obtained at the first or the second band, respectively. Similarly, controllable attenuation from 2.4 dB to 9.5 dB and 3.6 dB to 11 dB can be obtained at the third or the fourth band by varying the voltage of the lower GSS_S. Finally, a four band filtering attenuator with dynamically tunable attenuation and controllable attenuation band can be designed based on graphene integrated microstrip multi-mode resonator.