▎ 摘　　要

A wideband microwave absorber with dynamically tunable absorption is proposed in this letter. It consists of a few layers of large-area graphene and a layer of random metasurface. Through the superimposition of a few layers of graphene, the tunable range of graphene sheet resistance is lowered to 80-380 ohm sq, which is more suitable as the resistance film of broadband microwave absorber, because it is easier to match the impedance of free space. In addition, by choosing 12 proper elements of metasurface and distributing them randomly, more resonance frequencies and phase responses can be achieved, thus improving the bandwidth of the microwave absorber and reducing its profile simultaneously. By tuning the sheet resistance of graphene via bias voltage, the absorbance of proposed absorber can be tuned from 80 to 50 in a wide bandwidth from 5 to 31 GHz. The prototype of proposed absorber is fabricated and measured. The reasonable agreement between the simulated and measured results verifies the accuracy of our approach.