A large angle tunable triple-band metamaterial absorber

A tunable metamaterial absorber that can be used in the microwave band is presented in this paper, which consists of two metal rings of proportional length and a cross-shaped resonator (CSR). With three independently adjustable operating bands (C and X-band) in the frequency range of 5－12 GHz, the peaks are located at 6.36 GHz, 7.96 GHz and 12.12 GHz, with absorption rates of 0.937, 0.999 and 0.993, respectively. The absorber can maintain high absorption when incidents at a large angle. In addition, the tunability of the design structure is studied. When the top layer of vanadium dioxide (VO₂) is in the all-metal state, there are three absorption peaks in the microwave segment, and the maximum absorption rates are 0.939, 0.827 and 0.92, respectively. Since the conductivity of VO₂ varies from 200,000 to 30,000 S/m, the absorption is dynamically adjustable at three absorption peaks. The results of the structure have a potential application prospect in multi-band sensor detection.