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 30,000 S/m to 200,000 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.