Design of a tunable microwave absorber based on vanadium dioxide

In order to obtain the tunable absorption spectrum of TE wave in THz band, a tunable THz absorber based on vanadium dioxide was designed by full-wave simulation. Absorption spectrum, electric field, surface current and energy loss of the absorber were analyzed. The effects of structural parameters h₄, k and incident angle θ on absorption frequency domain and absorption bandwidth were discussed. The simulation results show that, tunable absorption spectrum can be obtained and absorption performance of the microwave absorber can be improved by changing the physical characteristics of vanadium dioxide resonator unit through external temperature control. When T≥68℃, broadband absorption of microwave absorber can be achieved in 2.70THz~3.36THz band. Absorption rate is above 90% and relative bandwidth can reach 21.8%. When T < 68℃, multiple single frequency points can be absorbed. The position of absorption frequency point and absorption bandwidth can be changed by changing the structural parameters h₄ and k. The absorption effect can be affected by changing incident angle θ. This study is helpful for further research of tunable terahertz devices.