Design of an ultra-wideband and switchable VO₂-based microwave absorber

We propose a design of an ultra-wideband microwave metamaterial absorber using Vanadium dioxide (VO₂) based on a dual-layer structure. The ultra-wideband absorption performance of the proposed structure can switch by using the phase transition of VO₂. When the VO₂ is in the insulator state, the proposed absorber achieves an ultra-wideband absorption response in the range of 3.7-22.5 GHz with an absorptivity higher than 0.9 and a relative bandwidth of 143.5% at normal incidence, which covers the entire bands from the C to Ku. The designed absorber is polarization insensitive and wide incident angle stable for both transverse electric (TE) and transverse magnetic (TM) modes. Owing to the outstanding merits of absorption performance and frequency-tunable capability, our design structure can be suitable for many promising applications in the microwave range, such as smart radar, camouflage and stealth radome technology.