Thermally Tunable Frequency-Selective Surface Based on VO(2)Thin Film

An approach to a design of tunable frequency-selective surfaces (FSSs) for radio frequency (RF) domain based on vanadium dioxide (VO2) thin films is proposed. As an example, a thermally tunable annular slot FSS with integrated VO(2)switchable elements for C-band of the RF domain is described. Switching is based on abrupt change of conductivity of the VO(2)film, initiated by heating from room temperature to a temperature of the metal-insulator phase transition of 44 degrees C. A tuning mechanism of the FSS allows continuous change of frequency response from room temperature state, where the FSS acts as a band-pass filter, to high-temperature state, where the FSS works as a reflector. In the process of tuning, a reflection coefficient at a central frequency of the filter can be increased from -26.4 dB up to -2.2 dB. The proposed approach can be used for the design of tunable FSS for applications that allow thermal control of the frequency response.