Use of Thermochromic Properties of VO2 for Reconfigurable Frequency Selection

The thermochromic nature of vanadium dioxide (VO2) has facilitated many promising applications for reconfigurable frequency selectivity. The phase-changing property of VO2 was used to realise a reconfigurable frequency-selective surface (FSS) capable of manipulating electromagnetic waves for different functionalities. Diffractive optical elements (DOE) are used for diffracting laser beams to form conductive FSS images on the VO2 wafer for frequency selectivity. The dipoles on the VO2 wafer generate a stop band response of 12 dB and 10 dB for unit cells of the single dipole and double dipole at 3.5 GHz, respectively. A 10 GHz FSS array is projected by DOE on the 2-inch VO2 wafer with a filtering effect of 13 dB at 9.5–10.5 GHz. This solution is used to design a radar cross-section (RCS) modification FSS with reflected waves of about 20 dB higher reflectivity in the backscattering direction than in the specular direction.