Temperature-dependent microwave properties of vanadium dioxide film across the phase transition

Vanadium dioxide (VO 2 ) holds promise for reconfigurable microwave devices due to its rapid phase transition and large conductivity contrast. However, the absence of research into VO 2 's microwave properties across its thermally induced phase transition within the microwave band in existing literature hinders the design and application of VO 2 -based reconfigurable devices. In this paper, we investigate the switchable microwave properties of VO 2 across the phase transition through temperature-dependent S-parameter measurements in an X-band waveguide. The results reveal a non-monotonic variation in absorption, which is attributed to the dynamic interplay between impedance matching and material loss. The absorption peak appears at an intermediate conductivity state, where optimal energy coupling and dissipation are achieved. This behavior is further analyzed by comparing samples with different S-parameter variations. Our findings provide a theoretical and experimental basis for designing VO 2 -based reconfigurable absorbers and modulation devices.