Thermochromic metal oxides with a Mott transition, such as vanadium dioxide (VO2) exhibit an extensive alteration in
their infrared reflectivity when heated above the transition temperature. For VO2 the infrared reflectivity increases as the
material becomes more metal-like above the transition temperature at 68°C.
Given these dynamic electromagnetic properties in the IR-range, it is interesting to study the reflection of the material
also in other wavelength ranges. The microwave properties of VO2 as a function of temperature have been investigated
Measurements were made with an automated network analyzer combined with an electrical heating unit.
Reflection properties of VO2 in the microwave region were determined.
Above the transition temperature, an increase in the reflection of the surface was observed. The VO2 became more
metal-like in the whole measured microwave frequency range, as in the infrared region.
It is concluded that VO2 not only can be used to adapt the thermal emissivity of a surface but also to control the
microwave reflectivity. Possible applications are switchable radomes, switchable radarabsorbers and heat protection for