Theoretical and Experimental Investigation of Thermo-Tunable Metal–Insulator–Vanadium Dioxide Coplanar Waveguide Structure

This paper presents a thermo-tunable metal-insulator-vanadium dioxide (MIV) coplanar waveguide structure (CPW). An analytical quasi-TEM model is used to thoroughly study the structural and material-dependent characteristic parameters of the device, while the temperature-dependent broadband permittivity and conductivity of the deposited vanadium dioxide (VO2) thin film at microwave frequencies are experimentally extracted. The designed thermo-tunable MIV-CPW, focused on its slow-wave properties, shows a drastic increase in slow-wave factor when the temperature of the VO2 thin film is increased over its transition temperature. This phase change allows converting this composite structure into the metal-insulator-semiconductor coplanar slow-wave structure. This demonstrates the potential of such MIV-CPW for the design of tunable and reconfigurable integrated microwave passive components with a significantly reduced size.