Measurement and analysis of RIS device utilizing a substrate switching technique at 5.8 GHz frequency

Abstract

Vanadium dioxide (VO2) is a potential material for reconfigurable intelligent surface (RIS) in future wireless network communication. It has unique phase transition properties and tuneable optical and electrical characteristics. This thesis explores the design, building, and testing of PCM PCM-based RIS prototype that uses VO2 nanocellulose as a phase-shifting material.

The work started with preparing different VO2 nanocellulose films and then measuring the resistivity of the films at different temperatures. After getting the suitable VO2 films then the permittivity, loss tangent, and conductivity measurement has been done. After that, the RIS prototype design and fabrication process was completed. The RIS measurement setup was one of the core parts of this research. It started right after the prototype fabrication.

When everything was ready then it came to the RIS measurement process. First, the prototype-1 LM890 Au1% (9.10.24) was measured. To ensure the measurement result and accuracy, the prototype-2 SM95-a (24.20.24) was built and measured. However, the measurement result did not match the simulated data. After that, the prototype-3 SM95-a Overcast (21.11.24) was built and there was a slight design change in the top metal layer. This time the measurement data was better than the previous two prototypes. The measured phase shift was 75 degrees for the prototype-3 while the simulated phase shift was 78 degrees. Therefore, it was successful research and the research objectives were successfully met.