Characterization of Dielectric Properties of Nematic Liquid Crystals Using an Optically-Transparent Microstrip Resonator at 5 GHz

This work reports the design, simulation, and fabrication of an optically-transparent microstrip line resonator that is employed to characterize the dielectric properties of a nematic liquid crystal (LC) at a frequency of 5 GHz, to understand the behaviour of LC-based optically-transparent radio frequency devices, and to allow direct observations of the LC through a polarising optical microscope while operating the device. The microstrip line is constructed by etching indium tin oxide (ITO) coated glass and exploiting the first-order resonance to infer the anisotropic dielectric properties of the nematic LC. Results are compared with a microstrip line device featuring the same geometry but constructed from FR-4 and copper, and full-wave electromagnetic simulations that suggest an accuracy of 95% in the LC dielectric properties.