Measurement of dielectric properties of liquid crystal in microwave frequency range

摘要

Dielectric properties of some types of nematic liquid crystal(LC) were measured using coaxial lines in microwave frequency range. The measured dielectric properties were evaluated in terms of the types of LC, so that one of the indications to know what type of LCs should be selected for material of microwave devices was obtained. The results show cyano-containing LCs have large birefringence and low loss tangent, fluoro-containing LCs have low loss tangent, and negative nematic LCs have small birefringence and large loss tangent. In addition, dielectric properties of LCs were also measured by the resonator method to verify the coaxial lines method.