The Measurement And Analysing For The Dielectric Coefficient Of The Liquid Crystal And The Application In Phase Shifter

Liquid crystal has been widely applied to many new areas of technology, as a cross-disciplinary research. Recently, a new type of nematic liquid crystal phase shifter has been successful developped. The phase shifter performances mainly in the microwave and millimeter-wave. With a relatively low voltage, high phase shifter degree and low cost and miniaturization, it has a great future and potential. Nematic liquid crystal phase shifter takes advantage of the dielectric anisotropy of the liquid crystal with and without bias voltages to achieve the aim of phase shift. So the dielectric coefficient of the liquid crystal is the basic parameter for preparing this kind of phase shifter. And researching on it is of great significance.The nature of the liquid crystal material have been measured, and using Zview software, dielectric and impedance spectroscopy of the liquid crystal have been analysed. Exploring the internal structure of the liquid crystal and comparing with the internal structure of ceramics, the conluction that the internal structure of liquid crystal can be equivalent to the RC series circuit has been attemptly made, and the R is variable because of the nature of the liquid crystal; In the measured frequency the main polarization is dipole polarization. The relationship between the dielectric anisotropy and the frequency has been got, and the dielectric anisotropy decreases with the frequency increases under 10KHz-1MHz. Layered structure of the microstrip line liquid crystal phase shifter has been simulated using Ansoft HFSS. The selection of the fundamental principles of materials for preparing liquid crystal phase shifter has been obtained. That is, the upper substrate thickness as small as possible and low dielectric coefficient and high dielectric anisotropy of the liquid crystal. The principles will play a guidance role to the actual design of the liquid crystal phase shifter.