Nematic liquid crystals in inverted microstrip structures
Jerzy Piotrowski , Janusz Parka , Edward Nowinowski-Kruszelnicki
AbstractNematic liquid crystals are promising dielectrics for tunable microwave devices due to their significant birefringence and moderately low loss. Dielectric anisotropy or refractive index anisotropy of liquid crystal is one of the important parameter for the design of variety of reconfigurable devices. In this work, transmission line method is used for the broadband investigation of nematic liquid crystals in the frequency range of 1-10 GHz. For this purpose, a measurement device is proposed with a tunable liquid crystal transduces based on an inverted microstrip structure section placed between two segments of layered microstrip lines terminated by microstrip-coaxial line transitions. Measurements of the scattering parameters of the device with standard liquid crystal 6CHBT as well as with a novel highly anisotropic mixture W1825 have been conducted. Based on these measurements, a high effective refractive index anisotropy of 0.31 for the W1825 mixture compared to 0.12 for 6CHBT have been determined. These values are lower of 26% and 18% than anisotropy of the refractive indices appointed by a resonator method for W1825 and 6CHBT, respectively. Progress in highly anisotropic mixtures opens new low-cost liquid crystal applications in microwave devices.
|Book||Szczepański Paweł, Kisiel Ryszard, Romaniuk Ryszard (eds.): Proceedings of SPIE Electron Technology Conference 2013, vol. 1, no. 8902, 2013, P.O.Box 10, Bellingham, Washington 98227-0010 USA, SPIE, ISBN 9780819495211, 752 p., DOI:10.1117/12.2033297|
|Keywords in English||nematic liquid crystals, inverted microstrip line, tunable liquid crystal transducer, microwave phase shifters, passive circuits,|
|Score|| = 10.0, 24-01-2020, BookChapterMatConfByIndicator|
= 15.0, 24-01-2020, BookChapterMatConfByIndicator
|Publication indicators||= 3; = 1|
|Citation count*||7 (2020-09-14)|
* presented citation count is obtained through Internet information analysis and it is close to the number calculated by the Publish or Perish system.