Liquid Crystal Material for Microwave Applications

Abstract

Liquid crystal (LC) molecules feature an additional state of matter, which exits between a liquid and a solid state. In this state, the LC molecules can flow even though they have orientational order. The molecules can be formed in plenty of different forms depending on how the constituents are bonded. These forms are mainly in a rod- or disk-like shape. The shape anisotropy results in different physical phenomena such as the liquid crystal mesophase (form Greek, mesos \(=\) middle), anisotropies in the reflective index, in the magnetic susceptibility and in the dielectric properties. These fundamental properties of rod-like shape nematic liquid crystals are presented in Sect. 2.1 in accordance with the scope of this work. In Sect. 2.2 it is aimed to give reader insights into LC based planar microwave devices. Hence, required technology and working principle of a variable delay line are presented.