Evolution of Microwave Nematic Liquid Crystal Mixtures and Development of Continuously Tuneable Micro- and Millimetre Wave Components

Abstract

This work represents the evolution of micro- and millimetre wave optimized nematic liquid crystal mixtures and their applications. Starting with the well-known liquid crystal mixture K15 used in the display technology, microwave optimized LC mixtures have been developed. For that, novel characterization setups have been developed, which play an essential factor in the optimization process for the micro-, millimetre wave and THz regime. By using a specialized LC simulation tool, different tuneable waveguide topologies are compared in terms of tuneability, transmission loss and tuning speed. Based on that, a phase shifter for W-band frequencies has been fabricated, which reached a measured figure of merit for passive phase shifters of up to 148° /dB.