Broad-band microwave characterization of liquid crystals using a temperature-controlled coaxial transmission line

Abstract

Liquid crystals (LCs) promise to be suitable passive tunable material for microwave devices with excellent features concerning tunability and losses. In order to optimize the synthesis of LCs and the design of tunable microwave devices based on them, LCs have to be characterized at microwaves. For a microwave analysis between 360 MHz-23 GHz, use was made of a broad-band characterization method with a two-port coaxial line, temperature controlled within -7/spl deg/C and 115/spl deg/C. Two LCs are investigated: K15, as a quasi-standard, and MDA-03-2838, as a novel mixture with increased dielectric anisotropy and reduced microwave losses tan/spl delta/.