Improvement of decay time in nematic-liquid-crystal-loaded coplanar-waveguide-type microwave phase shifter by polymer stabilizing method

Polymer stabilization by UV light irradiation in nematic liquid crystals is proposed to improve the decay time of coplanar-waveguide-type microwave phase shifters. The effect of polymer concentration on the decay time of polymer-stabilized nematic liquid crystals is confirmed by a dielectric experiment on a liquid-crystal-sandwiched indium-tin-oxide (ITO) glass cell before loading into a coplanar-waveguide-type microwave phase shifter. The decay time, phase shift value, and insertion loss of microwave phase shifters with different polymer concentrations are measured. The decay time of polymer-stabilized nematic liquid crystals in the microwave phase shifter markedly decreases compared with that of pure nematic liquid crystals. It is confirmed that the use of polymer-stabilized nematic liquid crystals is effective to improve the response time of microwave phase shifters.