Dielectric Image Line Liquid Crystal Phase Shifter at W-Band

This paper presents a continuously tunable dielectric image line phase shifter operating at W-Band (75 GHz to 110 GHz). The core material of the image line is liquid crystal (LC), by which tunability is obtained. The image line topology offers a small and compact realization when compared to fully dielectric or metallic waveguide-reliant structures and is suitable to a substrate-integrated environment. Four bias electrodes provide the field necessary to tune the LC. A maximum differential phase shift of 352° at 110 GHz is achieved with a bias voltage of ±150 V, while the insertion loss is between 2.8 dB and 4.8 dB. The resulting Figure-of-Merit is 84 °/dB. Response times as low as 5 s are possible with this first realization.