In-House Made Inverted Microstrip Line Phase Shifter Based on Nematic Liquid Crystal

Abstract

Nematic liquid crystals are anisotropic dielectrics whose properties could be controlled by surface anchoring, external electric or magnetic fields. A typical design method of tunable inverted microstrip line phase shifter based on liquid crystal for microwave application is investigated. Two phase shifter designs based on the proposed method were introduced with the center operation frequency of 10 GHz and 20 GHz respectively. The prototype design operating at 20GHz is manufactured. The dielectric anisotropy of the liquid crystal used for the prototype is 0.45. A differential phase shift of 27.2 • was achieved at 20 GHz with the physical length of 20 mm, connected to two coplanar waveguide ports of 50 ohms through vias, and under an external bias of 7 V.