High figure-of-merit compact phase shifters based on liquid crystal material for 1-10GHz applications

A liquid crystal (LC) based tunable microstrip line (ML) phase shifter featuring high performance is presented. The experimental results show an electrically tunable differential phase up to 360° at 10GHz with an overall insertion loss <8.5 dB. The device possesses a high figure-of-merit (FoM) of 64°/dB at 9.8GHz and 60°/dB between 7-10GHz. This is achieved by simultaneously considering both of the LC tuned phase and overall loss in the design. The proposed device utilizes the inverted meander ML technology to minimize its size. Taking into account the real fabrication procedure, a novel impedance matching structure is applied, and the measured return loss is considerably improved. The FoM and phase tuning property of the fabricated device as optimized are compared with the state-of-Art results published recently and show better performance for both of them.