Design of a Ka-band low-cost microstrip line phase shifter and a sum-difference beam antenna based on liquid crystal technology

This letter presents a Ka-band low-cost microstrip line phase shifter based on liquid crystal (LC) technology. Furthermore, a sum-difference beamforming antenna array based on the LC phase shifter is designed. The phase shifter is composed of two coaxial connectors, a metal base, an intermediate dielectric layer, a gradient metal sheet and a top glass layer. The simulated results show that a nearly 360° phase shift coverage can be achieved with the effective permittivity of LC varying from 2.5 to 3.5. The sum-difference beam antenna array is composed of a circulator, a sum-difference network, a one-to-eight power-division network, eight liquid crystal phase shifters, and a serious fed antenna array. The simulation results show that the antenna array can achieve sum-difference beam scanning range of ±30°. A prototype of LC phase shifter is fabricated and tested. The results show that the designed LC phase shifter can achieve a 360° phase coverage by applying a direct current (DC) voltage ranging from 0 to 12 V. Compared to traditional phase shifters, the proposed design offers a simple structure at a lower cost. When applied in the design of a sum-difference beam antenna array, it can reduce the producing cost and enable integrated design.