P‐130: Liquid‐Crystal‐Based Discrete Phase Shifter for Improving Response Speed

Liquid crystals (LCs) have a characteristic in which the dielectric constant changes depending on the rearrangement of the liquid crystal molecules according to the voltage. Therefore, they are widely used in research on various circuits in the microwave frequency band utilizing the variable dielectric constant. Research on the phase shifter, a key element of beamforming antennas, is active, and many studies are being conducted to improve performance such as propagation loss, response speed, and phase difference controllable range. This paper proposes an idea to improve the response speed, and the speed at which liquid crystal molecules align greatly varies depending on the size of the applied voltage. Although it is affected by the size of the liquid crystal cell gap, the alignment speed of the liquid crystal molecules becomes much faster as the size of the applied voltage increases, and the response speed increases by more than 10 times as the applied voltage decreases. In other words, the response speed deviation is large depending on the desired phase value. Therefore, in this paper, we propose a design method to reduce the response speed deviation according to the phase difference that occurs due to the use of multiple levels of voltage in a liquid crystal‐based phase shifter, and through actual experiments, we prove that the absolute response speed can be improved while reducing the response time deviation according to the phase value to less than 1/3 compared to the existing method.