Research On Design Method Of Holographic Electronically Controlled Scanning Antenna Based On Liquid Crystal

Compared with mechanical scanning antennas,there are many advantages for the phased array antennas,such as fast scanning characteristic,quickly communication link establishment,and multi-target tracking.However,phased array antennas are expensive due to a large number of TR modules so that they can only be applied on a small scale and cannot be widely popularized.In recent years,the liquid crystal holographic electronically controlled scanning antenna has attracted much attention as a low-cost alternative technology for phased array antennas at home and abroad.At the same time,this technology is only mastered in the United States,because of the huge commercial benefits involved,and the relevant public information is very scarce.Aiming at the above problems,this paper studies the working mechanism and design method of the liquid crystal holographic electronically controlled scanning antenna.By using the electrical control characteristics of the liquid crystal and combining with the holographic beam control algorithm,two liquid crystal based holographic electronically controlled scanning antennas are proposed.And verified the correctness of the design method through full-wave electromagnetic simulation.In the paper,firstly,the holographic beam control algorithm was improved and the research results have shown that the improved algorithm has higher pointing accuracy and can effectively improve the beam of the liquid crystal holographic electronically controlled scanning antenna's scanning range.If the original algorithm happens to point in the direction of expected radiation,the two algorithms are the same.If the original algorithm has pointing error,the improved algorithm can improve the pointing accuracy of 1°?3°.Using the original algorithm,the beam scanning range is-55°?45°,and the improved algorithm can reach-55°?50°.On the basis of the above research,this paper designs a liquid crystal control antenna unit with parallel plate waveguide and a substrate integrated waveguide as as the feed network carrier,and the corresponding one-dimensional holographic electronically controlled scanning antennas.For the liquid crystal holographic electronically controlled scanning antenna fed by the parallel plate waveguide,the index it reached is that the S21 of the unit at the resonance point is about-2 d B,while S11 is better than-15 d B,The radiation efficiency of the antenna unit is 38%,the energy switching ratio is 15.43,and the scanning angle range is-55°?50°.For the liquid crystal holographic electronically controlled scanning antenna with substrate integrated waveguide feeding,its index is that the S21 of the unit at the resonance point is about-1 d B,while S11 is better than-20 d B,the antenna unit radiation efficiency is 54%,the energy switching ratio is 26 and the scanning angle range is-60°?55°.Finally,this paper studies the design method of two-dimensional liquid crystal holographic electronically controlled scanning antenna array.Firstly,a one-to-eight power distribution network based on dielectric integrated waveguide is designed.Its index is that S11 is better than-13 d B in the full frequency band,the energy obtained by the middle four channels is closer,and the four channels on both sides are slightly smaller.The middle The six channels and the two channels on both sides have little phase difference after being converted to 360 degrees.Then,power distribution network is combined to the aforementioned liquid crystal holographic electronically controlled scanning array are combined to.finally design a two-dimensional liquid crystal holographic electronically controlled scanning antenna array design,which realizes the beam scanning under the condition of ? <45°.