Electrically Controlled Antenna Array Based On Liquid Crystal Material

With the development of the times,people's requirements for communication application scenarios are more and more diverse,and multi-functional antennas emerge as the times require,such as multi beam antenna,polarization reconfigurable antenna,frequency reconfigurable antenna and so on.In recent years,as an electrically tunable material,liquid crystal has attracted the attention of antenna researchers,and its characteristics are suitable for the design of reconfigurable antenna and phased array.In this paper,the electronically controlled antenna array based on liquid crystal materials is the research direction,and the main research contents include continuous scanning array antenna and Polarization Reconfigurable Antenna.The main contents of this paper are as followsThe research status of phase shifter and antenna based on liquid crystal materials in microwave and millimeter wave band is reviewed,and the research directions are classified and summarized.Based on the theory of liquid crystal,the physical characteristics and tuning principle of liquid crystal are explored,and the circuit processing technology based on liquid crystal is summarized,which lays the foundation for the subsequent device design based on liquid crystal.In addition,the mathematical modeling is carried out for a deeper understanding of liquid crystal materials.Based on the principle of series fed array frequency scanning and liquid crystal tuning,a two-dimensional continuous scanning array antenna based on liquid crystal material is proposed.Two kinds of liquid crystal phase shifters are designed.The maximum phase shift of E-plane phase shifter is 90 degrees,and the maximum phase shift of H-plane phase shifter is 450 degrees.The quality factors are both 38deg/dB.By changing the relative dielectric constant of the liquid crystal in the E-plane phase shifter to replace the frequency change of the series fed frequency scanning array,the E-plane beam scanning of the array is realized;meanwhile,the H-plane beam scanning of the array is realized by using the H-plane phase shifter to feed four channels of 1 × 8 series fed array in parallel.In addition,a layered bias feed network is designed so that each phase shifter can be controlled by an independent bias signal with complementary influence.The proposed two-dimensional continuous scanning array can realize continuous beam scanning of 10°?38° and-10°?-38° in E plane and-30°?30° in H plane.Based on the principle of sequential rotation feeding and liquid crystal tuning,a dual circularly polarized reconfigurable array based on liquid crystal material is proposed.The proposed 4 × 4 array is divided into four groups of 2 × 2 subarrays according to the sequential rotation feeding technology.The excitation direction of each group of subarrays is rotated 90 degrees in turn.At the same time,four groups of liquid crystal phase shifters provide gradient phase with a difference of 90 degrees to realize circularly polarized wave.In addition,by changing the output phase of liquid crystal phase shifter,the phase gradient of the excitation antenna array can be switched between positive and negative 90 degrees,so as to realize circular polarization wave The maximum gain of left and right circular polarization is 10.4dBi,and the axial ratio beam width of circular polarization is 18 degrees.Finally,the dual circularly polarized array is extended by one-dimensional beam scanning,and the dual circularly polarized array and one-dimensional scanning are realized by using Butler multi beam feeding network.