Investigation Of Terahertz Liquid Crystal Electronically Controlled Scanning Antenna

Nowadays with the development of millimeter wave and terahertz microwave technology,the application of electric tuning devices made of liquid crystal materials has become more and more widespread.The methods of phase adjustment mainly inc lude mechanical drive,integrated circuit design and tunable materials.Among them,the liquid crystal material can realize stable adjustment of the dielectric constant of a wide frequency band in millimeter waves and even terahertz.The combination of the planar array and the liquid crystal electrical tuning characteristics can achieve the characteristics of miniaturization,low cost,low loss,high resolut ion,and high precision beam directivity in the millimeter wave band.In this paper,based on the birefringence characteristics of the liquid crystal material in the millimeter wave and terahertz frequency bands,the liquid crystal is combined with the plane reflection array and the plane transmission array to realize the directional scanning of the beam.In this paper,the simulation design of the reflective liquid crystal phase shifter is first carried out,the phase shift ing principle of the reflective liquid crystal phase shift ing unit and the parameters affecting the phase shift ing characteristics are studied,and the multi-dipole reflective liquid crystal phase shifter is designed;The polarization conversion characteristics of the circular-linear polarization converter in the millimeter wave band,the polarization converter array based on the frequency-selective surface structure working in the millimeter wave band is designed;finally the reflective liquid crystal electronically controlled scanning antenna and the circular-The combination of linear polarization converters,through analysis and simulation,achieves high gain control of circularly polarized beams,which greatly improves the application scenarios of liquid crystal electronically controlled scanning antennas.However,for the reflective liquid crystal electronically controlled scanning antenna,the horn feed and the radiating beam are in the same space,which forms an occlusion effect,which limits the scanning range of the beam.In order to solve this problem,this paper studies and designs a transmissive liquid crystal electronically controlled scanning antenna.Arrays can completely eliminate the effects of feed occlusion effects.The designed transmissive liquid crystal phase-shifting unit design combines a slot-coupled microstrip antenna structure,and the phase-shift ing is achieved by changing the dielectric constant of the liquid crystal through the bending feeder of the middle layer,and the thickness of the liquid crystal layer is compressed to 10 microns,which greatly improves the liquid crystal response Speed,successfully achieved a phase shift of more than 200 degrees,realized high-effic iency transmission on the simulation software,realized a beam scan of plus and minus 30 ° through space feeding,and finally introduced a mirror waveguide slot antenna with high gain characteristics The feed source realizes the combination with the transmissive liquid crystal electronically controlled scanning antenna,which significantly improves the oral surface utilization effic iency and gain,and successfully realizes a beam scan of plus or minus 45 degrees.