Research And Design Of Reconfigurable Antenna Based On Liquid Crystal Material

In recent years,due to its important property of dielectric anisotropy,liquid crystal materials have been widely used in microwave applications as tunable devices.Compared with conventional microwave tunable devices,microwave devices based on liquid crystal materials are not only adjustable,but also can reduce costs and achieve integration.Therefore,this paper mainly studies the application of liquid crystal materials in reconfigurable antennas and offers new methods and new ideas for the design of reconfigurable antennas.The key content is summarized as follows:Firstly,two radiation pattern reconfigurable antennas based on the orientation of liquid crystal materials are designed,which achieves that the maximum radiation direction of the unit antenna is adjustable and the shape of the radiation pattern is variable.The first microstrip leaky wave antenna fills the liquid crystal with a single piece directly under the radiation patch of the microstrip leaky wave antenna.By loading different voltages at both ends of the liquid crystal,the maximum radiation direction of the unit antenna can be adjusted.The second microstrip leaky-wave antenna divides the liquid crystal filled directly below the radiation patch into two parts and performs block control.The applied voltage applied to each part is different,and the corresponding dielectric constant is also different.The shape of the unit antenna pattern can be switched between several different shapes.Secondly,a frequency reconfigurable antenna based on liquid crystal material was designed to achieve operating frequency adjustable.In combination with the working principle and characteristics of the microstrip antenna,liquid crystal is filled under the radiation patch of the microstrip antenna instead of the common dielectric substrate.By changing the electric field load on the two ends of the liquid crystal,the dielectric constant of the liquid crystal will also change along with it.It is the change of the working frequency of the liquid crystal microstrip antenna that eventually realizes the frequency reconfigurability of the antenna.Thirdly,a polarizable reconfigurable antenna based on liquid crystal material is designed to achieve the change of antenna polarization from circular polarization to linear polarization.Combined with the working principle of the antenna,the liquid crystal is filled in a feed network that achieves a phase difference of 90 degrees,and the feed network is rationally designed.An antenna that is initially polarized in a circular polarization is designed.When the applied voltage at both ends of the liquid crystal changes,the antenna The initial phase difference in the feeder network will also change.Eventually,the polarization of the antenna can be reconfigured.Fourthly,on the basis of many experiments,we discussed the orientation process,package design,offset design and other issues in the implementation of reconfigurable antennas based on liquid crystal materials,and summarized some concerns in practical design to improve the tuning capability and stability of the antenna.At the same time,in the specific design process,in order to design a liquid crystal antenna with good performance,it is need to predict in advance the dielectric constant of liquid crystal material.Thus,the test method for the dielectric constant of liquid crystal materials is also used and introduced in this paper.The liquid crystal material has been tested for dielectric constants and is ready for the specific design of the antenna.Fifthly,the test method of the dielectric constant of the liquid crystal material is introduced,and the dielectric constant of the liquid crystal material used in this paper is tested.