Research On Terahertz Array Antenna Technology Based On Liquid Crystal Material

With the rapid development of low earth orbit communication satellites,much high requirements are put forward for the bandwidth and capacity of inter satellite links.Terahertz has the characteristics of low photon radiation energy and rich spectrum information,which can provide communication with super large capacity.However,most materials lack good electromagnetic response in terahertz band,which leads to the problems of large volume,heavy weight and less functions of existing terahertz devices,and further makes the progress of terahertz devices and applications very difficult.The anisotropy of liquid crystal covers a wide frequency range from ultraviolet to microwave,the dielectric loss of liquid crystal decreases with the increase of frequency,and the dielectric properties are stable and the tuning rate is high in terahertz.Liquid crystal materials have shown great potential to actively modulate electromagnetic waves in a wide frequency range including terahertz band.Based on the actual scenario of inter satellite link,this thesis provides a feasible and stable antenna subsystem for communication satellite network,and carries out the research on terahertz electrically tunable array antenna technology around liquid crystal materials.The main work of this thesis is summarized as follows:1.The test scheme of dielectric characteristics in terahertz band and free space method are described.In order to explore the dielectric properties of liquid crystal in terahertz,the frequency selective surface which cascads square ring groove and circular hole is designed.The feasibility of testing the dielectric properties of liquid crystal in terahertz is verified by simulation.2.The principle and performance index of array antenna are analyzed.For planar reflective array antenna,an element phase compensation method is proposed.According to horn feed antenna,the 220GHz-325 GHz horn feed antenna is designed.Based on the tuning mechanism of liquid crystal,a three ring multi resonant terahertz reflection unit is designed.At 296 GHz,the phase shift can reach more than 360°,and the linearity is good.Through array simulation,a 10×10 terahertz three ring reflection array based on liquid crystal can achieve a maximum gain of 20.6d Bi and a scanning angle of ±30°.3.The 1×4 linear phased array antenna structure is studied.Firstly,a terahertz multimode interference power divider is designed based on self imaging effect.Then,a terahertz dielectric phase shifter based on liquid crystal working in W-band is processed and tested.Its phase shift reaches 300°,and the linearity is good.Finally,the 1×4 terahertz phased array antenna based on the dielectric rod antenna is built,which can achieve the maximum gain of 9.2d Bi and a scanning angle of ±10°.