Research On Key Technologies Of Broadband Lens Antenna

Development of communication system makes improvement of antenna in beamforming application,high gain and wide band allimportant.Compared to the traditional phased array,lens antennas own advantages of beam-controlling capability and high gain.Meanwhile,lens antennas free from the feed-shade,have simple fabrication process,and the progress in technology also bring wider applications to lens antennas.In this thesis,the particle swarm optimization(PSO)algorithm is utilized to explore characteristics of the lens antenna such as field-controlling ability,lagre aperture and high gain.Consdering the narrow-band performance of lens antennas,the PSO algorithm is also utilized to ensure bandwidth when achieving specific targets.The work of this thesis mainly consists of two parts:In the first part,a rotation symmetry dielectric dome lens(DDL)with a phased array antenna(PAA)feed is proposed based on the PSO algorithm.The design of PAA-fed DDL is aimed at achieving cosecant squared radiation pattern in 26-29 GHz.In the first stage,after expanding the lens beam-scanning ability,preliminary optimization of the Comsol two-dimensional model is carried out.Then in the second stage,the optimization of the DDL in HFSS is completed,finally achieving the cosecant squared radiation pattern covering from 0° to 84°.The Vivaldi PAA(8×8)is designed,which can scan down to 60°in both E-plane and H-plane,to illuminate the DDL with the weighted excitation coefficients optimized by the PSO algorithm.Compared with the traditional single antenna such as horn and waveguide,the radiation energy is more concentrated by using PPA,and the rotation symmetry of feed patterns in the azimuth plane is non-essential.In the experiment,the whole PAA-fed DDL with cosecant squared pattern is measured and accurately evaluates the proposed design.In the second part,a wideband planar lens antenna with dual polarization and high gain is proposed.On account of working in terahertz band,a periodic element with dualresonant structure is utlized to reduce machining complexity and realize dual polarization.After structure optimization,the combination of square patch and square ring can satisfy the 0°-360° phase compensation in the whole working band.During the array design,the global arrangement using PSO algorithm and local optimization of the lens antenna are both considered.Finally,a planar lens antenna is designed,the maximunm gain is 30.9d Bi,the bandwidth of 1 d B gain drop is 13%,and the aperture efficiency at 160 GHz is48.6%.