Research And Design On Wide Angle Beam Scanning Lens Antenna

Having no shielding effect and simple feding system,lens antenna is widely used in many areas.In order to increase the action airspace,improving wide-angle beam scanning performance of lens antenna is necessary.Although Lunberg lens,Rotman lens and reconfigurable lens antennas are able to realize wide-angle beam scanning performance,each has its drawbacks.Passive flat lens,or millimeter-wave(MMW)dielectric lens have advantage in fabrication and low cost,but research in their wide-angle beam scanning performance is scarely seen in the published literature.With the help of optimization algorithm,research on wide-angle beam scanning performance of flat lens antenna and MMW dielectric lens antenna is carried out in the thesis.The designing efficiency of lens antenna is increased by means of improveing modeling method and releasing the degrees of freedom of lens.There are two main parts in this dissertation:1.Bring Differential Evolution(DE)algorithm into flat lens antenna design.The model of lens antenna is established according to the principle of array antenna,and the pattern template is designed for each scanning angle.According to the trend of phase distribution on the lens surface,the relative phase distribution design method is proposed,and the distribution law is used to reduce the solution space greatly and improve the efficiency.The contribution of the degrees such as the feeding angle,deflection angle and feed loci,etc.to the performance of the wide-angle scanning performance is discussed.The effectiveness of the design method is verified by simulation and fabrication.A 20×20-element passive flat lens antenna operating at 12 GHz with 23% 3dB gain bandwidth is realized.The maxmum gain is 27.24 dBi which corresponding to 42% aperture efficiency and maxmum gain loss is 2.35 dB across the scan coverage from-45° to 45°,and the the side lobe level(SLL)is suppressed well.2.The Particle Swarm Optimization(PSO)algorithm is introduced into MMW shaped dielectric lens design.By using the computing advantages of different simulation softwares,the relative distance representation or Bernstein polynomial representation are used to model the dielectric lens contour,which can improve the design efficiency.In this thesis,a nested optimization method is proposed.In the calculation of the lens antenna of each contour,the optimization of the distribution of the amplitude phase of the feed is embedded.A cylindrically shaped dielectric lens with 6 feeds working at 28 GHz was designed.The scan angle of the lens antenna can reach a maximum of 71° during feed array scanning.