| With the development of social informatization,there is an explosive growth of data exchange,which has put forward higher requirements for wireless communication.More and more application scenarios such as satellite communication,naval communication,etc.need antennas with high gain,multibeam,and low cost.Luneburg lens stands out among many multibeam solutions because of its multi-beam,wide angle beam scanning,high broadband,and high gain features.With the continuous development of 3D printing technology and effective media theory,the fabrication difficulty and manufacturing cost of Luneburg lenses have been greatly reduced.Therefore,this paper designs a high isolation dual circular polarization multibeam Luneburg lens antenna and a large frequency ratio shared aperture multibeam Luneburg lens antenna based on the3 D printed Luneburg lens.The content of this dissertation is summarized as follows:(1)Firstly,based on the conventional polarization grid bicircular polarization antenna,its working principle is analyzed and a broadband dual circularly polarized antenna operating in K/Ka band(18～32 GHz)is designed,and the experimental results are basically consistent with the simulation results.Based on the designed wideband dual circular polarization antenna,the port isolation of the antenna is improved by implanting two evanescent mode waveguide filters,and the port isolation is increased from 20 d B to 65 d B.Secondly,based on the effective media theory,a discrete layered,70 mm diameter spherical Luneburg lens is designed.Finally,a 5-beam multibeam antenna system is formed by using five highly isolated dual circularly polarized antennas with Luneburg lenses.After the measurement,five left-handed circularly polarized beams at 20 GHz with a gain of 20 d Bi were obtained,and five right-handed circularly polarized beams at 30 GHz with a gain of 23 d Bi were obtained.the beam coverage was ±40°.The antenna gain was increased by about 13 d Bi by adding the lens.(2)In order to realize the low cost and miniaturization of the communication system,a microwave/millimeter-wave shared-aperture multi-beam antenna system based on the Luneburg lens is designed.Firstly,the working principle and design process of the substrate integrated coaxial line(SICL)based low cross-polarization dipole in millimeter wave band,the design of 1.5times wavelength dipole in microwave band and the description of the shared aperture scheme are presented.The shared aperture antenna consists of 20 millimeter-wave dipoles based on SICL and3 microwave band dipoles integrated together,and the test results and simulation results are in general agreement.By loading the ideal Lombard lens,a beam of 20 is obtained at 28 GHz with a coverage range of ±84° and a gain of 32 d Bi per beam with a gain improvement of 26.5 d Bi.At 3.6GHz,a beam of 3 is obtained with a coverage range of ±35° and a gain of 15.5 d Bi with a gain improvement of 11 d Bi.Finally,a 200 mm diameter Luneburg lens and an experimental analysis of the shared aperture multibeam antenna was carried out. |
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