The Design Of Circularly Polarized Multi-beam Antenna On Millimeter Wave

With the progress of the times,more and more requirements and challenges have been put forward to communication technology.We expect that communication system will have higher transmission rate,larger channel capacity,lower delay,higher stability and lower power consumption.However,traditional spectrum resources have been exhausted.Millimeter-wave band will be applied to next generation communication technology.However,millimeter-wave communication has the disadvantage of high loss and susceptibility to interference.The circularly polarized wave has excellent antijamming characteristics.And the multi-beam antenna can effectively improve the beam gain.Traditional microstrip transmission lines have a large loss interference in millimeterwave band,while metal waveguides are difficult to integrate.Substrate integrated waveguides(SIW)become one of the best transmission lines in millimeter-wave band,because it take into account both the advantages of low loss and integration.Beamforming network is an important means to realize multi-beam antenna.There are mature design schemes and ideas for beamforming network based on substrate integrated waveguide.In this paper,two schemes of millimeter-wave circularly polarized multi-beam antenna based on substrate integrated waveguide are designed and implemented,taking millimeter-wave circularly polarized multi-beam antenna as the research direction.The main contents of this paper include:The research background and significance of millimeter-wave circularly polarized multi-beam antenna are introduced.The research results of multi-beam system design,circularly polarized antenna and array design,circularly polarized multi-beam antenna design are summarized.The polarization of electromagnetic wave,the principle of beam scanning,and the control of beam polarization during beam scanning are analyzed theoretically.The design points of circularly polarized multi-beam antenna are summarized.The relationship between the axis ratio and the cross polarization level is deduced,and the comparison table between AR=0.5dB-4dB and the cross polarization level is given.A magneto-electric(ME)dipole antenna which can be applied to uniform linear arrays is designed.On the basis of 3×3 Butler matrix,a 5×6 Butler matrix which can retain normal beams is designed.The working principle of 5×6 Butler matrix and the design idea and process of each component are introduced in detail.A circular polarized five-beam antenna array with a gain of 12 dBi and a coverage of <40° is realized,fabricated and tested.A magneto-electric(ME)dipole antenna which can be applied to planar arrays is designed.The integrated cage cavity structure is introduced to make the antenna have a wider axial ratio beam-width.Then,a 2×2 magneto-electric dipole antenna array fed by rotating sequence is designed.Based on the 2×2 magneto-electric dipole antenna array,a miniaturized 4×4 Butler matrix for two-dimensional beam scanning is designed.A circularly polarized four-beam antenna array with two-dimensional scanning and gain of 10 dBi is fabricated and tested.