Research On Staring Beamforming In Spaceborne Phased Array

With the introduction of 5G and even the development of 6G,user traffic has increased significantly in the Internet era,and broadband satellite communications have gradually been combined with terrestrial networks,which results that communications networks form a development trend toward space-ground integrated network.In order to improve the throughput of satellite nodes,the use of spectrum resources based on Ka and above frequency bands and the researc h of multi-beam technology gradually become the new focus.Low-orbit satellites play an important role in the space-earth integrated network.Compared with mid-to-high orbit satellites,low-orbit characteristics make it difficult for traditional fixed beam solutions to exert better technical effects.However,staring beams can be flexibly changed by changing the beam direction.The characteristic of realizing the continuous service of a single beam to the target area has great application potential and has received widespread attention.First of all,this article first studies the beamforming algorithm of staring beams,introduces several beamforming algorithms commonly used in engineering,and analyzes the characteristics of each algorithm.Later,in view of the application background of large-scale arrays and the beamforming problems of transmitting arrays,the fast beamforming technology based on Iterative Fourier Algorithm is studied under the condition of uniform phased arrays,and the projected subsets are designed to achieve a new fast and flexible beamforming algorithm.After that,according to the two factors of the number of array elements and the number of beam sampling points in the algorithm,this article evaluates the influence of different values on the performance of the algorithm through simulation experiments.On this basis,the performance of the algorithm is tested under the sudden failure of some elements in the array,and finally the ability of the algorithm in the synthesis of spot beams and shaped beams is shown.The simulation results show that the algorithm has strong flexibility and efficiency.Then,this article studies the method of estimating the position of the satellite to the ground target during the staring.Aiming at the problem that the user cannot maintain the uplink connection with the satellite in the actual communication process,a method of actively estimating the position of the ground target on the satellite is proposed.The estimation method effectively avoids the problem of the satellite's inability to know the position caused by the difference in upstream and downstream traffic.On this basis,this article studies the changing laws of the elevation angle and azimuth angle when the satellite and the ground target move relative to each other,and further discusses the causes and effects of the angle estimation error.Finally,this article applies the two algorithms described in the multi-beam staring system.First,the path loss problem of the spot beam model is analyzed.On this basis,in view of the problem of beam broadening in phased array electronic scanning technology at large off-axis angles,this paper uses the proposed Iterative Fourier algorithm combined with template beams to construct low-sidelobe beam pattern.And the spot beam gain was verified by simulation and the influence of main lobe division,side lobe limitation and template design on the result was discussed.At the end of the article,a simulation experiment of multi-beam staring is carried out based on the beamforming algorithm and azimuth estimation method described in this article.The results show that the technology described in this article can realize multi-beam staring,which has potential application value for systems with beam coverage planning.