Research And Implementation Of Digital Beamforming Algorithm For Dome Array Antenna Based On Subarray Patc

Antenna beams are required for detection and tracking the entire upper hemispherical space in a great amount of radar and communication applications.Among antenna array design schemes,beams generated by dome-shaped antenna array have the ability to scan in the hemispherical space with constant antenna gains and its such advantage has attracted further attention from people.As a type of conformal array antenna,dome array radar antenna is different from traditional planar array antennas in beamforming,beam scanning,beam tracking,etc.Dome array radar antenna is currently a research hotspot in the field of conformal antenna arrays.Based on a specific dome digital array radar project,this thesis carries out a series of work in method research,software implementation,hardware implementation,and experimental verification of pattern synthesis in the area of the dome-shaped antenna array,large-scale airspace search,tracking,and DBF,etc.The main research work and innovations of this thesis are presented as follows:(1)A simultaneous multi-beam scanning method scanning hemispherical airspace that applies in a sub-array-based dome array antenna is proposed.In a dome phased antenna array based on the semi-hexagonal patch array,using a large-angle front sliding plus small-angle array scanning to realize multi-beam scanning in the hemispherical space simultaneously can be realized.Based on digital beamforming technology using sub-array,the method of selecting the surface patch and the phase matching method of beam scanning in small angles during the sliding process of the array are respectively given.The simulation and calculation results would verify the preciseness of the design.(2)Aiming at the problem of the high sidelobe level of using traditional phase matching methods in the dome array,the alternate projection pattern synthesis method is researched to optimize and control the sidelobe level of the sum beam pattern of part of the selected array.Using this method,the maximum scanning range of the beams generated by the selected sub-array antenna patches can be expanded.Meanwhile,the complexity of sub-array resource scheduling is reduced when the antenna beam is scanning or tracking in a large space.The simulation and calculation results would verify the preciseness of the design.(3)Aiming at the general requirements of dome array radar based on sub-array digital beamforming technology,two-stage digital beamforming(DBF)processing scheme is proposed,and an intermediate frequency sampling and digital beam preprocessing module based on Software Defined Radio technology is designed.The FPGA software framework,including functional modules such as digital sampling signal recovery,software radio,first-level beamforming,and high-speed data transmission and reception has completed the design,programming,debugging and testing.With the help of the echo signal generated by the hardware target radio frequency simulator and the environment of the microwave anechoic chamber to test the main beam performance of receiving and transmitting pattern of the dome array antenna,the joint debugging of the whole radar was successful.Actual test results verify the accuracy of the beamforming algorithm and program design.