Research On Receiving Simultaneous Multi-beam Technology Of Digital Array

Multi-beam forming technology means that phased array radar can realize multiple independent beams through a single antenna aperture at the transmitting end or the receiving end.The application of this technology in phased array radar systems is receiving more and more attention.Traditional multi-beam forming networks are implemented in hardware by analog means.With the digitization of radar,the hardware structure can no longer meet the demand of digital radar for multi-beam technology,and digital multi-beam forming technology has become a research hotspot.In this paper,the technology of simultaneous multi-beam formation at the receiving end is studied around the two cases of narrowband and wideband signals received by digital arrays.The main research work is as follows:1.Based on the uniform linear array,the array signal models of the array receiving narrowband signals and wideband signals are introduced respectively,and the linear frequency modulation signals commonly used in radar arrays are described in detail.The principle of beamforming is expounded,and the characteristics and applicable scenarios of two types of beamforming algorithms based on data independence and self-adaptation are compared.Based on the beamforming,the principle of digital array accepting simultaneous multi-beam technology is introduced.2.When the array receives the narrowband signal,according to the classification of beamforming,two kinds of data independent multi-beamforming algorithms,such as conventional windowing and beam pattern synthesis,are discussed.Three adaptive multi-beamforming algorithms are also discussed.The performance,advantages and disadvantages of the five algorithms are compared by simulating their pattern and spectrogram.3.When the array receives the wideband signal,the four multi-beamforming algorithms of wideband signal based on space-frequency structure is studied.For conventional divided subbands,all subbands are beamformed using the minimum variance distortionless response(MVDR)algorithm.The simulation results show that the diagonal loading method improves its performance in practical applications,Meanwhile,The combination of focus and matrix reconstruction is better than diagonal loading.For the combination of focus and narrow-band beamforming algorithms based on second-order cones,the application of broadband data independent multi-beamforming algorithms is studied and simulated.4.The space-time structure commonly used for beamforming of wideband signals is studied,which shows that the space-time structure is more superior than the space-frequency structure.Three adaptive multi-beam algorithms based on space-time structure and a beam-pattern synthesis algorithm based on space-time structure are compared.The multi-beamforming algorithm based on norm boundary constraint uses the spatial response change function to achieve constant beamwidth.It is robust to the steering vector error.The wide-band constant beamwidth beam-pattern synthesis algorithm based on the second-order cone programming can simultaneously achieve constant mainlobe response and control sidelobes.