Research On Beamforming Algorithm Of Wideband Phased Array Radar

Wideband phased array radar has the advantages of high resolution,strong object classification and recognition capabilities,strong anti-interference ability,high reliability and the ability to detect and track dense targets,so many countries of the world are stepping up to research on wideband phased array radar and expanding the applications.Wideband beamforming technology is one of the key technologies of the wideband phased array radar.Therefore,corresponding beamforming technology should be studied according to the characteristics of wideband signals.This thesis takes wideband phased array radar as the research object.Starting from constructing the wideband phased array signal model,the beamforming algorithms for wideband phased array radar are mainly studied.The main contents are as follows:1.A wideband beamforming method based on fractional delay filter is studied.Firstly,according to the characteristics of the wideband signals,constructing the wideband phased array signal model.Secondly,analyze the reason that why conventional method of narrowband beamforming technology can't be used directly in wideband phase array radar.In order to compensate the channel dispersed delay accurately,fractional delay filter can replace the phase shifter.Finally,a method is proposed based on fractional delay filter.2.Wideband beamforming based on sub-array level is studied.A beamforming method based on subarrays is proposed.This beamforming structure is combined with phase shifter within sub-array and fractional delayer between sub-arrays and verify the correctness of the method through simulation.In order to solve the problem of the high sidelobe level of the traditional wideband array radar subarray division method,the sidelobes are suppressed by adding window processing based on the method of regularly overlapping molecular arrays.Finally,simulation experiments show that the method have good performance on sidelobe suppression.3.Wideband adaptive beamforming algorithms including frequency domain adaptive beamforming algorithms and space-time adaptive beamforming algorithms are studied.The theory and simulation analysis of the two frequency domain beamforming algorithms including ISM and CSM algorithms are presented in this thesis respectively,and the performance of these two frequency domain beamforming algorithms in interference suppression is verified.Then introducing the therory of the conventional space-time beamforming algorithm and the performance of the algorithm is verified by simulation.Because of the pre-steering delay units in the conventional space-time beamformer may encounter different errors,this error may cause severe performance degradation,so a new method without pre-steering delay units is proposed.This new method achieves the purpose of adaptive beamforming by a serise of frequency constraints,and the simulation results show that the new method can achieve wide beamforming,and have the ability of interference suppression.4.Due to the LFM signals often used in wideband phased array radar,beamforming can be performed using stretch processing based on the characteristics of LFM signals.According to the difference of receiving architecture,three kinds of wideband beamforming methods are proposed.Considering the cost and complexity of the implemention,the simulation and analysis of the wideband beamforming method based on multi-mixing signal processing are focused on.Finally,beamforming using stretch processing on the sub-array level is also considered.