Research On Wideband Array Digital Beamforming

Wideband digital array radar is an all-digital array antenna radar which uses wideband signal waveform and digital beamforming technology to transmit and receive signals.Compared with the traditional narrowband radar,wideband digital array radar has higher search efficiency,better adaptive zeroing and lower sidelobe level.However,the traditional beamforming method cannot be applied to wideband digital phased array radar,and these methods will cause problems such as the increase of the width of the main lobe and the mismatch of the array beam pointing.Therefore,in order to achieve broadband digital beamforming,this thesis introduces a method of wideband digital beamforming using channel equalization and fractional delay filters.The implementation algorithms of channel equalization and fractional delay as long as their comparison are discussed.This thesis first introduces the basic mathematical representation of wideband digital beamforming by analyzing the mathematical model of linear radar array and the principle of wideband digital array beamforming.Then,digital beamforming based on fractional delay is introduced,and the selection of digital delay scheme as well as the design structure of different digital delay filters are emphasized:windowed method,maximum flatness criterion and farrow structure.The optimal design method of fractional delay filter can be obtained by discussing the algorithms of different schemes and analyzing the simulation results.After completing the design of the fractional delay filter,this thesis introduces the discussion of the channel equalization technique.In order to avoid the inevitable phenomenon of channel mismatch,this thesis studies different channel equalization algorithms and adaptive equalization algorithms in the time domain and frequency domain and makes a comparison.At the same time,on the basis of the realization of the channel equalization,the influence of the selection of different reference channels on the channel equalization compensation is studied,and the conclusion has a certain effect on the practical engineering application.In this thesis,digital beamforming with wideband is solved theoretically and practically through simulation research and data analysis.Wideband digital phased array radar has a wide application prospect,so the research in this thesis has certain practical significance.