Research On Key Technologies Of Wideband Digital Array Radar

With the continious development of technologies of array radar and digitalization,digital array radar(DAR),particularly the narrowband DAR has been energetically developed and widely applied.As the further development of narrowband DAR,wideband DAR(WDAR)is the artistic achievement and inevitable trend of radar for it integrates the advantages of active phased array radar,digitized radar and wideband radar simultaneously.Based on the background of a WDAR test bed,the dissertation focuses on the development trend and system structure of WDAR,wideband digital beamforming(WDBF)in time domain,WDBF on subarray level,coherent wideband array signals processing by using coherent signal subspace method(CSSM).The contents are organized as follows:1.The development history and trend of WDAR and its corresponding technologies at home and aboard are introduced.The system structure of fully digitized WDAR and the functional characteristics of its subsystems are studied with its corresponding technologies briefly analized.2.Two WDBF methods in time domain which are relatively easily realized in engineering are presented.For the beamforming of WDAR must take aperture effect into consideration,through analyzing the prodedure and error of signal processing in WDBF in time domain,WDBF method based on integer delay at IF or RF and WDBF method based on fractional delay at baseband are studied.The effects of three frequently-used fractional filter design methods and array channel dismatch on the performance of WDBF method are also researched.3.The WDBF method in time domain based on accurate digital dealy at subarray level is studied as well as the influence of array partion on the method.4.Using CSSM to achieve the DOA estimation of coherent wideband array signals is studied in this part.Almost all traditional focusing algorithms need to previously estimate or assume DOAs to construct signal subspace,and the estimation error or assuming error inevitably generates hardly controlled focusing error which leads to the bias of final DOAs estimation.In the article through constructing a kind of signal subspace and reference focusing matrix which are independent on direction of signal,a new CSSM is proposed to realize focusing process without the prior information of signal direction.Theory analysis and computer simulations show that,compared with traditional CSSM,the proposed method has advantages in requiring no prior knowledge of the signal direction,computational cost and performance of DOAs estimation.