Research On Beampattern Synthesis Algorithm For Array Radar

Array radar has been widely implemented and continuously researched because of its high detection performance and strong interference suppression ability.Array beampattern synthesis technology is an important branch in the research fields of array radar,which plays an important role in maintaining the high performances of array radar.In practical applications,array radar needs to solve different beampattern synthesis problems for different scenarios.On the one hand,it is expected to have high angle precision when array radar works in detecting mode,so that the large-scale antenna arrays are often implemented,which leads to high computational complexity of beampattern synthesis algorithm.Besides,the weightings with finite resolution are applied for array radar in the practical scenarios.On the other hand,both narrowband array radar and wideband array radar expect the mainlobe width of the beampattern to be as narrow as possible.In addition,to deal with the complex jamming environment,the synthesis of sidelobe on the wideband array radar beampattern should have strong flexibility.Focusing on the problems,which are high computational complexity,finite precision weighting,wide mainlobe width and sidelobe synthesis of wideband pattern with enough flexibility,in the applications of array radar in the above scenarios,this dissertation presents the synthesis algorithms such as low complexity,quantization weight,minimizing the mainlobe width and flexibly controlling the sidelobe of wideband pattern.The main work and contributions are summarized as follows:1.Low complexity beampattern synthesis via improved accurate controlTo solve the problem of high computational complexity in beampattern synthesis of large-scale antenna array,the two weight vectors in the single point accurate control algorithm based on Weight vector ORthogonal Decomposition(WORD)are firstly analyzed.Then,one of them is determined to be the ultimate solution,so as to omit the weight vector selection procedure,and thus the Improved WORD(I-WORD)algorithm is proposed.Then,on the basic of the single point I-WORD algorithm,the Multi-point control based on I-WORD(MI-WORD)is proposed by constructing a low complexity matrix to find the intersection of weight vectors.This MI-WORD algorithm achieves multi-point accurate array response control and has the advantage of low computational complexity.Especially,it is suitable for beampattern synthesis when the number of array antenna is large,for example,the jointing receive and transmit beampattern synthesis of Multiple-Input Multiple-Output(MIMO)radar.2.Beampattern synthesis with quantized weights for array radarTo find the weightings whose amplitudes and phases are quantized with finite resolution for synthesizing of array radar,an optimization problem considering the minimum deviation of quantization pattern as the objective function is established.To sovle this optimization problem,a novel jointing Multi-point control and Iterative Gradient Descent(MIGD)algorithm is proposed.In addition,the characteristics of beampattern synthesis for subarray radar are analyzed,and then the subarray level finite resolution weightings are obtained by MIGD algorithm.So,the beampattern synthesis algorithm based on quantization weights for subarray level radar is proposed.3.Wideband constant beamwidth synthesis with minimum mainlobe widthTo achieve minimum mainlobe width of wideband beampattern for array radar,a sparse optimization problem for single frequency beampattern with minimum mainlobe width is established by introducing a slack variable.A new sparse encourage function is firstly proposed to solve the sparse optimization problem.Then,the sparse optimization beampattern synthesis with Mimimum Mainlobe Width(MMW)algorithm is proposed.Besides,by determining the minimum width of wideband constant beamwidth with the MMW algorithm and realizing the wideband constant beamwidth with sidelobe level optimization,a wideband beampattern synthesis acheving Constant Beamwidth via MMW(CB-MMW)algorithm is developed.4.Wideband beampattern sidelobe synthesisTo achieve flexible and accurate sidelobe control of wideband beampattern for array radar,the weight vector constrcution form of Flexible Array Response Control via Oblique Projection(FARCOP)method which is suitable for single frequency beampattern is firstly analyzed.Then,the Modified FARCOP(MFARCOP)is proposed with low computational complexity.Further,the Wide Band MFARCOP(WB-MFARCOP)algorithm is obtained by achieving flexible and accurate sidelobe control utilizing the wideband space-frequency processing structure where the weights of each frequency subband are obtained by MFARCOP algorithm.