Researching Aerospace Targets Beamforming Based On Array Antenna

Array signal proeessing used for aerospace targets is a important branch of the modern signalprocessing，and its applications include radar，communieation，sonar,radio astronomy and so on..DOAhas been widely developed over the past more than thirty years. In real environments，the scenario ofmultipath propagation is very common due to various reflective surfaces，such as clouds，hills，buildings and some other manmade interferenee.Therefore,there are more and more researchersengage in the topic of DOA estimation，and hope to obtain more information to be direetly used bymilitary or civilian.. In digital beamforming algorithm, the non-blind adaptive algorithm are usuallyneed to know the prior information signal, however, reference signal transmission need to take certainbandwidth. Especially in satellite communications, launch the independent training sequence for eachreceiving end, takes a high price. It is undesirable undoubtedly now, because spectrum resourcesincreasingly nervous. In this case, the blind adaptive beamforming arises at the historic moment,itdoes not need reference signal, but use of the signal characteristics of itself to realize beamforming.This dissertation researched digital beam forming which is the core of antenna array surroundingaerospace targets,aims to put forward some improvement DOA estimation algorithm used foraerospace targets, the paper puts forward a new blind beamforming algorithm used for aerospacetargets at last. Some research work is as follows:Firstly, researched the concept of array antenna.Researched the common array structures and theadvantages and disadvantages of various array structures in the array signal processing.Hermitian andToeplitz matrix and their properties and the knowledge of eigenvalue decomposition are researchedtoo.Secondly, researched the traditional DOA estimation algorithm and super resolution DOAestimation algorithm used for aerospace targets.Put forward some improvement DOA estimationalgorithm based on the MUSCI algorithm and ESPRIT algorithm, and show the performance of thealgorithm through the simulation experiments. Studies have shown that super resolution DOAestimation algorithm can overcome the Rayleigh limit constraints, to achieve the separation of thesignal source.Thirdly, researched DOA estimation in the presence of multipath used for aerospace targets. Dueto multipath transmission and the effect of human disturbance, sometimes the array will receivecoherent signal from different direction. So this dissertation gives improved MUSCI algorithm andimproved ESPRTI algorithm for multipath transmission based on the classical algorithm. The improved algorithms are also effective for the relevant signal.Fourth, introduced Optimal Weight rules to describe the DBF and adaptive weighting coefficientadaptive algorithm used for aerospace targets, and compared the several adaptive algorithms. Studieshave shown that the convergence rate of RLS algorithm compared with the DMI algorithm is slower,but much faster compared with the LMS algorithm, RLS algorithm performance is close to the DMIalgorithm, so the advantages of the LMS algorithm and DMI algorithms are able to reflect on the RLSalgorithm.Fifth,presented a new blind beamforming algorithm used for aerospace targets.Based on thestudy of Dolph-Chebyshev weighting method, this dissertation presented a blind beamformingalgorithm used for aerospace targets combination of subspace technology.This method is suitable formultiple beam forming, and the algorithm is not only applicable to the line, and is also suitable forplanar array.