Research On Sparse Array Synthesis And DOA Estimation Algorithm

Antenna array technology has been widely investigated and applied in modern radar and wireless communication systems.In pratical engineering applications,in order to reduce the cost and complexity of systems,antenna arrays are designed in a sparse fashion.Studies have shown that by optimizing the element position and excitation,the sparse array has a narrower main lobe and a lower sidelobe level compared with uniform array with the same number of array elements.This thesis focus on sparse array synthesis and research on DOA estimation algorithm:Firstly,the synthesis of sparse array based on compressive sensing is studied,and a sparse array synthesis method based on orthogonal matching pursuit is proposed.In order to impose the minimum inter-element constraint,a preconditioned look ahead orthogonal matching pursuit that satisfies the precondition is proposed.It's shown that the proposed method can achieve 30%reduction of antennas with the minimum inter-element spacing greater than half-wavelength.In addition,a reweighted7)₁-based convex optimization method is used for pattern design,this method can use the minimal antennas to design a beam pattern that meets the desired criteria?mainlobe direction,beamwidth,low sidelobe?.Secondly,virtual array transformation from sparse array by means of array interpolation was studied and minimax optimization method was used to optimize the pattern of virtual array.Then,Two kinds of DOA estimation algorithms based on virtual array–spatial smoothing and root-MUSIC are studied,and the problem of decoherence for coherent signals was well resolved.The DOA estimation performance of virtual array,sparse array and uniform array with the same number of elements is compared.It's shown that the virtual array has lower estimation error and higher resolution probability.Finally,the MIMO radar transmit and receive array configuration is studied.Compared with the uniform array with the same number of array elements,effective array configuration can effectively increase the virtual array aperture by forming virtual array elements,which can improve the parameter estimation performance and increase the number of detectable targets.Based on the MIMO virtual array signal model,the spatial spectrum algorithm and compressive sensing are applied to MIMO radar DOA estimation.The results show that the DOA estimation based on compressive sensing for MIMO radar can achieve better resolution.