Research On Structure Optimization Design Of Non-Uniform Sparse Arrays

Direction of arrival(DOA)estimation is a main research content in the field of array signal processing,and the array structure has an important influence on the accuracy of DOA estimation.The spacing between adjacent array elements of the traditional uniform array is specified to be no more than half a wavelength.The number of estimable sources for DOA estimation using a uniform array is limited by the total number of elements,and there is a serious mutual coupling effect between densely arranged array elements.In order to solve these problems,non-uniform sparse array has received extensive attention due to its sparse and flexible array structure.Compared with uniform array,it has the advantages of large array aperture,high degree of freedom and good DOA estimation performance.In the thesis,the optimization design of the structure of non-uniform sparse arrays is the main research content.Several non-uniform sparse arrays with superior performance are designed for DOA estimation in different application scenarios.The principal details and novelty of thhesis can be seen as:(1)A new one-dimensional non-uniform sparse array is designed.For the sake of deal with the issue of low degree of freedom of the existing coprime one-dimensional array,an improved displaced coprime array is constructed by introducing a displacement of appropriate distance between two subarrays of the traditional coprime array and flipping one of the subarrays.The influence of array parameters on array properties is analyzed and proved,and the optimized structure of array Configuration is given,which achieves higher degrees of freedom and better one-dimensional DOA estimation performance.(2)A new two-dimensional non-uniform sparse array is designed.The displaced coprime array is extended to two-dimensional space,symmetric displaced coprime planar array is constructed by introducing a certain horizontal and vertical displacement between two subarrays of traditional coprime planar array.The influence of the shift distance on the continuity of the difference coarray is analyzed.It is proved that the optimal configuration of the symmetric displaced coprime planar array has improved the degree of freedom and the ability to resist mutual coupling compared with the existing array structure,and achieves higher precision two-dimensional DOA estimation in the mutual coupling environment.(3)Three new two-dimensional non-uniform sparse array based on moving platform are designed.The passive synthetic aperture technique is applied to the DOA estimation of non-uniform sparse array.The influence of the motion path of the platform and the structure of the sparse array on the synthetic difference coarray is analyzed.The motion path of the platform suitable for practical application scenarios is given.The array structure is optimized from two aspects:improving the degree of freedom and weakening the mutual coupling effect between the array elements.It is verified that the proposed array in the motion scene can improve the DOA estimation accuracy in both mutual coupling and non-mutual coupling environments.