Research On The Design Of Sparse Array For Direction Of Arrival Estimation

The direction of arrival(DOA)estimation is widely used in civil and military applications such as radar,remote sensing,and navigation.In the traditional method,to avoid angular ambiguity in direction finding,the element spacing of the physical array is set to not exceed the half wavelength of the incident signal.This setting results in a strong mutual coupling effect between the array sensors,and direction finding can only be performed on signals less than the number of sensors at the same time.With the application of virtual transformation technology,DOA estimation based on sparse linear array(non-uniform linear array)becomes possible.Through the virtual transformation of the data received by the array,the corresponding virtual array response can be obtained from the physical array response.The virtual array has more array elements,so it can perform direction finding on more signals.Since the spacing of the array elements and the array aperture become larger,and the mutual coupling effect becomes weaker,the direction-finding accuracy of the sparse array is higher.This thesis revolves around sparse array design,two types of sparse arrays are proposed with the goal of improving the degrees of freedom and reducing the mutual coupling effect.The specific work is summarized as follows:1.By analyzing and summarizing nested arrays and their derived arrays,an array model with a high degree of freedom and an array configuration conforming to this model are proposed.There are two main contributions.One is that the array model covers some nested-like array structures,and the virtual array,namely difference co-array(DCA),corresponding to one array that satisfies the model,is non-porous;The other is that derived arrays of the model enjoy higher degrees of freedom.By comparing the array configuration conforming to this model with 6 kinds of high-degree-of-freedom sparse arrays,the advantages of the proposed array are proved theoretically and experimentally.2.Considering the mutual coupling effect between array sensors,in the case of ensuring a high degree of freedom,a novel sparse array is proposed to reduce the mutual coupling effect.And by adjusting the priority of increasing the degree of freedom and weakening the mutual coupling,two implementation strategies are analyzed.Compared with the three popular weak mutual coupling arrays,both theoretical and numerical experiments demonstrate that,the proposed arrays outperform other contrasting arrays,in terms of array degrees of freedom,array mutual coupling effect,and DOA estimation accuracy.