Research On Estimation Method Of Two-Dimensional DOA Based On Coprime Polarization Array

Direction of arrival(DOA)estimation,also known as direction finding,is an important technical branch in the field of modern signal processing,which is widely used in radar,sonar,radio communication,biomedicine and other aspects.Most of the traditional DOA estimation methods are based on single-polarization scalar array,which can only use the phase information contained in the electromagnetic wave signal arriving at the array,and the polarization characteristic information of the incident signal is blind.However,in the increasingly complex and harsh modern battlefield electromagnetic environment,the polarization sensitive array can describe the microstructure information of the incident electromagnetic wave signal in the form of a vector.It can not only perceive the spatial information of electromagnetic wave signal,but also extract the polarization information of the signal,with high signal resolution and better anti-interference ability.However,the traditional polarization sensitive array DOA estimation system is mostly based on uniform array,which has limitations in the aperture and degree of freedom expansion of the extended array and the estimation of underdetermined parameters.The proposed coprime array provides a way to solve these problems.Compared with the uniform array with the same number of physical elements,it has larger aperture,lower mutual coupling,and can be extended to the virtual array with more degrees of freedom.It realizes the high precision unambiguous DOA estimation with more than the number of physical elements.Therefore,this paper combined the strengths of the polarization array and the coprime array,and transferred the coprime array into the polarization array,dedicated to the study of the twodimensional DOA and polarization parameter estimation of the mutual prime polarization array,and considered filling the holes in the extended virtual array by optimizing the array form,so as to further improve the freedom of the coprime polarization array.The main research contents are as follows:In the first part,the problem of transplanting the mutual prime array to the polarization sensitive array is studied.A DOA and polarization parameter estimation algorithm based on Lshaped coprime polarization sensitive array is proposed.A three-orthogonal dipole compression signal receiving model of mutual prime array is established,and a virtual array with higher continuous degrees of freedom is constructed.In this algorithm,DOA and polarization parameters are separated,and an auto-covariance matrix without polarization parameters is constructed,which avoids the simultaneous estimation of multi-dimensional parameters and greatly reduces the amount of computation.At the same time,the algorithm reduces the order of two-dimensional DOA to one-dimensional space,and obtains two one-dimensional DOAs by sparse representation method.An angle pairing method based on Khatri-Rao product is proposed to solve the problem of two-angle pairing under the condition of degree of freedom expansion of the polarization sensitive array.On this basis,the polarization parameters of the signal are obtained by the least square method.Simulation results show the effectiveness of the proposed algorithm.In the second part,the optimization of the array form of the coprime polarization sensitive array is studied,and the DOA and polarization parameter estimation algorithm based on the improved moving three-parallel coprime polarization sensitive array is proposed.This part presents two improved designs of moving triparallel co-prime polarization sensitive arrays.The number of continuous holes in the virtual array constructed in the static state of the array is less than two.By using the thought of moving array to fill the holes in the virtual array,the virtual array with fully continuous virtual elements is obtained,and the degree of freedom of the array is greatly improved.At the same time,the DOA and the polarization parameter estimation are decoupled.Based on the DOA estimation of the spatial smoothing MUSIC algorithm,the polarization parameter estimation is obtained by combining the cross-covariance matrix of the electric field components of pairwise subarrays.The simulation results show that the proposed array design can obtain virtual arrays with higher degrees of freedom under the condition of the same physical elements and has higher direction finding accuracy.