DOA estimation algorithm for non-circular signal by a large-spacing array with auxiliary element

In this paper, a direction of arrival (DOA) estimation algorithm for non-circular signal by a large-spacing uniform array with an auxiliary element has been presented. The auxiliary element is placed away from the last element of the large-spacing uniform array. The spacing between arbitrary two elements of the whole array is not limited by the half-wavelength of the signal. Firstly, two initial signal subspaces corresponding to the large-spacing uniform array and two row vectors corresponding to the auxiliary element are obtained by eigenvalue decomposition (EVD) of the correlation matrix. The two row vectors are expanded into two virtual signal subspaces by using the two initial signal subspaces. Then, the relationship between the virtual signal subspaces and the initial signal subspaces are used to form a high-dimensional signal subspace corresponding to a uniform linear array with half-wavelength spacing. Finally, DOA estimation can be got by using the estimation of signal parameters via the rotational invariance techniques (ESPRIT) algorithm. Compared with the traditional ESPRIT algorithm and non-circular ESPRIT (NC-ESPRIT) algorithm based on a conventional uniform linear array, the proposed algorithm has higher accuracy for DOA estimation and stronger robustness to the mutual coupling.