Symmetric flipped nested array for mixed near‐field and far‐field non‐circular source localisation

Abstract

As it is known, existing mixed near-field and far-field non-circular source localisation rely on the uniform linear array (ULA). Compared with the ULA, the sparse array can obtain more consecutive lags and a larger physical array aperture. So a novel symmetric flipped nested array (SFNA) is proposed for mixed near-field and far-field non-circular source localisation. At the same time, according to the special geometry of the array, the non-circular phase information can be removed and the existing algorithm can be used to solve the problem of sparse array estimating the mixed near-field and far-field non-circular signals. First, by exchanging the positions of the subarrays in the traditional nested array and then flipping them, a new SFNA is formed; second, the authors present the maximum consecutive lags and composition method of SFNA. For example, 4MN +4M −3 consecutive lags can be obtained by using a 2M + 2N −1 array element; third, in the estimation of mixed near-field and far-field non-circular sources, a special cumulant is used to eliminate the range of the mixed near-field and far-field non-circular sources and a one-dimensional (1-D) spectral search is used to obtain all the directions of arrival, and the range can be obtained by defining the range spectrum; finally, numerical simulation results demonstrate the superiority of the proposed array.