Fourth-order cumulant based direction finding algorithm for non-circular signals using uniform circular array with mutual coupling

Uniform circular array has been widely used in direction finding systems due to its full azimuth and elevation coverage. However, the direction finding performance may degrade substantially in the presence of mutual coupling. Therefore, in this paper, we propose a direction finding algorithm for non-circular signals using uniform circular array under unknown mutual coupling. Based on the principle of rank reduction, the algorithm utilizes fourth order cumulant to decompose the multidimensional optimization problem into a one dimensional spectral search procedure. Without any multidimensional nonlinear search nor iterative computation, the algorithm can reduce the computational complexity effectively. Moreover, by constructing an extended fourth order cumulate matrix composed of circular covariance matrix and ellipse covariance matrix, the non-circularity of the sources has been fully utilized to improve the direction of arrival (DOA) estimation performance. According to the simulation results, the DOA estimation performance of the proposed algorithm outperforms the traditional fourth order cumulate based algorithm.