Real-valued DOA estimation for uniform linear array with unknown mutual coupling

In this paper, we propose a real-valued direction-of-arrival (DOA) estimation method for uniform linear arrays (ULAs) in the presence of unknown mutual coupling. By taking advantage of the special structure of the mutual coupling matrix for ULAs, the effect of mutual coupling is eliminated by the inherent mechanism of the proposed method. Moreover, the computational complexity is reduced by a factor of at least four after further performing a unitary transformation capable of converting a complex covariance matrix into a real one. We also investigate the performance loss due to the imperfect structure of the mutual coupling matrix under the NEC-2 code. Experimental results with respect to the NEC-2 code illustrate that our new method even outperforms a state-of-the-art method in the literature. (C) 2012 Elsevier B.V. All rights reserved.