Spatial smoothing for direction of arrival estimation of coherent signals in the presence of unknown mutual coupling

There is rarely a method that can deal with the direction of arrival (DOA) estimation of coherent signals in the presence of unknown mutual coupling. Based on the special structure of mutual coupling matrix for uniform linear array (ULA), an improved spatial smoothing algorithm for DOA estimation of coherent signals is proposed. The DOAs can be accurately estimated without any calibration sources since the effects of mutual coupling can be eliminated by the inherent mechanism of the proposed algorithm. Simulation results demonstrate the effectiveness of the algorithm.