Direction-of-arrival (DOA) estimation in the presence of array signal coupling

Direction-of-arrival (DOA) estimation is an important function in array signal processing. Many DOA estimation algorithms have been proposed catering for different situations and accuracies requirements. Nevertheless, most of these algorithms were designed based on the assumption of using ideal array sensors such as antennas with no interaction between them. A very common type of DOA estimation algorithms are the high-resolution algorithms such as MUSIC and ESPRIT. However, it is well known that MUSIC and ESPRIT are very sensitive to the antenna mutual coupling, which is a common phenomenon in almost all types of antenna arrays. In the presence of antenna mutual coupling, the array manifold is distorted, leading to a degradation of the orthogonality between the signal and the noise subspaces. Consequently, the high-resolution characteristic as predicted by the ideal DOA algorithms is gone. In this talk, a new method is introduced to characterize the antenna mutual coupling effect so that it can be removed from the distorted array manifold. The new method introduces a new concept of “receiving mutual impedance” to characterize the antenna mutual coupling in receiving antenna arrays. The new method is shown to be easy for use in DOA estimation and is almost universally applicable to many types of DOA estimation algorithms. Typical DOA estimation examples will be used to demonstrate the effectiveness of the new method.