2-D direction-of-arrival estimation in the presence of mutual coupling by exploiting the symmetry in a uniform circular array

Estimating the directions-of-arrival (DOA) of plane waves that impinge on an antenna array is an important issue in mobile communication systems. Because of their symmetry uniform circular arrays are attractive array configurations in the context of DOA estimation. In realistic antenna arrays mutual coupling between the antenna elements influences the electromagnetic characteristics of the antenna elements and affects the reliability and accuracy of the developed algorithms. We propose a 2-D DOA estimation algorithm that incorporates mutual coupling in full detail. Although mutual coupling complicates the receiving characteristics of an antenna array, the circular symmetry is still obtained in the presence of mutual coupling and a phase mode expansion of the array manifold is still possible. This enables us to apply UCA-RARE to estimate the azimuth angles independent from the elevation angles. Next, for each azimuth angle we perform a new search-free rooting algorithm, which provides the elevation estimate, based on the expansion of the array manifold into a double Fourier series.