Direction-of-arrival estimation for closely coupled dipoles using embedded pattern diversity

Direction-of-arrival (DOA) estimation for very closely spaced dipoles (no larger than 0.1 wavelength) is considered. In contrast to reducing the mutual coupling effect in conventional DOA methods, we demonstrate in this work that the mutual coupling can produce amplitude and phase difference of embedded element patterns, which can be utilized to greatly improve DOA estimation performance by incorporating the pattern diversity into the estimation algorithm. Simulation results show that two coupled dipoles achieve much higher DOA estimation accuracy than the ones without mutual coupling (for example, with the basic multiple signal classification (MUSIC) algorithm, the two coupled dipoles can achieve the root-mean-squared error (RMSE) of 1° within 120° arriving angle range for the spacing of 0.1 wavelength and RMSE of 2° within 90° range for only 0.02 wavelength, at moderately high SNR and sampling condition).