Online Mutual Coupling Calibration Using a Signal Source at Unknown Location

The effect of mutual coupling among the antenna elements will degrade the performance of array signal processing methods, and hence, mutual coupling calibration has attracted many research interests. However, existing approaches to deal with this problem either require the angular information of the calibration source(s) or require computationally expensive procedures to determine the mutual coupling coefficients. To this end, we propose an efficient method to calibrate the mutual coupling with a single source at unknown location. In particular, by exploiting the fact that mutual coupling is inversely related to their separation and is negligible when they are separated by a few wavelengths and the mutual coupling matrix (MCM) of uniform linear array (ULA) can be approximated as a banded symmetric matrix, it is shown that both the signal direction-of-arrival (DOA) and mutual coupling coefficients can be estimated in closed-form without any spectral grid search. Simulation results indicate that the proposed methods is able to provide promising performance compared with existing approaches.