Robust calibration of mutual coupling effect for a Uniform Circular Array

As for a compact Uniform Circular Array (UCA), the performance of Beam forming (BF) or Direction-of-Arrival (DOA) estimation will be severely degraded by strong electromagnetic mutual coupling effect, and the calibration method based on Rank Reduction (RARE) lacks robustness. Based on the special circular symmetry of a UCA, a new efficient and robust method is proposed to calibrate the mutual coupling effect in this paper. Only one single signal source and one trial are necessary to complete the calibration, and the direction of the signal source does not need to be calibrated beforehand. First, in discrete Fourier transform (DFT) beamspace, the mutual coupling matrix (MCM) is transformed to be a centro-symmetric vector, and then in a prior 2D spatial angular domain, limited angular search is conducted to get the estimate of the parameters according to a novel objection function based on the symmetry. Simulation results verify the effectiveness and robustness of the new method.