Fast and Accurate Beam Direction Calibration Method for Phased Array Antennas Using PCA

Various methods have been proposed in the literature to calibrate the amplitudes and phases of phased array channels. However, physical factors—such as mutual coupling between antenna elements, quantization errors in phase shifters, and residual channel calibration inaccuracies—often interact to cause the actual beam direction to deviate from the designed angles. These deviations typically become more pronounced at larger scanning angles. Consequently, accurate beam direction calibration is critical for phased arrays employed in high-precision angle-of-arrival estimation. In this work, we propose a fast and accurate offline calibration method based on principal component analysis (PCA) for phased arrays whose channels have been calibrated. By extracting beam direction error features at a subset of angles and fitting their principal components, our method accurately predicts beam direction errors across all required angles. Experimental results show that, when measuring at only 1/22 of the angles, the three standard deviations (3σ) of the differences between predicted and measured beam directions remain below 0.25º for 12×12-element arrays within a ±25º range in both azimuth and elevation planes. Compared with typical interpolation methods, our approach substantially improves the efficiency of beam direction calibration and the underlying mechanisms are thoroughly analyzed.