||The purpose of this study was to investigate the impact on beamformers caused by antenna array mutual coupling and receiver gain/phase unbalance. The first is to introduce the basic principle of beamformers based on ideal conditions, including how beamformers generate output beams after a phased-array system receives signals, and the effects of weight on beamformers. The next is to describe the effects of antenna array mutual coupling (coupled matrix) on beamformers, the algorithm of estimating mutual coupling matrix, and the calibration method for mutual coupling effects. Then to specify the effects of combination of receiver gain/phase (gain/phase matrix) unbalance with mutual coupling on beamformers, and the algorithm of the comprehensive effects of mutual coupling and receiver gain/phase unbalance. The last is to present self-developed algorithm which only requires one calibration source instead of many to estimate distortion matrix. The approach to this algorithm is to estimate gain/phase matrix, to derive a compensation matrix for receiver gain/phase unbalance, to estimate the coupled matrix, and then finally to implement mutual coupling calibration.|
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