Abstract: An improved calibration method for a satelliteborne digital beanforming (DBF) receiving antenna is presented based on the signal subspace principle. On the basis of the fact that the mutual coupling effect of array is mainly determined by the distance between the array elements, the mutual coupling model is simplified by utilizing the symmetrical array distribution. Mutual coupling effect and imbalance among the ratio frequency (RF) channels are converted to amplitude and phase errors. Computational complexity of the subspace algorithm is reduced by adding specific array phase differences to the baseband. Computer simulation based on a 7element planar hexagonal antenna array illustrates the validity of the method. The performance of the algorithm is contrasted under different signal noise ratio (SNR) conditions and thus leads to the conclusion that the antenna error estimation precision can be improved by increasing the signal transmitting power. Simulation results show that the proposed method is of value for engineering application in satellite communication systems.

Key words: digital beamforming, mutual coupling, channel imbalance, antenna array, signal subspace, computational complexity, satellite communication systems