Novel Calibration of Adaptive Antennas

Kurzfassung

Due to their capability of mitigating interfering signals in spatial domain, the adaptive antenna arrays with digital beamforming are a promising solution for radio frequency interference and multipath problems faced by the receivers of Global Satellite Navigation Systems (GNSS). A special care should be taken of the carrier phase rotations and the group delays of the received GNSS signals which are introduced by the adaptive array during the beamforming process. In the paper a simple mathematical model for the calculation of the carrier- and code-biases on the corresponding pseudo-range measurements is proposed. A precise calibration of the antenna and RF front end hardware is prerequisite for the usage of the model in practice. A novel practical approach for such a calibration in the online mode is proposed and shown to be work well in an experimental GNSS array receiving system. Results of field tests for beamforming and direction of arrival estimation are presented. The antenna induced errors on pseudorange and positioning domains are estimated by using the array weights recorded during the tests and the proposed mathematical model.