The Group Delay Calibration of the Standard Antenna and the Group Delay Measurement of the Beidou Airborne Antenna

The antenna group delay (GD) is an important component of the total GD of the satellite navigation and positioning system, and its measurement accuracy will directly affect the positioning accuracy of the system. The Radio Technical Commission for Aeronautics (RTCA) specified the GD measurement method and limit of the GNSS airborne active antenna explicitly in its technical standard DO-301. In this paper, an antenna GD calibration method based on space scan is proposed, which can eliminate the GD measurement error caused by the multiple reflections between antennas during the calibration process, and as a result the high precision GD calibration of the standard antenna is achieved with an extended uncertainty only 0.14 ns (k = 2). Then, the GD of a certain type of domestic Beidou airborne antenna is measured using the standard antenna whose GD is precisely calibrated using the proposed method. The measurement frequency range is 1561.098 MHz ± 2.5 MHz (B1I) and the results shows that the maximum deviation of the GD (Δτ) is 7.43 ns consistent with the requirement of the standard DO-301. The proposed method in this paper enhanced the GD calibration accuracy of the standard antenna, so using this kind of calibrated standard antenna to measure the GD of the Beidou airborne antenna, the accuracy and reliability of the measurement results can be guaranteed.