Collaboration in GNSS Antenna Calibration: Insights from the IGS Ring Calibration Campaign

Obtaining consistent phase center corrections (PCCs) for GNSS receivers remains a significant challenge, as there is currently a lack of benchmarks to  consistently evaluate patterns or comparable values between different calibration institutions and methods (anechoic chamber and field robots). To address this problem, a global collaboration with nine calibration institutions known as the IGS Ring Calibration Campaign (IGS ringCalVal) has been  launched. This comprehensive initiative aims to compare results from different calibration methods and create a robust framework for quality assessment. Six antennas from different manufacturers were used for calibration in this campaign.

Over the past year, significant progress has been  made. We have developed benchmarks and methods that facilitate the comparison of PCC patterns. Our detailed results show that in the pattern domain, the system/frequency consistency per antenna design varies within an uncertainty level of ±1 mm, with an additional elevation-dependent effect. In the positioning domain, system-specific PPP (Precise Point Positioning) results per antenna and GNSS system are presented, which show a deviation of typically less than 2-3 mm for the horizontal coordinate component and less than 5 mm for the vertical component between different systems. But also, special cases will be discussed. Finally, these results are crucial for establishing global standards for PCC calibration and verification
of receiver antennas.