In-Orbit Analysis of Antenna Pattern Anomalies of GNSS Satellites

Kurzfassung

The payload of a typical navigation satellite encounters heavy strains during launch. This indicates the need to characterize and assess the antenna and consequently the total signal performance of a satellite in orbit. Using ground measurements with a high gain antenna seems to be a powerful basis for this analysis. This paper introduces the used measurement facility and strategies for obtaining a sufficient amount of measurement data based on the used simplified satellite attitude and yaw steering model. The analysis algorithms will be described in detail and as a side product itwill be shown that transmitter power variations of the navigation satellite over time can be characterized and separated from the pure influence of the satellite antenna. The last section presents the exemplary antenna pattern characterization for the second Galileo test satellite GIOVE-B (Galileo In-Orbit Validation Element) based on calibrated flux density measurements taken with DLR’s 30 m high gain antenna for the E1 frequency band.