GPS Block II/IIA Satellite Antenna Testing using the Automated Absolute Field Calibration with Robot

Gerhard Wubbena, Martin Schmitz, Gerry Mader, and Frank Czopek

Abstract:	The characteristics of the GPS satellite antenna has an important impact on precise GPS positioning. The transition from relative phase center offsets and variations (PCV) to absolute PCV for the receiving antennas on the ground requires PCV for the satellite antennas. Currently, the IGS is estimating elevation dependent PCV pattern from global networks and from the ionospheric free linear combination. Absolute PCV field calibration for GPS receiver antennas has been available since 2000. The methodology was developed by Geo++ in cooperation with the Institut für Erdmessung, Universität Hannover starting in 1996. The absolute field calibration provides absolute phase variations of GNSS antennas completely independent from any reference antenna or station dependent effects. In 2000 NGS attempted a relative PCV calibration on a BLOCK II/IIA antenna which was used as the qualification antenna. This antenna is identical to the flight antennas. Due to the complex design and small beam width results from this test produced limited results. In 2006 NGS approached the GPS wing who sponsored the shipment of the antenna to Geo++ where the absolute PCV measurement process would be used on the BLOCK II/IIA antenna. The PCV determination proved challenging due to the size of the antenna which caused modifications and redesigns of equipment and procedures use to determine the PCV. Testing was delayed by wet year in the Hanover region of Europe Experiences and results from the testing of the BLOCK II/IIA antenna are presented which cover elevation and azimuth dependent phase variation (including mean offsets).
Published in:	Proceedings of the 20th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2007) September 25 - 28, 2007 Fort Worth Convention Center Fort Worth, TX
Pages:	1236 - 1243
Cite this article:	Wubbena, Gerhard, Schmitz, Martin, Mader, Gerry, Czopek, Frank, "GPS Block II/IIA Satellite Antenna Testing using the Automated Absolute Field Calibration with Robot," Proceedings of the 20th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2007), Fort Worth, TX, September 2007, pp. 1236-1243.
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