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6 August 2010 Path length errors of VLBI antennas
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The performance of single dish radio antennas or telescopes is depending on the surface accuracy of the reflectors in the beam path and the focus/pointing errors induced by deviations/misalignment of the reflectors from a desired direction. For multiple dish VLBI arrays an additional mechanical effect, the path length stability, is a further source of performance degradation. For application at higher frequencies environmental influences as wind and temperature have to be considered additionally to the usually required manufacturing and alignment accuracies. Active measurement ("metrology") of the antenna deformations and their compensation by "active optics" (AO) respectively "flexible body compensation" (FBC) are established methods. For the path length errors AO or FBC are up to now not established methods. The paper describes how to handle the path length errors and the related metrology analogues to the established methods used for surface and focus/pointing error corrections.
© (2010) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Hans J. Kaercher, Eberhard Sust, Peter Emde, and Jürgen Kühn "Path length errors of VLBI antennas", Proc. SPIE 7733, Ground-based and Airborne Telescopes III, 77333S (6 August 2010);


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