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ALMA MEMO #479
Requirements for Subreflector and Feed
Positioning for ALMA Antennas
Bryan J. Butler
National Radio Astronomy
Observatory
2003-12-08
This memo presents some calculations
related to requirements on subreflector and feed positioning for the ALMA
antennas. In order to keep gain loss at less than 1%, the axial (vertical)
positioning error in the subreflector should be less than about 0.09 λ, and in
the feed should be less than about 0.9 λ. The lateral positioning error for the
subreflector should be less than about 0.45 λ, and for the feed should be less
than about 10 λ. The rotational (tilt) error of the subreflector should be less
than about 5.5 λmm arcminutes if the rotation is about the vertex of the
subreflector.
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pdf version of ALMA Memo #479.
Last modified: 2004-01-07
alma-memos@nrao.edu