2007-11-13
We have designed the central cone for the subreflector of the ACA 7-m antenna. The cone is curved-shape and 53 mm in diameter, which is the maximum size to the extent that the cone does not affect the efficiency of the antenna even at the highest frequency of ALMA, 950 GHz. We have also optimized the profile parameters of the cone in consideration of off-axis feeds, especially for the lower frequency bands, so that the electric field reflected by the subreflector will be well suppressed within a radius of the vertex hole on the Cassegrain focal plane.
View a pdf version of ALMA Memo #574.
alma-memos@nrao.edu