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MMA Memo #110

Homologous Offset Antenna Concept for the Millimeter Array Project

Jingquan Cheng [1]

March 22, 1994

Keywords: antennas, off-axis antenna

A major obstacle in meeting the requirements for the MMA antennas is the gravitationally induced deformations. A new antenna configuration, consisting of an offset reflector combined with a slant axis mounting, has been investigated. With this combination the varying gravitational component is never perpendicular to the awntenna surface. This results in gravitational deformations that are substantially smaller than either a conventional antenna or a symmetric slant axis antenna. A preliminary design of an 8-meter offset slant axis antenna produces gravitationally induced deviations from the best fit parabaloid of less than 8 microns in all orientations. Although the major consideration in developing this concept has been the minimization of gravitational deflections, the design has other substantial advantages, such as greatly reduced blockage and much improved receiver access with reduced (or no) receiver movement as the antenna tracks.

[1] NRAO/TUC

Last modified: 09 December, 1999

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