J. Cheng [1]
November 14, 1992
Keywords:
A slant axis antenna concept differs from a conventional antenna design in many aspects. The slant axis antenna involves a different coordinate system ans has a different structural arrangement. Compared with conventional antennas with similar backup structure supporting diameter, it may result a higher natural frequency telescope structure. This is important to allow switching rapidly from source to source. However, the slant axis antenna has a changeable force condition on its two main bearings, which is undesirable to its pointing performance. In this memo, the coordinate transformation formulas for slant axis antenna are worked out, the changeable force condition is analyzed and the effect of changeable force condition to the antenna pointing performance discussed. Its moment of inertia is compared with that of a conventional antenna for which the location of the elevation axis is similar to the location of the slant bearing. Ways of improving the structural performance of the slant axis antenna are discussed and different arrangements of offset version of slant axis antennas are provided. Finally the polarization and sweeping diameter problems of the slant axis antenna are also examined. For an antenna structure, the wind and temperature effects on the reflector surface and on the pointing accuracy are always serious issues. In this memo, this part of work is not included.
[1] NRAO/Tucson
Last modified: 09 December, 1999
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