Suggested quasi-Cassegrain system for multi-beam observation of FAST

FAST, the largest single-dish radio telescope in the world, has a 500-meter diametermain reflector and a 300-meter diameter illuminated area. It has amain reflector that can vary its shape, which continuously changes the shape of the illuminated area in reflector into a paraboloid. In this article,...

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Bibliographic Details
Published inResearch in astronomy and astrophysics Vol. 20; no. 1; pp. 1 - 5
Main Authors Su, Ding-Qiang, Bai, Hua, Cui, Xiang-Qun
Format Journal Article
LanguageEnglish
Published Beijing National Astronomical Observatories, CAS and IOP Publishing Ltd 01.01.2020
IOP Publishing
Subjects
Image quality
instrumentation: miscellaneous
methods: miscellaneous
Parabolic bodies
Phased arrays
Radio telescopes
surveys
techniques: miscellaneous
telescope
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Summary:FAST, the largest single-dish radio telescope in the world, has a 500-meter diametermain reflector and a 300-meter diameter illuminated area. It has amain reflector that can vary its shape, which continuously changes the shape of the illuminated area in reflector into a paraboloid. In this article, we propose a quasi- Cassegrain system for FAST. The detailed design results are provided. Such a quasi-Cassegrain system only needs to add a 14.6-meter diameter secondary reflector, which is close to the size of the feed cabin. The distance from the secondary reflector to the focus is only 5.08m, and it has excellent image quality. In this quasi-Cassegrain system, the shape of the illuminated area in the main reflector continuously changes into an optimized hyperboloid. Using this quasi-Cassegrain system from frequency 0.5GHz to 8GHz, the multi-beam system can include 7 to 217 feeds. If this system is used in combination with Phased Array Feed (PAF) technology, more multi-beam feeds or a higher working frequency can be used.
ISSN:1674-4527
DOI:10.1088/1674-4527/20/1/1