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arXiv · 0712.0911

Implementation of an Optimised Cassegrain System for Radio Telescopes

C. M. Holler·R. E. Hills·M. E. Jones·K. Grainge·T. Kaneko
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Abstract

We present the antenna design for a radio interferometer, the Arcminute Microkelvin Imager, together with its beam pattern measurement. Our aim was to develop a low-cost system with high aperture efficiency and low ground-spill across the frequency range 12-18GHz. We use a modified cassegrain system consisting of a commercially-available paraboloidal primary mirror with a diameter of 3.7m, and a shaped secondary mirror. The secondary mirror is oversized with respect to a ray-optics design and has a surface that is bent towards the primary near its outer edge using a square term for the shaping. The antennas are simple to manufacture and therefore their cost is low. The design increased the antenna gain by approximately 10 per cent compared to a normal Cassegrain system while still maintaining low contamination from ground-spill and using a simple design for the horn.

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C. M. Holler, R. E. Hills, M. E. Jones, K. Grainge, T. Kaneko. 2007-12-06. Implementation of an Optimised Cassegrain System for Radio Telescopes. https://doi.org/10.1111/j.1365-2966.2007.12792.x

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