A dual band telescope for microwave instrument on Rosetta Orbiter (MIRO)

In this paper the requirements, specifications, design procedures, and analytical results for a dual frequency space-based telescope are discussed. The telescope is used as part of the microwave instrument on board the Rosetta Orbiter spacecraft, which will be launched early in the next century to rendezvous with and probe the Comet Wirtanen for water content and other material properties. The Offset-fed Cassegrain telescope reaches two receivers at millimeter (190 GHz) and sub-millimeter (560 GHz) via a beam waveguide arrangement. Gaussian beam and Physical Optics methods have been used in the successful design and analysis of the telescope. The telescope provides far field patterns with good efficiency better than 60%, and very low sidelobes better than 30 dB. RF properties of the telescope at varying temperatures, mechanical tolerances, and other operational situations are discussed