30 November 2017 Quasi-optical triplexing feed for spacecraft radiometer
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Proceedings Volume 2104, 18th International Conference on Infrared and Millimeter Waves; 21048M (2017) https://doi.org/10.1117/12.2298742
Event: 18th International Conference on Infrared and Millimeter Waves, 1993, Colchester, United Kingdom
Abstract
A sounding radiometer called AMSU-B has been developed for the UK Met Office. It is designed to measure altitude profilesof atmospheric water vapour over a ± 50° swath from low Earth orbit. Upwelling radiation is collected by a common aperturedual reflector with a rotating 90° offset main dish. A quasi-optical (QO) triplexing feed then successively separates the inputinto frequency bands at 89 GHz, 150 GHz, and 183.3 GHz by means of dichroic filters, and conveys it to the appropriate receiversvia chains of off-axis mirrors [1]. We present here predicted and measured performance, and describe the design method requiredto meet the following constraints for all three channels: beam efficiency __ 95%, half-power beamwidth 1.1° ± 10%, andtemperature measurement accuracy of 1.0 K. The bandwidths are 3 GHz for the two low frequency channels, and 16 GHz forthe 183 GHz channel.
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R. J. Martin, R. J. Martin, } "Quasi-optical triplexing feed for spacecraft radiometer", Proc. SPIE 2104, 18th International Conference on Infrared and Millimeter Waves, 21048M (30 November 2017); doi: 10.1117/12.2298742; https://doi.org/10.1117/12.2298742
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