For humidity and temperature sounding of Earth’s atmosphere, a single-antenna/LNA (low-noise amplifier) is needed in place of two separate antennas for the two frequency bands. This results in significant mass and power savings for GeoSTAR that is comprised of hundreds of antennas per frequency channel. Furthermore, spatial anti-aliasing would reduce the number of horns. An anti-aliasing horn antenna will enable focusing the instrument field of view to the “hurricane corridor” by reducing spatial aliasing, and thus reduce the number of required horns by up to 50 percent.

The single antenna/receiver assembly was designed and fabricated by a commercial vendor. The 118–183-GHz horn is based upon a profiled, smoothwall design, and the OMT (orthomode transducer) on a quad-ridge design. At the input end, the OMT presents four very closely spaced ridges [0.0007 in. (18 μm)]. The fabricated assembly contains a single horn antenna and low-noise broadband receiver front-end assembly for passive remote sensing of both temperature and humidity profiles in the Earth’s atmosphere at 118 and 183 GHz. The wideband feed with dual polarization capability is the first broadband low noise MMIC receiver with the 118 to 183 GHz bandwidth.

This technology will significantly reduce PATH/GeoSTAR mass and power while maintaining 90 percent of the measurement capabilities. This is required for a Mission-of-Opportunity on NOAA’s GOES-R satellite now being developed, which in turn will make it possible to implement a Decadal-Survey mission for a fraction of the cost and much sooner than would otherwise be possible.

This work was done by Daniel J. Hoppe, David M. Pukala, Bjorn H. Lambrigtsen, Mary M. Soria, Heather R. Owen, Alan B. Tanner, Peter J. Bruneau, Alan K. Johnson, Pekka P. Kangaslahti, and Todd C. Gaier of Caltech for NASA’s Jet Propulsion Laboratory. NPO-47351

This Brief includes a Technical Support Package (TSP).
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Single-Antenna Temperature- and Humidity-Sounding Microwave Receiver

(reference NPO-47351) is currently available for download from the TSP library.

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