Title: An 8-40 GHz Wideband Instrument for Snow Measurements
Author: Timothy Durham
Organization: Harris Corporation

Abstract:
For this newly awarded IIP effort, Harris Corporation will team with engineers from NASA Goddard/Glenn and scientists from three Universities to build and test a wideband instrument (8-40 GHz) in support of the Tier III Snow and Cold Land Processes (SCLP) mission as defined by the Decadal Survey. Multiple instruments will be required to achieve the baseline SCLP mission goals using conventional technology. The capability to perform multiple NASA missions in a single instrument will be further developed on this effort by combining a wideband aperture with a software reconfigurable payload capable of performing multiple functions.

The broad bandwidth of this instrument allows flexibility in the number of frequencies used to measure Snow Water Equivalent (SWE), a primary goal of SCLP. Potential improvements in the estimation of SWE and its spatial/temporal variability have significant implications for hydrologic modeling and water resources management on a global scale. The wideband approach can also mitigate RFI by selecting non-interfering channels. Another advantage of a wideband antenna feed is the potential for co-boresighted beams at widely spaced frequency bands. This reduces measurement uncertainty due to a different area being imaged at different frequencies. An innovative manufacturing method for the wideband antenna will reduce the size and weight of the payload while adding additional functionality. The cost and power required for the instrument is expected to remain relatively unchanged.

The entry technology (8-40 GHz feed) is currently at TRL 3 for this application. The planned program is expected to bring the wideband feed/reconfigurable radar/radiometry payload, to an exit TRL of 6 for airborne applications. We will demonstrate the wideband feed and payload in both ground and airborne experiments during a 30 month period of performance. The first year demonstrates the compatibility of an existing wideband feed (2-18 GHz) with multiple existing radars to measure SWE of documented snow. In the second year, a wideband (8-40 GHz) passive array will be fabricated and integrated with a reconfigurable payload (SAR/radiometer). During the third year, flight tests on the NASA P3 and data reduction with new algorithms will investigate the science benefits of a wideband feed with a reconfigurable payload.