A Ka-Band Active Electronically Scanned Array (AESA) Line Feed for Future Spaceborne Radar

Radar has been identified as a primary sensor for the high priority Cloud, Convective and Precipitation (CC&P) mission in the recent NASA Earth Science Decadal Survey 2017 report. Through support from the NASA Earth Science Technology Office (ESTO) Instrument Incubator Program (IIP), NASA Goddard Space Flight Center (GSFC) and Northrop Grumman Mission Systems (NGMS) developed a next generation multi-frequency spaceborne radar concept using a shared primary reflector and active phased array line feeds. At Ka-Band (35 GHz) cross-track scanning is achieved by a line array comprised of several hundred Transmit-Receive (TR) modules that feed the primary reflector and provide an ultra-low sidelobe antenna pattern. Ka-Band TR module based on solid state MMIC technology has been developed, mainly at NGMS under the collaboration with GSFC. This presentation provides an overview of the design and reports measured data for key components and module level parameters. Solutions to the key design challenges that achieve the unique mission goals, such as generating Ka-Band transmit signal using highly efficient solid state power amplifiers, a very low noise figure, a low power receiver with ultra-low antenna sidelobes needed to mitigate earth surface clutter, and overall strategies to achieve very low power dissipation will be discussed. Key MMIC component technology advancements using Gallium Nitride, Gallium Arsenide and Silicon will also be presented. Packaging of the Ka-Band MMIC components in an integrated module that is easily assembled into line array architecture will also be discussed.