Title: Radiometer Testbed Development for SWOT
Primary Author: Kangaslahti, Pekka
Organization: Jet Propulsion Laboratory
Co-Author(s): Pekka Kangaslahti, Shannon Brown, Todd Gaier, Dennis Harding, Douglas Dawson  - Jet Propulsion Laboratory

Abstract: Conventional altimeters include nadir looking co-located 18-37 GHz microwave radiometer to measure wet tropospheric path delay. These have reduced accuracy in coastal zone (within ~50 km from land) and do not provide wet path delay over land. The addition of high frequency channels to Jason-class radiometer will improve retrievals in coastal regions and enable retrievals over land. High-frequency window channels, 90, 130 and 166 GHz are optimum for improving performance in coastal region and channels on 183 GHz water vapor line are ideal for over-land retrievals.

We have developed MMIC LNAs that had more than 50% lower noise temperature (NT=300K) than previous state-of-art The MMIC LNAs enabled us to develop internally calibrated direct detect radiometer testbeds at the required observation frequencies. Our current 166 GHz radiometer system has a noise temperature of 455 K, bandwidth of 10% and operates with 60 mW of DC power.

The waveguide MMIC LNAs and radiometer testbeds were developed in ESTO IIP-07 task "Ka-band SAR Interferometry Studies for the SWOT Mission". The MMICs for this task were available from "Miniature MMIC Low Mass/Power Radiometer Modules for the 180 GHz GeoSTAR Array (MIMRAM)" technology development task within the ESTO Advanced Component Technology (ACT-05) program. The LNAs were also integrated in the airborne High Altitude MMIC Sounding Radiometer (HAMSR) that was developed under the IIP-98 and currently is funded to be installed onto the Global Hawk UAV for participation in NASA's Genesis and Rapid Intensification Processes (GRIP) hurricane field experiment in the summer of 2010.