Title of Presentation: MIMRAM — Miniature MMIC Low Mass/Power Radiometers for Geostationary Thinned Aperture Radiometer
Primary (Corresponding) Author: Pekka Kangaslahti
Organization of Primary Author: NASA Jet Propulsion Laboratory
Co-Authors: A. Tanner, B. Lambrigtsen, T. Gaier and D. Pukala of the Jet Propulsion Laboratory,
R. Lai and G. Mei of Northrop Grumman Space and Technology,
Abstract: Our technology development focuses on the receiver technology for the measurement of hurricanes and severe storms in the weather focus area and convection and clouds in the hydrologic-cycle focus area. A 183 GHz microwave sounder is particularly well suited to address those topics – much better than IR sounders, for example, which cannot penetrate substantial cloud and storm systems. We have designed 183 GHz MMIC low mass/power radiometers that enable continuous observation of the hemisphere from Geostationary orbit at 25 km resolution. Such a high resolution in combination with a short integration time is achieved by designing radiometer modules that have noise temperature (NT) of less than 500 K. Furthermore, these miniature modules can be integrated in arrays with 6 mm spacing that is required for Geostationary Synthetic Thinned Aperture Radiometer system (GeoSTAR).
The low noise radiometers perform low noise amplification and downconversion of the received signal to in-phase and quadrature baseband signals. This direct conversion approach minimizes radiometer complexity and enables narrowband measurements of upper and lower sideband signals. Recent technology advancement in Indium Phosphide MMIC technology enable us to design Low Noise Amplifiers (LNA) that have lower than
450 K NT at 165 to 183 GHz frequency range. These LNAs also provide 7 dB of gain per HEMT amplifier stage, thus significantly reducing the DC power consumption. We further reduced the local oscillator (LO) power consumption by implementing the latest diode technology in the second harmonic I-Q mixer. These mixers operate with less than +3 dBm of local oscillator power. The radiometer modules house two LNAs and a second harmonic I-Q mixer in a single leadframe package that weighs less than 30 g.