MicroNimbus: A Single-Chip 60 GHz SiGe Radiometer for Spaceborne Remote Sensing
Georgia Tech Research Institute Atlanta United States
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MicroNimbus is a 3U CubeSat under development at Georgia Tech that uses a 60 GHz radiometer to measure the temperature profile of the Earths atmosphere. Due to the characteristics of oxygen absorption around 60 GHz, by choosing different center frequencies and bandwidths, the radiometer can measure the temperature of the atmosphere at different altitudes, giving the temperature profile. This is of interest to weather forecasters and workers in LIDAR and laser communications, among others. The radiometer front-end is implemented using a single SiGe MMIC that includes a front-end calibration switch, an LNA, an image-reject mixer with an integrated LO frequency quadrupler, an IF amplifier, and a synthesizer. The fabricated MMIC achieves 65 dB of conversion gain with a noise figure of 6.5 dB 4.3 dB without the switch and an image rejection ratio of 31 dB. The required LO power is only -18 dBm and the total DC power is 180 mW. The low SWaP-C of this instrument would allow a constellation of such spacecraft to be deployed, yielding a continuous near-real-time 3-D map of the temperature profile of the Earths atmosphere. All key components of the SiGe radiometer have been fabricated and tested, and the CubeSat bus design is currently at a CDR level.
- Test Facilities, Equipment and Methods