The Soil Moisture Active-Passive (SMAP) L-band microwave radiometer is a conical scanning instrument designed to measure soil moisture with 4% volumetric accuracy at 40-km spatial resolution. SMAP is NASA's first Earth Systematic Mission developed in response to its first Earth science decadal survey. Here, the design is reviewed and the results of its first year on orbit are presented. Unique features of the radiometer include a large 6-m rotating reflector, fully polarimetric radiometer receiver with internal calibration, and radio-frequency interference detection and filtering hardware. The radiometer electronics are thermally controlled to achieve good radiometric stability. Analyses of on-orbit results indicate that the electrical and thermal characteristics of the electronics and internal calibration sources are very stable and promote excellent gain stability. Radiometer NEDT < 1 K for 17-ms samples. The gain spectrum exhibits low noise at frequencies >1 MHz and 1/f noise rising at longer time scales fully captured by the Piepmeier et al.
Abstract-Students at Brigham Young University have developed a new, low-cost Synthetic Aperture Radar (SAR) system, the BYU µSAR. The simple design, based on a linear frequency modulated continuous wave signal (LFM-CW), reduces the size and power compared to a conventional pulsed SAR system. This enables the BYU µSAR to fly on a small UAV, further reducing the cost of operation and extending the use of SAR into new areas. Design parameters and specifications for the BYU µSAR are presented in this paper, together with results from experimental data collection and test flights.
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