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Proceedings Paper

A new airborne Ka-band double-antenna microwave radiometer for cloud liquid water content measurement
Author(s): Jian Sun; Kai Zhao; Tao Jiang; Lingjia Gu
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Paper Abstract

A new type upward-looking airborne double-antenna microwave radiometer (ADAMR) system intended for detecting atmospheric cloud liquid water content (LWC) is developed in this paper. The frequency of this radiometer is 31.65 GHz. For the antenna elevation angle, one is 30°and the other is 90°. In order to detect the signals with low effective noise temperature (<10K) from the LWC, the noise coupling technique is used. Through injecting constant equal noise signal into the two antenna ports respectively, the technique can elevate the small input noise signal power to the detectable range of the square-law detector and thus realize the weak signal detection. Moreover, in order to eliminate the impacts of the system gain fluctuations and obtain a higher sensitivity, an auto-gain compensation method based on the analog-to-digital converter, microcontroller and host computer software techniques is also proposed. Compared with the traditional radiometers, the radiometer topology is greatly simplified and the gain fluctuations can be readily realtime compensated using the compensation method. The laboratory test results show that radiometric sensitivity is better than 0.2 K for 300ms integration time and the instrument is conforming to specifications. Finally, the flight observation experiment results are presented to prove that the designed instrument is able to detect small changes of noise signal in a wide effective range of noise temperature (10-350K) and is a powerful tool for LWC measurement.

Paper Details

Date Published: 23 September 2013
PDF: 8 pages
Proc. SPIE 8866, Earth Observing Systems XVIII, 886617 (23 September 2013); doi: 10.1117/12.2023023
Show Author Affiliations
Jian Sun, Jilin Univ. (China)
Northeast Institute of Geography and Agricultural Ecology (China)
Kai Zhao, Northeast Institute of Geography and Agricultural Ecology (China)
Tao Jiang, Northeast Institute of Geography and Agricultural Ecology (China)
Lingjia Gu, Jilin Univ. (China)

Published in SPIE Proceedings Vol. 8866:
Earth Observing Systems XVIII
James J. Butler; Xiaoxiong (Jack) Xiong; Xingfa Gu, Editor(s)

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