Vector Signal Processing for 60-120 GHz Gas Absorption Measurement

Toshitatsu SUZUKI  Hidenori SASANUMA  Masashi SANO  Kenichi SHIODA  Yasuo WATANABE  

IEICE TRANSACTIONS on Electronics   Vol.E84-C    No.12    pp.1900-1904
Publication Date: 2001/12/01
Online ISSN: 
Print ISSN: 0916-8516
Type of Manuscript: Special Section PAPER (Special Issue on New Technologies in Signal Processing for Electromagnetic-wave Sensing and Imaging)
millimeter/submillimeter wave,  spectroscopy,  gas temperature and pressure,  in-situ gas sensor,  vector measurement,  

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This study is intended to realize an in-situ gas sensor based upon the principle of millimeter/submillimeter wave spectroscopy. In-situ gas sensor will be attractive because of gas selectivity, multiple parametric measurement such as gas temperature, pressure and density, and of the in-situ measurement capability. One of the major technical problem to be solved is to develop an instrument accurate enough to discern the spectrum change due to the variation of parameters such as temperature. In this paper a proposed gas absorption measurement system is investigated, which schematically consists of Fabry-Perot type gas cell for effective long path length, and vector signal processing to reject leak signal coupled between resonator input and output ports so as to achieve precise absorption measurement. Also included is an parametric study of oxygen absorption characteristics, which is served as the predicted value in the evaluation of the instrument. The experiment at 60 GHz and 120 GHz bands using oxygen demonstrates the effectiveness of the current system configuration.