A nonstationary microwave spectrometer

Abstract

A submillimeter spectrometer for measurements of low concentrations in gas mixtures is developed and created. The radiation source is a 260–380 GHz backward wave oscillator (BWO). The BWO frequency is stabilized by means of a reference microwave channel, incorporating a cell with a gas under test the spectral line of which is used as frequency discriminator. Fast frequency scanning in the vicinity of the spectral line is used to reduce the effects of acoustic noise and vibrations and to upgrade time resolution. The background’s signals due to interference in the measuring cell of the spectrometer are suppressed by using a original nonstationary modulation method. Theoretical analysis of that method has been carried out. A description of the design and analysis of possible applications for the spectrometer, as well as the results of some experimental studies supported by the spectrometer are provided.