Precision resonator microwave spectroscopy in millimeter and submillimeterrange

By the use of Fabry-Perot resonator with quality factor similar or equal to : 600 000 and fast precision (down to one Hertz) frequency control of coher ent millimeterwave radiation source the 20 I-It accuracy in measurements of the width of resonance curve is obtained. This accuracy corresponds to the detection of 1.8 x 10(-3) dB/km absorption in the sample filling the reson ator and exceeds the before known sensitivity more than by an order of magn itude. The example of precise measurement of 60 GHz oxygen absorption band in the real atmosphere is presented. The new possibilities of application o f precision resonator microwave spectroscopy to the atmospheric problems as well as to the ultra-low absorptions measurements in dielectrics and metal surfaces up to Terahertz frequencies are discussed.