The phase locked loop as a detector of the resonance absorption in gases [ESR spectrometers]

Attempts to construct the spectrometer with autodyne reception on the basis of commercial BWOs. The main differences of the proposed structure of the spectrometer from the usual absorption device are: the strong coupling between radiation source (BWO) and absorbing cell is provided; the detector at the output side of the absorbing cell is replaced by a mirror (adjustable short); the information about the gas absorption (real and imaginary parts of the susceptibility of the investigated gas) is obtained from the output of the phase locked loop (PLL) of the backward wave oscillator (BWO)