A Sensitive Cavity-Based Gas-Spectrometer for Broadband Operation at 26 - 40 GHZ

A highly sensitive microwave spectrometer for the analysis of gases has been developed, using a long H01-resonator. The system is tunable in the whole Ka-band, i.e. from 26 to 40 GHz. It employs a Stark modulation technique and has been optimized with respect to converted FM-noise and detector noise for maximum sensitivity. The spectra of several test gases have been measured with limiting sensitivities for e.g. SO2 of 3 ppm and C2H4F2 of 1.8 ppm at a 1 Hz filter bandwidth.