High-precision millimeter-wave spectrometer

An essential improvement of automated high-precision millimeter-wave spectrometer is described. In order to investigate lineshapes a multimode frequency modulation of radiation source is realized. Matching of quasioptic absorbing cell with radiation source and detector was improved to reduce well-known problem of standing waves. PLL systems were essentially improved that allowed us to realize survey mode of spectrometer operation. For the frequency step about 50kHz the speed of survey spectra recording is about 10 GHz per hour (using the synthesizer-based mode). The whole frequency range of the spectrometer is 48-148 GHz.