Millimeter-wave spectrometers for remote sensing of ozone and other minor gases of the atmosphere

A new transportable 142 GHz ozone spectrometer (ozonometer) is created at P.N.Lebedev Physical Institute. Its room temperature heterodyne receiver operating in amplitude-switching mode is based on planar Schottky diode mixer. Both low-loss input Gaussian optics and solid-state Gunn-diode local oscillator are used in the receiver. Optical block of the receiver includes antenna, chopper wheel, room-temperature (hot) calibration load, reference load with brightness temperature varying within 100-300 K, SSB filter, path length modulator, diplexer, focusing off-axis elliptic and parabolic mirrors, corrugated horns to launch Gaussian beams, the mixer, the local oscillator, preamplifier of the first intermediate frequency (IF1) 3.5-4.0 GHz, and control interfaces.