Hans J. Liebe

Abstract: Atmospheric radio wave propagation in the 40 to 140 GHz band is influenced by microwave spectra of oxygen (O₂-MS) and water vapor. The report treats the complementary roles of controlled laboratory experiments and computer analysis for providing detailed molecular transfer characteristics. A pressure-scanning differential refractometer was operated at fixed frequencies between 58 and 61.5 GHz. The variability of O₂ and H₂0 spectra with frequency, pressure, temperature, and magnetic field strength was studied under conditions which occur in the atmosphere. Results obtained (a) for oxygen and air on the 9+ line, the 7+/5- and 3+/9- doublets, and the continuum spectrum and (b) for water vapor on nonresonant effects are reported. The experimental O₂-MS data are used in theoretical analyses of attenuation and d1spersion rates which are extended to other lines, to frequencies identified for remote sensing applications, and to temperature and pressure sensitivities between 40 and 140 GHz.

Keywords: millimeter-wave propagation; atmospheric propagation; attenuation profiles; dispersion profiles; EHF transfer characteristics; oxygen microwave spectrum; water vapor microwave spectrum

Disclaimer: Certain commercial equipment, components, and software may be identified in this report to specify adequately the technical aspects of the reported results. In no case does such identification imply recommendation or endorsement by the National Telecommunications and Information Administration, nor does it imply that the equipment or software identified is necessarily the best available for the particular application or uses.

For questions or information on this or any other NTIA scientific publication, contact the ITS Publications Office at ITSinfo@ntia.gov or 303-497-3572.

Back to Search Results