March 1985 | NTIA Technical Report TR-85-171

Millimeter-Wave Propagation in Moist Air: Model Versus Path Data

Hans J. Liebe; Kenneth C. Allen; Gregory R. Hand; Richard H. Espeland; Edmond J. Violette

Abstract: A practical atmospheric millimeter-wave propagation model (MPM) is updated and tested with experimental data from horizontal, line–of–sight links when there is no precipitation. The MPM computer program predicts attenuation and delay properties of moist air over ranges in frequency from 1 to 1000 GHz and in height from 0 to 30 km. Input variables are radio path distributions of pressure, temperature, relative humidity, and a suspended droplet concentration simulating haze and fog conditions. Terrestrial path data from millimeter–wave propagation experiments, including those from a 27 km link operated at 11.4, 28.8, and 96.1 GHz by the Institute for Telecommunication Sciences (ITS), have been analyzed. Calibrated mean signal levels permitted studies of water vapor losses. In addition, a spectral analysis was performed of clear-air scintillations caused by turbulence. In general, good agreement is obtained with the MPM for test frequencies up to 430 GHz.

Keywords: atmospheric attenuation and delay; millimeter wave properties of moist air; propagation program MPM; terrestrial radio path data

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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.

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