Hans J. Liebe and George A. Hufford

Abstract:

Two millimeter-wave propagation models, called MPM and MZM, are discussed. The first one predicts, at frequencies up to 1000 GHz, loss and delay effects for a nonprecipitating atmosphere. Contributions from dry air and vapor are addressed, as well as suspended water droplets that simulate fog or cloud conditions. For clear air, a local spectral line base is employed (44 O₂ + 30H₂O lines) complemented by an empirical water-vapor continuum. Droplet effects are treated with the approximate Rayleigh scattering theory. Input variables are barometric pressure, temperature, relative humidity, and droplet concentration.

At heights between 30 and 100 km, the spectral lines of oxygen result in an anisotrophic medium due to the geomagnetic Zeeman effect. The computer program MZM was developed to analyze propagation of plane, polarized radio waves in the vicinity (±10 MHz) of O₂ line centers positioned in the 60-GHz band and at 119 GHz. Results are displayed that demonstrate many aspects of the ususual wave propagation through the mesophere.

This paper was delivered during the Electromagnetic Wave Propagation Panel (EPP) Specialists' Meeting held in Copenhagen, Denmark, 9th–13th October 1989. Conference proceedings No. 454 were hosted by the North Atlantic Treaty Organization (NATO) Advisory Group for Aerospace Research and Development (AGARD). The title of the symposium was "Atmospheric Propagation in the UV, Visible, IR and MM-wave Region and Related Systems Aspects. The proceedings were published March 1990.

Keywords: millimeter waves; millimeter wave; millimeter-wave frequencies; millimeter-wave propagation; water vapor; Zeeman effect; dry air; millimeter-wave propagation model; MPM; MZM

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