Kenneth C. Allen, Hans J. Liebe, and Charles M. Rush

Abstract: Attenuation by the atmosphere can severely limit the use of the radio spectrum above 10 GHz for telecommunication purposes. In this report brief discussions of three mechanisms that attenuate millimeter waves in the atmosphere are presented: rain attenuation, clear air absorption, and atmospheric multipath. Propagation models developed by personnel at the Institute for Telecommunication Sciences and by others were combined with meteorological statistics to obtain estimates of average year attenuation distributions for 18 cities in the United States. The estimates are presented in such a way to elucidate the restrictions on system parameters required for reliable operation, i.e. frequency, path length for terrestrial paths, and path elevation angle for earth–satellite paths. The variation imposed by the diverse climates within the United States is demonstrated. Generally, in regions that have humid climates, millimeter wave systems perform less favorably than in areas where arid or semi–arid conditions prevail.

Keywords: radio propagation; millimeter wave attenuation; millimeter wave model; millimeter wave systems

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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