August 1983 | NTIA Technical Report TR-83-129
Climatological Coefficients for Rain Attenuation at Millimeter Wavelengths
Evan J. Dutton; C. E. Lewis; Francis K. Steele
Abstract: It is demonstrated that most of the classical raindrop-size distribution formulations give inconsistent results when used to calculate specific attenuations at millimeter-wave frequencies. For this reason, it was decided it might be desirable to subcategorizes dropsize distributions on the basis of large-scale worldwide climatological zones. This was done in the belief that different distributions will be needed in different environments to produce more accuracy in predicting millimeter-wave rain attenuation for a given location. Raindrop-size data taken over a span of about 40 years in these various climatic zones are discussed briefly in terms of common characteristics. Some empirical methods of drop-size distribution measurements are discussed, and 226 drop-size distributions are grouped broadly into four climatic zones and presented in terms of a well known model drop-size distribution formulation. Using these results, zonal coefficients for the standard specific attenuation-rain rate relationship are obtained by a couple of different least squares-regression procedures. While results are different from previous results, there is no distinct indication that they represent an improvement. A need for further work is then discussed.
Keywords: climate zones; millimeter-wave frequencies; raindrop-size distributions; specific attenuation
To request a reprint of this report, contact:
Lilli Segre, Publications Officer
Institute for Telecommunication Sciences
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.