Evan J. Dutton

Abstract: The distribution of raindrop sizes in a given volume of air remains an unknown aspect of critical importance to the prediction of rain attenuation at millimeter–wave frequencies. Thus, in this report, the search continues for a methodology of predicting drop–size distribution with more apparent success than with earlier procedures developed by this author. The latest method involves prediction of the coefficients of a quadratic fit to the drop–size distribution. Climatology of rain attenuation also is pursued in this report, with more data from the Institute for Telecommunication. Sciences (ITS) millimeter–wave experiment undergoing analysis and, statistical examination to try to determine bounds on the specific attenuation that could be expected in a maritime climate (Gasquet, CA) and a dry continental, temperate climate (Boulder, CO). The data analyzed were all taken in 1985 at the three frequencies of 28.8, 57.6, and 96.1 GHz. Observed data were lumped into 1–min average specific rain attenuations for analysis. purposes in this report.

Keywords: millimeter waves; rain attenuation; attenuation distribution; attenuation climatology; raindrop size distribution

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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