Kenneth C. Allen

Abstract: A simple model of the attenuation of millimeter waves by precipitating liquid water clouds is presented. As frequency increases from the microwave band into the millimeter wave band, the model indicates a significant increase in the relative importance of the attenuation due to the suspended liquid water of cumulus clouds in comparison with that due to the rain produced by the clouds. For the upper portion of the millimeter, wave band, the cumulative distribution of attenuation due to rain is overshadowed by the attenuation due to clouds. The need for an adequate cloud model for the accurate prediction of earth–space millimeter wave link performance is indicated. A short review of measurements of attenuation by clouds is presented for comparison with model predictions.

Keywords: millimeter waves; attenuation; attenuation distribution; cloud attenuation; clouds; millimeter-wave propagation

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