Estimation of the cumulative attenuation distribution due to rain on a path exceeding 1lc2km, given the cumulative distribution due to rain on a path of 1km

Methods of forecasting the cumulative attenuation distribution at 94 GHz on various path lengths, using the value obtained for a 1 km path, are discussed. Where the probability of exceeding a specific attenuation is high, a path formed by a series of n paths, each of 1 km, is likely to suffer too. Where probability is low, the probability of a high attenuation value on a 1 km path, e.g., 15 dB, is assumed to be independent of the probability of the same attenuation on the following 1 km path in the series. The probability of exceeding a high attenuation value over the total path is determined by adding the values for that specific attenuation of all n 1 km paths. Differences for values around 15 dB are shown. Knowledge of the structure of rain showers should improve accuracy and investigation of a 5 km path is recommended.