A method for calculating rain attenuation distributions on microwave paths

An engineering method is proposed for calculating rain attenuation distributions for frequencies greater than 10 GHz and for paths of arbitrary length. The technique is based upon the observed approximate lognormality of rain attenuation and rain rate statistics within the range of interest; it reflects local meteorology through incorporation of the observed point rain rate distribution. Some important parameters in the resulting formulas are determined empirically from experimental data. Sample calculated results agree well with available experimental data from Georgia, New Jersey, and Massachusetts. This new technique may prove useful for engineering radio paths at frequencies above 10 GHz. Sample calculations of expected outage probability are given for 11- and 18-GHz radio links at Atlanta, Georgia, as a function of repeater spacing and transmission polarization.