The influence of heavy rainfall on attenuation at 18.5 and 30.9 GHz

Percent-of-time distributions of rain-induced fades obtained on a 6.4-km path in New Jersey operating at a frequency of 18.5 GHz are discussed for the period of 1968-1969; data obtained at 30.9 GHz on a 1.9-km path for the same period are also discussed. The attenuation distributions are compared with attenuations calculated from the distributions of average rain rates on the paths. With these data, it is found that distributions of attenuation can be predicted from the path-average rain-rate distributions for a given sample period. Detailed rain-rate and attenuation measurements at 18.5 GHz on the 6.4-km path are presented for the most intense storm observed in a three year recording period. Point rain rates in excess of 250 mm/h and path-average rates exceeding 180 mm/h were observed; the attenuation exceeded the 50-dB dynamic measuring range of the equipment for more than seven minutes.