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Cumulative slant path rain attenuation statistics at 28.56 GHz are given for the year period April 1, 1977 through March 31, 1978 for Wallops Island, VA. These results were arrived at using the direct measurements of a beacon signal emanating from the Comstar geosynchronous satellite. Yearly, monthly, and time-of-day fade statistics are presented and characterized. In addition, a 19.04-GHz yearly fade distribution, corresponding to a second Comstar beacon frequency, is predicted using the concept of effective path length, disdrometer, and rain-rate results. Specifically, it is shown that the yearly attenuation and rain-rate distributions follow with good approximation lognormal variations for most fade and rain-rate levels, respectively. Attenuations were exceeded for the longest and shortest periods of times for all fades in August and February, respectively. These months thus represented the "worst" and "best" months at all attenuation levels. The eight-hour time period showing the maximum and minimum number of minutes over the year for which fades exceeded 12 dB were approximately between 1600-2400, and 0400-1200 h (local time), respectively. In employing the predictive method for obtaining the 19.04-GHz fade distribution, it is demonstrated theoretically that the ratio of attenuations at two frequencies is minimally dependent on raindrop-size distribution, providing these frequencies are not widely separated (such as 28 and 19 GHz).
Date of Publication: Nov 1979