Satellite site diversity: Results of a radiometer experiment at 13 and 18 GHz

Joint attenuation statistics for a model site-diversity satellite system which would operate at 18 and 30 GHz were gathered in a radiometer experiment conducted at sites near Atlanta, GA, and Denver, CO. The receiver is of the classic Dicke radiometer type, monitoring sky-noise power at 13.6 and 17.8 GHz. Scaling provides the means to derive 30 GHz performance. The experiment, which commenced in May 1973, provides an expedient means of acquiring essential rain attenuation statistics without the use of active signal sources, such as a satellite beacon. This article describes the experiment and presents the results, including representative data samples from the 1½A year measurement period. Based on these measurements, a model satellite system operating during, the measuring period in Atlanta, at 18 and 30 GHz with 8 and 18 dB fade margins, respectively, would require 14-mi site diversity to insure no more than 0.005 percent propagation outage. During the same time period, site diversity was found unnecessary to satisfy this objective with operation in Denver.