The Advanced Communications Technology Satellite (ACTS) propagation experiment has collected four years of propagation data at 20.185 and 27.505 GHz. The objective of the experiment is to develop long-term statistics and modeling techniques for predicting atmospheric propagation effects in the Ka band. The experiment includes seven identical earth stations at different locations in North America. Each location is meant to characterize a unique rain region. This paper presents the data collected in White Sands, NM. The data from this site provide an excellent resource for validating rain attenuation models due to its unique arid climate with occasional high rain-rate storms. The seasonal and cumulative four-year attenuation statistics for the 20.2 and 27.5 GHz beacons are presented. The attenuation with respect to clear air (ACA) is compared to five different rain attenuation models and seven different frequency scaling models. The results illustrate how well each model predicts rain attenuation in a desert climate region.

This paper analyzes fade slope for the Alaska, Florida, and New Mexico Advanced Communications Technology Satellite (ACTS) propagation data at 20 and 27.5 GHz for the first two years of the experiment (December 1, 1993-November 30, 1995). The propagation experiment will continue to collect data for at least another 21 months. Fade slope is examined on a statistical basis for the three sites. The Florida and New Mexico receiver sites have very different weather characteristics but almost identical elevation angles, while the Alaska receiver terminal has an extremely low elevation angle. The cumulative statistics illustrate the relationship between fade slope, fade level, transmission frequency, and elevation angle for all three sites.

Important elements in the design of Ka-band communication systems are the duration of fade and nonfade events at a particular fade depth. The choice of modulation and forward error correcting codes will depend on both the fading time dynamics and annual fade occurrence statistics. This paper examines the fade duration measured at locations in three of the Advanced Communications Technology Satellite (ACTS) propagation experimental regions, namely, Florida (rain zone N of the radiocommunications sector of the International Telecommunications Union ~ITU-R\ model), New Mexico State University (ITU-R rain zone M), and Alaska (ITU-R rain zone C). Within each region, measures of the underlying uniformity are described and an interregional comparison examines the ability to scale the local results.