Space diversity and fade duration statistics at C-band for two overwater, line-of-sight propagation paths in the mid-Atlantic coast

Abstract

The authors characterize space diversity and fade duration statistics at 4.7 GHz for two line-of-sight (LOS) overwater links in the mid-Atlantic coast of the United States. Single-terminal and joint probabilities are generated for both annual and monthly cases for fade and fade duration distributions over the year period from June 1, 1989 to May 31, 1990. The fade and duration distributions during the months November-June were heavily biased by sustained deep fade events. These events were caused by persistent and severe subrefraction, which generally existed simultaneously over both sites. Although the height geometries are dissimilar (13.7 m and 45.5 m), these events mitigated the effectiveness of space diversity. During periods in February and March 1990, for example, fading continuously exceeded 20 dB (relative to the free-space power) at both sites for a duration in excess of 24 h. Space diversity does however appear effective during those months in which fading were predominantly caused by ducting (July-October) and when sustained deep fade events were generally not present. >