I. Introduction
Although rain fading on Earth-space links is particularly troublesome in the Ka-band, moving to higher frequencies offers many potential advantages, including a less-congested spectrum, the possibility of supporting higher system bandwidths (and higher data rates), reduced interference potential, and smaller equipment size (particularly smaller antennas) compared with lower frequencies [1]. At present, most Ka-band Earth-space links are used to increase the capacity of conventional communications satellites located in geostationary Earth orbit (GEO). In recent years, however, system designers have begun to show serious interest in using Ka-band links to provide high-speed data communications with satellites in low Earth orbit (LEO) during the relatively short time that a LEO satellite passes within the range of an Earth station.