Actuators provide the mechanical drive to allow an antenna to scan the arc of satellites under remote control. In the early 1980s there were only a limited number of satellites in the geostationary orbit over North America so most antennas were either fixed on one target or hand-cranked between communication spacecraft. However, as more satellites began to relay television programming, antennas had to be moved from one satellite to another. Manually moving a three or four meter dish in, for example, cold and wet weather was not an attractive proposition. In addition, even when only one satellite is to be targeted, inclined orbit tracking systems must sometimes be used.ny systems feature either linear or horizon-to-horizon actuators. Linear actuators have a telescoping arm that moves within a fixed external tube. Horizon-to-horizon actuators are attached to the base of an antenna and are solidly constructed to generate the torque necessary to rotate a dish and to allow minimal movement in winds or under other loads such as heavy snows. When designing a system to receive satellites close to the horizon it is important to realize that linear actuators typically has a more limited range of motion than a horizon-to-horizon devices.