ABSTRACT
This chapter is an overview of the technology of satellite communication systems used for the transmission and distribution of radio and television programs. Communication of electrical signals is done by direct physical connection, such as wires or fiber-optic cables, or by radiation of radio frequency or optical waves. In radiated communication, the use of satellites for relaying signals has significant advantages in certain applications. In order to send signals between points on the earth’s surface, the signal is radiated up to a satellite in orbit and then relayed back down to earth where it is received at a different place. Earth station antennas have very narrow beams, both to increase their gain and to avoid interference with adjacent satellites. By contrast, the antennas on communication satellites usually have rather broad beams so that they can provide service to and from a large area—typically an entire region, country, or even an entire hemisphere.
