A communication satellite functions as a radio relay in space. The communication link may be between stations on earth, or between antennas from other satellites.
One way to increase the capacity of the system is to increase the bandwidth (bw). The bandwidth may be increased through frequency reuse, or in cases where the carrier-to-noise power ratio (CN) is fixed, it may be increased by reducing the coverage area (Acov). In turn, the coverage area may be reduced by using a multibeam antenna, where the power is divided among the beams.
Other parameters of the equation include the satellite transmitter power (Pt), earth station antenna effective area (Ar), equivalent system temperature (Ts) and incidental loss (Li).