A transponder is a radio or radar system that is triggered by a received signal. Transponders are important components of communications satellites and consist of a receiver, a frequency converter, and transmitter package. They have a typical output of 5–10 watts, operate over a 36–72 MHz bandwidth in the L-, C-, Ku-, or Ka-band, except for mobile satellite communications. Communications satellites typically have 12–24 onboard transponders, although the Intelsat VI at the extreme end has 50.