Heterodyne repeater

Heterodyne repeater: In radio reception and retransmission, a repeater that converts the original band of frequencies of the received signal to a different frequency band for retransmission after amplification.

Radio repeaters usually operate in the FM (frequency modulated) mode and are common in commercial two-way and Amateur (Ham) Radio communications. The repeater devices generally use the VHF and UHF frequency bands and operate using line-of-sight propogation from the tops of mountains, tall buildings and towers, giving small mobile and handheld radios radio coverage for hundreds of miles.

Note: Heterodyne repeaters are used, for example, in microwave systems, to avoid undesired feedback between the receiving and transmitting antennas. Synonym IF repeater.

Source: from Federal Standard 1037C and from MIL-STD-188