AO51 satellite
 

the AO51 satellite common know as "Bird", is a FM repeater,one is Downlink
and uplink known as "pairs" Ham repeaters are found mainly in the VHF two
meter (144 - 148 MHz) and the UHF 70 centimeter (420 - 450 MHz) bands


http://en.wikipedia.org/wiki/Amateur_radio_repeater

but I still do not solve what made up a repeater in a schematics, I am not
intend to build a repeater out of the question.