A repeater installed in a moving object is provided, in which a link antenna module has a plurality of link antennas steered to predetermined directions, for wirelessly communicating with a Base Transceiver Station (BTS), a link antenna path setting module selects at least one of the plurality of link antennas of the link antenna module and connects a path between the selected link antenna and a rear end, a service antenna module has at least one service antenna installed within the moving object, for wirelessly communicating with Mobile Stations (MSs) within the moving object, a relay signal processing module is connected to the link antenna module through the link antenna path setting module and processes transmission and reception relay signals between the link antenna module and the service antenna module, a movement information module measures current movement information about the moving object and provides the current movement information, a received signal measuring module measures a received signal of the link antenna module and providing current propagation environment information, and an antenna control module detects a current movement state and a current propagation environment based on the information received from the received signal measuring module and the movement information module, stores and/or updates the information in an internal propagation environment information storage, and controls the link antenna path setting module to select a link antenna that receives the best signal from a serving BTS at each location according to the stored information.