EMR Uni-Directional Amplifiers (UDAs) provide a one way link (either uplink or downlink) inclusive of filtering and amplification of paging or base transmit signals into buildings, tunnels or areas that are shaded from adequate RF signal coverage, of portable transmit signals out. In addition to the UDA, other devices needed for a distribution system include transmission line, power splitters, hybrid & directional couplers, donor antenna, and Distributed Antenna System (DAS) antennas. Suitable for coaxial or radiating cable DAS. The choice of distribution method depends on the nature of the structure in which signal enhancement is required.