To avoid the adverse influence of fading and to secure stable communication quality even at any places of the long and narrow dead zone of a radio wave by containing the transmission directivity of repeater antennas in a vertical plane containing the respective repeater antennas and arranging the respective transmission directivities in the same directions.

The plural repeaters 3 are installed in the long and narrow dead zone of the radio wave such as a tunnel and an underground passage. The repeaters 3 are connected with a transmitter/receiver 1 installed on the outside by an optical fiber 2. The repeaters 3 have the transmission directional antennas 4a and the reception directional antennas 4b (the repeater antennas 4 are the general term), and the center directions of the directivities of the antennas 4a and 4b are arranged in the same plane and the same directions. In a zone between the repeater antennas 4, the radio wave enters the directional area of one repeater antenna and it does not enter the directional area of the other repeater antenna. Thus, the adverse influence of fading can be avoided even at any places of the dead zone.