Signal field coverage improvements by means of antenna passive repeaters is explored by introducing a signal phase shifter to the traditional antenna passive repeater scheme, aimed at optimizing indoor signal distribution. The possible passive repeater schemes include an elevated outdoor high- or medium-gain omnidirectional antenna, and two antennas set on a building wall connected by coaxial cable. The electric field at each indoor point is found to be a vector sum of the field and the field radiated by the inside antenna. It is also found that for the brick wall, the passive repeater is effectively tuned by the phase shifter and its recovering efficiency can be increased by the use of more directive antennas. An external 12 dBi gain Yagi antenna positioned on a 7 m high terrace of the building and aimed at a line-of-sight is helpful in making antenna passive repeater installation.