The torus-shaped radiation pattern 202 of an omnidirectional antenna 200, is shown in FIG. 2a (side view) and FIG. 2b (top view). Radial distance from the centre indicates the power radiated (which reaches a maximum in the horizontal, or azimuth plane and drops to zero directly above and below the antenna. Antenna 200 radiates power equally in all directions in the azimuth plane.

FIG. 3 shows an omnidirectional antenna 300, a bi-directional amplifier 302 and three rebroadcast panel antennas 304. The signals collected by omnidirectional antenna 302 are directed to the bi-directional amplifier for amplification and distribution to the rebroadcast antennas. Since the donor external is omnidirectional antenna, signals emanating from all azimuth directions (including background noise) will be collected passed to the bi-directional amplifier 302 and amplified equally. Existing bi-directional amplifiers are high-power and offer maximum gains of around 100 dB. However, signals from particular cellular towers cannot be filtered from the background noise, and as such a bi-directional amplifier of high gain will still fail to compensate for the low gain of the omnidirectional antenna.