A. RF Repeaters
Repeaters are used to increase the range of a transmitted signal by re-transmission. For a conducted signal, an amplifier is used. Optical systems don’t amplify but all these devices give the appearance of doing so. A Repeater is needed to secure sufficient isolation between donor and service antenna. When the isolation is lower than actual gain + reserve (typically 5-15 dB) then the Repeater is in loop oscillation. Also cheap models are equipped with automatic gain reduction in case of poor or weak isolation. In case of poor isolation the device works but with low gain, and coverage is poor.
B. RF Antennas
The antenna is a vital part of any Repeater installation. Because the function of a Repeater is to extend the range of communications between mobile and portable stations, the Repeater antenna should be installed in the best possible location to provide the desired coverage.
External directional antenna: Generally the larger the external antenna the better the signal although even a small, correctly oriented external antenna should provide better signal than the internal antenna on any cell phone. These can either be fitted by professionals or will include a signal strength monitor for easy alignment.
Internal rebroadcast antenna: The better systems will generally include an internal monopole antenna (although the type of antenna is far from standardized) for rebroadcasting the signal internally – the advantage of using a monopole antenna is that the signal will be equally distributed in all directions
(subject, of course, to attenuation from obstacles). Because all radio antennas are intrinsically polarized, cell phones perform best when their antennas are oriented parallel to the booster’s antenna – although within reasonable proximity the booster’s signal will be strong enough that the orientation of the cell phone’s antenna will not make a significant difference in usability.
A. RF Repeaters