dietcha
2012-07-09, 10:05 PM
Downtilting base station antennas is frequently done in mobile communications systems to prevent interference to other cell sites and to attain better coverage below a high-elevation antenna site. The downtilt can be a solution for cochannel interference in many situations. As use increases, downtilting base station antennas could become even more common. For omnidirectional antennas, it is usually best to use electrical downtilt. For directional antennas, mechanical downtilt is often used. Mechanical tilt is used when flexibility in changing the downtilt is desired. The electrical tilt is usually fixed at a set angle at the time of manufacture. This is changing now that antennas with adjustable electrical tilt are being introduced. A normal base station antenna may lose approximately 1 dB of gain from tilt