by a remote control circuit from the ground, eliminating the need for a technician to climb the antenna tower. Use To increase or widen the coverage area, and thus the number of served clients, several sector antennas are installed on the same supporting structure, e.g. tower or mast. Such a construction is often called a sectorized antenna, though sometimes for brevity "sector antenna" is used as well. It has several angularly-separated sector antennas as shown on the figures at right. Once the antenna unit is attached to a supporting structure, it has to be positioned. Positioning means not only setting a correct direction or azimuth, but setting a correct downtilt as well. By restricting emitted energy to a sub-circular arc and narrow vertical coverage the design makes efficient use of relatively low power transmitter equipment. Though absolute range is limited, this configuration allows for good data rates (digital information transfer measured in bits/second, sometimes given as total minus error-correction overhead), and good signal consistency within the coverage area. Prior to positioning, grounding and lightning protection are required. As seen in the pictures, all supporting constructions have lightning rods. A well-chosen downtilt setting strategy can lower the overall interference in the network. A too-aggressive downtilting strategy will however lead to an overall loss of coverage due to cells not overlapping. Downtilting can be used to solve specific problems, for example local interference problems or cells that are too large. Electrical tilting slightly reduces beam width. In a picture on the right, there are two sector antennas with different mechanical downtilts. Note that a more vertical antenna is less visible than a mechanically tilted one - the use of purely electrical tilt with no mechanical tilt is therefore an attractive choice for aesthetic reasons which are very important for operators seeking acceptance of integrated antennas in visible locations. See also Antenna Radio frequency panel antenna, a similar type used in broadcast engineering External links Deploying License-Free Wireless Wide-Area Networks by Cisco Press Antenna Tilt Control in CDMA Networks P-CPICH Power and Antenna Tilt Optimization in UMTS networks Radio frequency antenna types Antennas (radio)