As America increases its reliance upon electronic communications, the sight of communication towers is becoming more common. The dramatic increase in mobile phone use and newer technologies, like wireless email and web access, has created a virtual explosion in tower construction. Communication towers are used for many types of electronic communication, including radio, cellular, EMS services and global positioning satellite technology.
These towers tend to be the most expensive to build. Used for television, microwave and power transmission, self-supported towers can have either three or four legs. Built on the ground or on buildings, these towers generally feature a lattice frame design. Self-supporting towers are the strongest and have the greatest resistance to ice and wind loads of any of the three communication tower designs. These towers can range from 30 to 490 feet high.
Monopole towers are of a single pole design and are generally used in cellular and personal communication service. They are free standing and are usually built cylindrically or with multiple sides. Monopole towers are often placed on the roofs of tall buildings. Each section of the monopole is welded or bolted together to a height ranging from 30 to 490 feet. The section with the largest diameter is at the bottom of the tower, with each successive section smaller as the tower rises.
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Guyed towers are lighter and more cost efficient than self-supporting towers where space is inexpensive. For this reason, guyed towers are more often used in rural settings. Three guy wires made of high-strength steel anchor the tower to the ground over an anchor radius equal to 2/3 of the tower's height. The central mast is made either of a triangular lattice section or tubular section to avoid icing. Guyed towers range in height from 25 to 625 feet.
Classification of Communication Towers
Communication towers classification is based on a number of considerations, including structural action, which denotes how the tower is erected; cross section, which indicates the shape of the towers (either square, hexagonal, polygonal or triangular); type of material sections, which refers to a tower's angular or tubular bracings; and type of surface it is placed on.
When a call is made on a cellular phone, the signal is transmitted by radio to the nearest antenna tower. Once the antenna site electronically determines that the originating phone is authorized to use its network, the message is then sent by radio -- for cell-to-cell calls -- or telephone line for calls to land lines. Cellular technology divides geographical regions into cells, each with its own radio receiver/antenna. These cells range in size from an individual building to 20 miles wide. When a cell phone customer gets too far away from one antenna, the network senses that the signal is getting weaker and relays the signal to the antenna of a closer cell.