Tower site construction involves many steps: building an access road; bringing in electric and phone lines; erecting a fence and installing other security measures; providing and installing the equipment shelter; erecting the tower and installing transmissions lines and antennas; and testing alignment of all lines and antennas. Some tower manufacturers will provide a turnkey program that packages all of these services, or you may contract with different suppliers for the various services.
Photo 7. Ice shields (black arrows) are used to protect parabolic antennas, such as this one atop a heavily loaded microwave tower. The polymer-coated fiberglass radomes (purple arrow) also shed ice and snow to maintain the integrity of the antenna feed.
Putting up a tower is not difficult when you know what information you need and accumulate it up front. Start by deciding what you want to accomplish with the tower both at the initial purchase and in the future. Select a tower manufacturer that stands behind its design, materials and service. Give that company all the information you can. Select a reputable tower installer to protect the investment you make in the equipment.
Finally, inspect and maintain your tower regularly.
GLOSSARY OF TOWER TERMS
The accompanying glossary identifies the terms most frequently used in purchasing a tower. Become familiar with them, and know which ones in particular affect the decision-making process for the tower you want to erect.
Antenna pipe mount A pipe used to mount an antenna to a tower. (See Photo 4.) This mount should be ordered with the tower when microwave antennas are part of the initial installation.
Cable safety climb A safety belt and cable worn by workers when they climb the tower. A locking device, which travels along the safety cable, is attached to the safety belt to prevent the climber from falling.
Cellular antenna platform A square and/or triangular platform that provides a safe working environment for cellular antenna installation and adjustment. (See Photo 5.) It also provides mounting support for antennas.
Cellular star mount A triplex frame that can support as many as 12 whip antennas with the other cellular antennas that are separated by 20 or 30 feet. (See Photo 6.)
Climbing ladder A ladder mounted either on the outside of a tower or internally such that two tower faces form a safety cage.
EIA Electronic Industries Association.
FAA dual red light/strobe system A kit of components needed to comply with FAA and FCC regulations. It consists of a combination of red light beacons and sidelights that flash after dusk and white strobes that flash during daylight hours. The flashing strobe could be a nuisance to the surrounding populated areas at night, so less objectionable red beacons are used. No paint is required for the tower.
FAA strobe light system A flashing white beacon at the top. No paint is required for the tower.
Grounding system A series of copper wires and buried rods used to ground the tower, shelter, and transmission line. It is one of the most important deterrents to lightning damage. One lightning strike could bring the entire system down, resulting in a loss of revenue.
Ice shield A canopy installed directly above an antenna to protect it from damage caused by falling ice and other windblown debris. (See Photo 7.)
Light controller A solid-state electronic device equipped with a photoelectric cell that turns tower lights on and off. Alarms indicate beacon, sidelight or power failures.
Paint A paint that adheres to galvanized steel. Painting is typically done in the field, but factory applied paint is also available. The FAA requires that towers 200 feet and taller be painted and/or lighted. Towers shorter than 200 feet may need painting and/or lighting if close to an airport. Painting consists of seven equally spaced bands, three of aviation white and four of aviation orange.
Radomes A cover installed over the antenna to protect the antenna and feed from accumulation of ice, snow and dirt and to help reduce wind loading. There are two basic types. Flexible planar radomes are stretched across the front of shielded antennas. They are made of either hypalon-coated nylon (lasts 5 to 15 years) or a polymer-coated fiberglass fabric (lasts 10 to 30 years). (See Photo 7.) The radome flexes slightly in the wind and thus sheds ice and snow and protects the antenna feed. The second type is a molded or formed radome, usually made of fiberglass or plastic. These radomes are parabolic (dish like) or cone-shaped and are attached to the rim of the reflector. They also provide protection to the feed even in severe environmental conditions.
Side arms Extensions from a tower that increase the clear distance between the antenna and the tower to minimize the interference created by the tower structure (See Photo 5.)
TIA Telecommunications Industries Association
Torque stabilizers An assembly of extended arms used on a guyed tower to help prevent twist. (See Photo 6.) They are generally attached above or below a microwave antenna.
Tower analysis A computer-generated report used to design new towers, to determine the modifications necessary to an existing tower before the addition of antennas, transmission lines, or accessories, or to change the height. Without a tower analysis, nothing should be added to a tower structure that was not specified in the original design.
Waveguide bridge A cover installed between the tower and shelter to protect the transmission lines from falling ice or any other debris.
Waveguide bridge/support system A system that supports the transmission line between the tower and the shelter entry ports (openings in the building where the cable enters).
Waveguide ladder A support system designed to attach the transmission line to the tower. In a guyed tower, this support system is usually built-in. It consists of diagonal braces (with pre-punched holes to accommodate hangers), which replace support diagonals at certain intervals. Waveguide ladders are also available for self-supporting towers. These supports bolt directly to the tower bracing for mounting transmission line without angle adapters or special brackets.
Copyright 2001 Florida Towers