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How to Build a Safe Stable Antenna Tower

Amateur radio operators erect towers to place their antennas above trees, houses and other obstructions that degrade the signal. Most are directional-beam antennas, which use motors to rotate the antenna for the best reception. Amateur antennas are constructed in one of four ways. Guyed towers are supported by guy wires extending radially and anchored to the ground. Free-standing towers rely entirely upon the ground base without additional support. Fold-over towers are hinged at the base or first segment so they can be tilted for antenna access with no climbing required. Crank-up antennas have telescoping sections that can be raised and lowered. While construction techniques vary according to the specific manufacturer, a number of universal considerations apply when erecting an amateur radio tower.

Instructions

- 1
  Consult with government zoning officials about local laws before purchasing a tower. Municipalities and counties may limit antenna tower height or prohibit amateur towers entirely.
- 2
  Make sure you have sufficient space to locate the tower. Verify clearance to nearby structures so your tower will not hit your neighbor's house or contact electrical lines if it falls. Make provisions to secure access to the base of your tower so children or vandals cannot climb it.
- 3
  Choose a tower rated for the average wind speed rating of your county. Wind speed ratings for all 3,076 counties in the U.S. are issued in the TIA-222 Tower Standards, which are available online from many sources. Some municipalities may require a tower rated to a higher wind speed than the TIA-222 recommendation.
- 4
  Use a proper mast. The top segment of the tower to which the antenna is actually mounted is usually made of metal pipe or tubing. Pipe is rated for containing and carrying liquids; it does not carry any strength rating relevant to tower stresses, such as wind loads. Carbon steel tubing has a listed strength rating and makes a better choice for the mast.
- 5
  Select non-corroding hardware intended for outdoor use. All hardware should be galvanized or stainless steel. Common hardware-store nuts and bolts are not suited for exposure to the elements on an elevated tower. Use only SAE-graded nuts and bolts on tower legs. Make sure all eyebolts are the closed-eye variety and guy wires are extra high strength galvanized steel.
- 6
  Tension guy wires properly. Guy wire tension should be kept at 10 percent of the wire's breaking point. Too little tension will cause "wind slamming," placing strain on the wires as the tower blows back and forth. Too much tension stresses the guy wires beyond their limit and reduces the safety factor. Most amateur towers use 3/16-inch guy wires with a breaking point of 4,000 pounds and a recommended tension of 400 pounds. A commercially available tensioner gauge is recommended for accurate tensioning of guy wires.
- 7
  Incorporate a proper grounding system. A lightning strike to an improperly grounded tower can cause enough structural damage to make the tower fall. Proper grounding also minimizes RF interference to nearby electronic devices.

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