A guy wire is a stabilizing brace used to secure or steady a sign or structure. It can be made of rope, wire, or cable. One end of the wire is attached to the structure or sign and the other end is anchored at a distance to a stable ground object through tension. These wires are commonly used to brace tents, ship and radio masts, utility poles, wind turbines, awnings, or canopies.
To permit the tension of several guy wires to offset the tension of others and provide optimum support, they are frequently equally spaced around the structure. This configuration can be trios, pairs of pairs, or other sets appropriate to the structure being secured. An example of a once-common trio configuration would be a residential roof television antenna secured by three evenly spaced wires.
Electrical utility poles are good examples of shorter, stronger structures that only need a single guy wire to stabilize against the pull of the electrical wires attached to it. Some wires are on structures so tall that aircraft safety markers must be attached to ensure their visibility. Another common use is on a sailboat, where a rope is used to control the end of a spar or spinnaker pole. Depending on the boat, one or more guy ropes may be needed for stability.
Mast antennas are the most common structures that regularly use guy wires for stability. The material used for a guy wire is important when a mast antenna is involved, as the metal or other highly conductive substance and length of the wire can greatly influence radiation signal patterns. They can also obstruct signals on the ground if they are in close proximity to the site.
To prevent interference, porcelain insulators were used in the past as dividers on the guy wire if it was to be used in conjunction with a mast antenna. The insulators prevented the development of large static electricity pockets that could cause hazardous discharges. Attentive maintenance to these insulators was necessary to prevent the mast from collapsing.
In recent years, many mast antennas are manufactured with insulators already installed and grounded with coils on the ground. This prevents the guy wire from interfering with the radiation patterns. It also makes maintenance of the structure easier and safer.
An alternative to the steel guy wire commonly used on mast antennas is a wire made of non-conductive polymers or plastics. This option alleviates interference caused by steel wires. It is not a popular choice in most cases, however, as the polymers do not withstand weather very well and must be regularly replaced.