Back Vent (tirant) Catalan Bardun Danish Pardune German Guía (cable) Spanish گره (مهندسی) Persian Hauban (construction) French गाई तार Hindi Tali penegar ID Tirante Italian 支線 (建築) Japanese
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A guy-wire, guy-line, guy-rope, down guy, or stay, also called simply a guy, is a tensioned cable designed to add stability to a freestanding structure. They are used commonly for ship masts, radio masts, wind turbines, utility poles, and tents. A thin vertical mast supported by guy wires is called a guyed mast. Structures that support antennas are frequently of a lattice construction and are called "towers". One end of the guy is attached to the structure, and the other is anchored to the ground at some distance from the mast or tower base. The tension in the diagonal guy-wire, combined with the compression and buckling strength of the structure, allows the structure to withstand lateral loads such as wind or the weight of cantilevered structures. They are installed radially, usually at equal angles about the structure, in trios and quads. As the tower leans a bit due to the wind force, the increased guy tension is resolved into a compression force in the tower or mast and a lateral force that resists the wind load. For example, antenna masts are often held up by three guy-wires at 120° angles. Structures with predictable lateral loads, such as electrical utility poles, may require only a single guy-wire to offset the lateral pull of the electrical wires, at a spot where the wires change direction.
Conductive guy cables for radio antenna masts may disturb the radiation pattern of the antenna, so their electrical characteristics must be included in the design. Usually this conductive guy cables that otherwise would consume up some of the radiation power and radiate it in some other direction than intended. To avoid this, the guy wire gets broken up into a couple of isolated sections that can not act as antennas on their own due to length differences and not being resonant at the transmission frequency.