A
guy-wire or
guy-rope, also known as simply a
guy, is a tensioned cable designed to add stability to structures (frequently
ship mastsThe mast of a sailing vessel is a tall, vertical, or near vertical, spar, or arrangement of spars, which supports the sails. Large ships have several masts, with the size and configuration depending on the style of ship...
,
radio mastsRadio masts and towers are, typically, tall structures designed to support antennas for telecommunications and broadcasting, including television. They are among the tallest man-made structures...
, wind turbines,
utility poleA utility pole is a pole used to support overhead power lines and various other public utilities, such as cable, fibre optic cable, and related equipment such as transformers and street lights. It can be referred to as a telephone pole, power pole, hydro pole, telegraph pole, or telegraph post,...
s, and
tentA tent is a shelter consisting of sheets of fabric or other material draped over or attached to a frame of poles or attached to a supporting rope. While smaller tents may be free-standing or attached to the ground, large tents are usually anchored using guy ropes tied to stakes or tent pegs...
s). One end of the cable is attached to the structure, and the other is anchored to the ground at a distance from the structure's base. They are often configured radially (equally spaced about the structure) in trios, quads (pairs of pairs) or other sets. This allows the tension of each guy-wire to offset the others. For example, roof
antennasAn antenna is an electrical device which converts electric currents into radio waves, and vice versa. It is usually used with a radio transmitter or radio receiver...
are sometimes held up by three guy-wires.
On some very high structures flight-safety markers on the guys themselves are necessary. Shorter, sturdier structures, such as electrical utility poles, may require only a single guy-wire to offset the pull of the electrical wires.
For chimneys and masts for
VHFVery high frequency is the radio frequency range from 30 MHz to 300 MHz. Frequencies immediately below VHF are denoted High frequency , and the next higher frequencies are known as Ultra high frequency...
-/
UHFUltra-High Frequency designates the ITU Radio frequency range of electromagnetic waves between 300 MHz and 3 GHz , also known as the decimetre band or decimetre wave as the wavelengths range from one to ten decimetres...
-transmissions or non-transmission use, only the mechanical properties of the guys are important. This is not the case for mast antennas, for masts with aerials for
VLF225px|thumb|right|A VLF receiving antenna at [[Palmer Station]], Antarctica, operated by Stanford UniversityVery low frequency or VLF refers to radio frequencies in the range of 3 kHz to 30 kHz. Since there is not much bandwidth in this band of the radio spectrum, only the very simplest signals...
,
LFLow frequency or low freq or LF refers to radio frequencies in the range of 30 kHz–300 kHz. In Europe, and parts of Northern Africa and of Asia, part of the LF spectrum is used for AM broadcasting as the longwave band. In the western hemisphere, its main use is for aircraft beacon,...
,
MFMedium wave is the part of the medium frequency radio band used mainly for AM radio broadcasting. For Europe the MW band ranges from 526.5 kHz to 1606.5 kHz...
, and
SWShortwave radio refers to the upper MF and all of the HF portion of the radio spectrum, between 1,800–30,000 kHz. Shortwave radio received its name because the wavelengths in this band are shorter than 200 m which marked the original upper limit of the medium frequency band first used...
or for masts situated close to such aerials.
Sailing
A guy is a term for a line (
ropeA rope is a length of fibres, twisted or braided together to improve strength for pulling and connecting. It has tensile strength but is too flexible to provide compressive strength...
) attached to and intended to control the end of a spar on a sailboat. On a modern
sloopA sloop is a sail boat with a fore-and-aft rig and a single mast farther forward than the mast of a cutter....
-rigged
sailboatA sailboat or sailing boat is a boat propelled partly or entirely by sails. The term covers a variety of boats, larger than small vessels such as sailboards and smaller than sailing ships, but distinctions in the size are not strictly defined and what constitutes a sailing ship, sailboat, or a...
with a symmetric
spinnakerA spinnaker is a special type of sail that is designed specifically for sailing off the wind from a reaching course to a downwind, i.e. with the wind 90°–180° off the bow. The spinnaker fills with wind and balloons out in front of the boat when it is deployed, called flying. It is constructed of...
, the
spinnaker poleA spinnaker pole is a spar used in sailboats to help support and control a variety of headsails, particularly the spinnaker. However, it is also used with other sails, such as genoas and jibs, when sailing downwind with no spinnaker hoisted...
is the spar most commonly controlled by one or more guys.
Guys for mast antennas
Special attention must be paid to guy-wires of mast antennas. Guys of conductive materials such as metals and that are longer than one-fifth of the radiated
wavelengthIn physics, the wavelength of a sinusoidal wave is the spatial period of the wave—the distance over which the wave's shape repeats.It is usually determined by considering the distance between consecutive corresponding points of the same phase, such as crests, troughs, or zero crossings, and is a...
can have a strong influence of the
radiation patternIn the field of antenna design the term radiation pattern most commonly refers to the directional dependence of the strength of the radio waves from the antenna or other source ....
, especially when used as a mast antenna or carrying an aerial for VLF, LF, MF, and SW. Guy wires also sometimes interfere when situated close to such a site.
When
steel cablethumb|Steel wire rope Wire rope is a type of rope which consists of several strands of metal wire laid into a helix. Initially wrought iron wires were used, but today steel is the main material used for wire ropes....
is used, the guys are divided by
strain insulatorA strain insulator is an insulator that provides both large electrical insulation and a large load-bearing capacity. Strain insulators were first used in telegraph systems to isolate the signal wire from ground while still supporting the wire...
s into multiple sections, each smaller than one-fifth of radiated wavelength.
PorcelainPorcelain is a ceramic material made by heating raw materials, generally including clay in the form of kaolin, in a kiln to temperatures between and...
is often used for these insulators. The individual sections of the guys can develop large charges of
static electricityStatic electricity refers to the build-up of electric charge on the surface of objects. The static charges remain on an object until they either bleed off to ground or are quickly neutralized by a discharge. Static electricity can be contrasted with current electricity, which can be delivered...
, especially on very tall masts. The
voltageVoltage, otherwise known as electrical potential difference or electric tension is the difference in electric potential between two points — or the difference in electric potential energy per unit charge between two points...
caused by this static electricity can be several times larger than that generated by the transmitter. In order to avoid dangerous and unpredictable discharges, the insulators must be designed to withstand this high voltage, which results at tall masts in over-dimensioned backstage insulators. At each backstage insulator, a
lightning arrestorA lightning rod or lightning conductor is a metal rod or conductor mounted on top of a building and electrically connected to the ground through a wire, to protect the building in the event of lightning...
in the form of an arc gap (and often additionally an arrestor) is required for the purpose of over-voltage protection in case of
lightningLightning is an atmospheric electrostatic discharge accompanied by thunder, which typically occurs during thunderstorms, and sometimes during volcanic eruptions or dust storms...
strikes. The insulators and arrestors must be maintained carefully, because an insulator failure can result in a mast collapse.
Some newer mast antennas are fitted with insulators at the mast construction and are
groundedIn electrical engineering, ground or earth may be the reference point in an electrical circuit from which other voltages are measured, or a common return path for electric current, or a direct physical connection to the Earth....
via coils located near each ground anchor. In some cases it is possible to ground the guys directly at the anchor blocks. This is only possible if the guys do not disturb the radiation pattern of the mast antenna.
Guys grounded via a coil or directly have the advantage that maintenance is easier, because all parts requiring maintenance are at the mast and at the anchor basement and that the insulators must only withstand the maximum transmission voltage.
On some mast antennas guys of non-conductive
polymerA polymer is a large molecule composed of repeating structural units. These subunits are typically connected by covalent chemical bonds...
s are used. Although these guys alleviate some of the problems associated with mast antennas they are rarely used as they are not as durable and long-lasting as metal guys.
On antennas for long-wave and VLF, the guys may serve an electrical function, either for
capacitive lengthingIn electronics, capacitive coupling is the transfer of energy within an electrical network by means of the capacitance between circuit nodes. This coupling can have an intentional or accidental effect...
of the mast or for feeding the mast with the radiation power. In these cases, the guys are fixed without an insulator on the mast, but there is at least one insulator in the guy if necessary. If guys are used for feeding the mast with high frequency power it is often possible to use a grounded mast. The power to the guys is fed via conductor ropes running from the tuning unit to the feed point on the guys.
Crane operation
When operating a
craneA crane is a type of machine, generally equipped with a hoist, wire ropes or chains, and sheaves, that can be used both to lift and lower materials and to move them horizontally. It uses one or more simple machines to create mechanical advantage and thus move loads beyond the normal capability of...
, guy wires known as
tag lines may be connected to unwieldy payloads, allowing ground crew to control rotation and swaying while maintaining a safe distance.
Guyed structures
Historically, guyed structures have been some of the
tallest man-made structures in the world. There are also many structures which consist of a free standing bottom and a guyed top. These are either
partially guyed towerA partially guyed tower is a tower structure which consists of a free-standing basement, in most cases of concrete or of lattice steel with a guyed mast on the top. The anchor basements of the guyed mast can be on the top of the tower or on the ground.-Use:...
s or
additionally guyed towerAn additionally guyed tower is a free-standing tower, which is also additionally guyed.An additional guying can be temporarily or permanently. Temporarily additional guying is used when work on static relevant parts of the tower is done....
s, the latter of which may be used temporarily to support tall buildings during their construction.
See also
- Guy (sailing)
A guy is a term for a line attached to and intended to control the end of a spar on a sailboat. On a modern sloop-rigged sailboat with a symmetric spinnaker, the spinnaker pole is the spar most commonly controlled by one or more guys.There are two primary types of guys used to control a...
- Radio masts and towers
Radio masts and towers are, typically, tall structures designed to support antennas for telecommunications and broadcasting, including television. They are among the tallest man-made structures...
- Soil kite
A kite has two parts—wing and tether. The tether is tensed; the wing converts the tension to lift and drag by interacting with a stream of material; the kite flies or deflects away from the relative direction of the ambient stream's material. When the ambient material is air, an air kite is...
- Strain insulator
A strain insulator is an insulator that provides both large electrical insulation and a large load-bearing capacity. Strain insulators were first used in telegraph systems to isolate the signal wire from ground while still supporting the wire...
- Turnbuckle
A turnbuckle, stretching screw or bottlescrew is a device for adjusting the tension or length of ropes, cables, tie rods, and other tensioning systems. It normally consists of two threaded eyelets, one screwed into each end of a small metal frame, one with a left-hand thread and the other with a...
- Shackle
A shackle, also known as a gyve, is a U-shaped piece of metal secured with a clevis pin or bolt across the opening, or a hinged metal loop secured with a quick-release locking pin mechanism...
- Ferrule
A ferrule is a name for types of metal objects, generally used for fastening, joining, or reinforcement...