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Masts are among the tallest man-made structures. While the structure type is commonly used on sailing ships as support for sails, they are also used for communication equipment such as radio antenna's radio mast. On land they are also used for communication, usually as a very tall radio tower, or sometimes for microwave communication arrays.
Shorter masts often need no guy lines and usually end up being referred to as a pole, such as a telephone pole (though these often have guy lines) or flag poles. Much taller mast structures use the mast term (or when they're on boats as previously mentioned) with exception of some hybrid towers/masts that incorporate elements from both and usually just use the term 'tower'.
In any case, masts offer maximum height for minimum cost and form a integral part of the world's communication infrastructure. Physically masts have a very narrow body that offers vertical support and a series of guy lines under tension that offer lateral support.
The standard mast differs significantly from towers (see List of towers) in rarely being free standing or having any habitable space excluding attached structures at ground level or service ladders/elevators. Observation decks or restaurants are not present, and most masts function as a very large antenna for broadcast organizations. Of course there are many borderline structures that fall in the realm of guyed and non-guyed masts and towers.
Hybrid mast structures such as tower structures that have mast-like elements blur distinctions. Also many large electrical towers or wind-turbine masts are of an unclear classification. The current table data table standards are in flux as to whether it includes electrical towers or other hybrid structures. Many of the can be found on List of towers, however.
- Some borderline cases
- Zendstation Smilde a tall tower with a guyed mast on top (guys go to ground)
- Torre de Collserola a guyed tower, with a guyed mast on top. (tower portion is not free standing).
- Hochspannungsmast of Elbe crossing 2 - a freestanding steel framework tower used as pylon for four circuits of 380 kV. It was built in 1978 and is 745 ft (227 m) high.
A small observation deck on the top of super tall guyed mast, or a one-story building with massive mast on top classified as a structural detail, and things in this vein, can pose huge problems for existing measurement classifications.
Free-standing towers sometimes use the mast term to describe themselves just as guyed masts sometimes call themselves towers.
Masts commonly have the name of the broadcasting designation that uses them, or sometimes of a nearby city or town.
The Warsaw Radio Mast (Warszawa radio mast) was the tallest man-made structure ever made, but it collapsed in 1991 leaving the KVLY/KTHI-TV mast as the next tallest. This includes structures of any type, but does not include things like lines going up to captive balloons or the structures that are the highest above sea level (e.g. a tent on Mount Everest). See world's tallest structures for further analysis.
Towers and buildings with masts on them (that are a hybrid) are in their own list. See List of towers for towers. Note many guyed masts/masts are called towers and numerous towers call themselves masts.
(lists not guaranteed to be accurate or up to date and includes structures traditionally thought of as a mast)(includes up to 2004)
List of masts
Virtually all mast structures are pure guyed masts. There is often crossover in term usage as some skyscraper use the tower term, some towers use the mast term, and ironically 'skyscraper' has some word heritage from references to high sailboat masts.
Top masts are ranked by pinnacle height; for ties, the older building is ranked higher. Most are in the U.S.(for the taller ones), the Warszawa in Poland being a notable exception. The larger number around 2000 ft are the result of special US rules limiting structures and objects that go above 2000 ft (as a result very few things go above this altitude).
The ideal height of a mast as antenna varies depending on transmission frequency, demographics for the location, and terrain. For radio systems in the longwave and mediumwave range the value of the height should be the quarter or the half of the wavelength. This is not always possible. When they are not, masts with roof capacity or other special measures must be used. Radio masts for VLF, LF and MF often act directly as aerials and are therefore often insulated against ground. Electric devices on them are fed via cables running through the coils of a parallel resonance circuit which is switched in parallel to the transmitter output. For transmissions in the VHF and UHF range the value can vary depending on the area to be served. The cost of a tower must be re-couped primarily through advertising on the broadcasts. Things like population density, how far a signal can travel (affected by terrain for line of sight for some kinds of transmission), cost of a higher tower, maintenance cost, etc. — all must be balanced for an ideal tower size. Two shorter towers may be a better option the one taller one, for example, or a higher tower might not be useful if the signal is blocked by terrain nor if all the listeners are in a concentrated area and a higher tower cannot pay for itself.
Once again, the list includes guyed masts, almost exclusively communication masts though a few for other purposes are present. Self-supporting masts are covered as towers under the List of towers, and the borderline cases are mentioned separately (hybrid designs, under water, etc.) elsewhere on this page. (Updated to 2004, not guaranteed to be accurate or up to date) (Destroyed towers are noted)(~160+ in list) (light red tint given to destroyed masts)
Note:
- The Petronius Compliant Tower, an oil platform) at 2100 ft or 640 m (to the top of the spire) is the tallest non-guyed structure in existence but it is mostly underwater (taller than all but the Warsaw radio mast). The CN Tower at 553.33 meters (1,815 feet 4.5 inches) is the tallest non-guyed structure on land, though it's shorter than many of the guyed towers.
See Also
See also:
External Links:
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