 Base feed: mast is fed from Aerial Tuning Unit on right via conductor to top of brown ceramic insulator. On the left there is an earthing switch and a spark gap for lightning protection.
 The Blosenbergturm in Beromünster, Switzerland - a free standing mast radiator insulated against ground A mast radiator (a.k.a. 'radiating tower') is a radio mast or tower in which the whole structure works as an antenna. This is commonly used for transmitters operating at VLF, LF and MF, in particular those used for broadcasting. ImageMetadata File history File links Download high resolution version (1944x2592, 678 KB) Photo of small, typical mast radiator at Shrewsbury MF transmitter, owned by Crown Castle UK, taken by User:spliced 15 August 2005. ...
ImageMetadata File history File links Download high resolution version (1944x2592, 678 KB) Photo of small, typical mast radiator at Shrewsbury MF transmitter, owned by Crown Castle UK, taken by User:spliced 15 August 2005. ...
ImageMetadata File history File links Download high resolution version (2592x1944, 1197 KB) Photo of base feed arrangement for mast radiator at Shrewsbury MF transmitter, owned by Crown Castle UK, taken by User:spliced 15 August 2005. ...
ImageMetadata File history File links Download high resolution version (2592x1944, 1197 KB) Photo of base feed arrangement for mast radiator at Shrewsbury MF transmitter, owned by Crown Castle UK, taken by User:spliced 15 August 2005. ...
Image File history File links Download high resolution version (2000x3008, 3887 KB) Summary Blosenbergturm, Beromünster. ...
Image File history File links Download high resolution version (2000x3008, 3887 KB) Summary Blosenbergturm, Beromünster. ...
Masts of the Rugby VLF transmitter in England Radio masts and towers are, typically, tall structures designed to support antennas (also known as aerials in the UK) for telecommunications and broadcasting, including television. ...
Very low frequency or VLF refers to radio frequencies (RF) in the range of 3 to 30 kHz. ...
Low Frequency or LF (sometimes called longwave) refers to Radio Frequencies (RF) in the range of 30-300 kHz. ...
Mediumwave radio transmissions (sometimes called Medium frequency or MF) are those between the frequencies of 300 kHz and 3000 kHz. ...
This article does not cite its references or sources. ...
Design considerations
Design Most mast radiators are built as guyed masts insulated against ground. Steel lattice masts, of triangular cross-section, are the most common type. Square lattice masts and tubular masts are also sometimes used.
Free-standing towers are also used as radiating structures. These towers can have a triangular or a square cross section. One of the best-known radiating towers is the Blosenbergturm in Beromünster. The Blosenbergturm is a transmitting tower in Beromünster, Canton of Lucerne, Switzerland, built in 1937 for the German radio station DRS and sending at a AM frequency of 531 kHz. ...
Beromünster is a town in Switzerland. ...
Concrete towers are not suitable for insulation, because of their enormous weight, exceeding the weight of guyed masts and lattice masts in an order of at least 10.
However masts of glass fibre are sometimes used for some small constructions.
Mast height The ideal height of a mast radiator depends 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 in the range between one sixth and five eighths of the wavelength, with favourite values at the quarter or the half of the radiated wavelength. This is not always possible. In which case, masts with a loading coil, 'capacity hat' or similar loading arrangement must be used. Rough plot of Earths atmospheric transmittance (or opacity) to various wavelengths of electromagnetic radiation, including radio waves. ...
Demographics is a shorthand term for population characteristics. Demographics include age, income, mobility (in terms of travel time to work or number of vehicles available), educational attainment, home ownership, employment status, and even location. ...
Longwave radio frequencies are those below 500 kHz, which correspond to wavelengths longer than 600 meters. ...
Mediumwave radio transmissions (sometimes called Medium frequency or MF) are those between the frequencies of 300 kHz and 3000 kHz. ...
The height of the mast determines the radiation properties. For high power transmitters in the MW range, masts with heights around half of the radiated wavelength are preferred because they focus the radiated power better to the ground than structures with heights of quarter wavelengths, which are preferred of economical reasons for low power medium wave transmitters. A focus of radiated power towards the ground is much desired on frequencies below 3 megahertz, because groundwave propagation is very stable. The usage of masts longer than fifth eights of the wavelength is normally not done, because these masts show bad vertical radiation patterns. So the heights of masts for mediumwave transmitters do normally not exceed the 300 metre level. For longwave transmitters, however, the construction of masts with heights of half-wave wavelength is, because of economical reasons (and perhaps problems with the flight safety), in most cases impossible. The only so far realized radio mast for longwave with a height of the half length of the radiated wavelength was the Warszawa Radio Mast at Konstantynow, Poland. For frequencies below longwave the masts have to be electrically enlarged by loading coils or capacity hats on the top, because the required heights for masts of even quarter wave length are too high. MegaHertz (MHz) is the name given to one million (106) Hertz, a measure of frequency. ...
Longwave radio frequencies are those below 500 kHz, which correspond to wavelengths longer than 600 meters. ...
Longwave radio frequencies are those below 500 kHz, which correspond to wavelengths longer than 600 meters. ...
The Warsaw radio mast in Konstantynów The Warsaw radio mast was the tallest structure ever built; however, it only existed from 1974 to 1991. ...
Konstantynów is a city in Poland, corporated in 1924, but originally founded in the 1820s by a landowner who had planned to build a textile industry there. ...
In electronics, a loading coil is a coil (inductor) that does not provide coupling to any other circuit, but is inserted in a circuit to increase its inductance. ...
Feed arrangements There are two ways of feeding a mast radiator from a transmitter: - Base feed: the mast is supported on an insulator, and the transmitter is connected to the mast just above it;
- Shunt feed: the mast is grounded and the transmitter feeds it via a wire connected to the mast part way up. (This is a similar approach, on a larger scale, to the 'gamma match' popular among radio amateurs for VHF and UHF antennas.)
- Multiple feed: the structure is divided into two (or more) sections with insulators between, each independently fed. This co-linear arrangement enhances low-angle (ground wave) radiation and reduces high-angle (sky wave) radiation. This increases the distance to the 'mush zone' where the ground wave and sky wave are at similar strength at night. This type of antenna is known as an anti-fading or fading reducing aerial.
Amateur radio, commonly called ham radio, is a hobby enjoyed by many people throughout the world (as of 2004 about 3 million worldwide, 70,000 in Germany, 5,000 in Norway, 57,000 in Canada, and 700,000 in the USA). ...
A fading reducing aerial is a transmission aerial for long- and mediumwave with a flat radiation pattern in order to push the area of fading far away from the transmitter site. ...
Ancillary connections A mast radiator may need various electrical connections other than the main RF one. Such connections include static drain chokes for lightning protection, power supplies for aircraft warning lamps, and coaxial feeders for ancillary antennas mounted on the mast. A variety of techniques are used to 'isolate' these connections at the main RF frequency, such as chokes, parallel tuned circuits and coupling loops, on a base-fed mast. On a shunt-fed mast, where the base is grounded, no such measures are necessary. A Choke is an inductor designed to have a high reactance to a particular frequency when used in a signal-carrying circuit. ...
Left: Series / Right: Parallel Arrows indicate direction of current flow. ...
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