A radio telescope is a specialized antenna and radio receiver used to detect radio waves from astronomical radio sources in the sky. Radio telescopes are the main observing instrument used in radio astronomy, which studies the radio frequency portion of the electromagnetic spectrum emitted by astronomical objects, just as optical telescopes are the main observing instrument used in traditional optical astronomy which studies the light wave portion of the spectrum coming from astronomical objects. Unlike optical telescopes, radio telescopes can be used in the daytime as well as at night.
Very high frequency (VHF) is the ITU designation for the range of radio frequency electromagnetic waves from 30 to 300 megahertz (MHz), with corresponding wavelengths of ten meters to one meter. Frequencies immediately below VHF are denoted high frequency (HF), and the next higher frequencies are known as ultra high frequency (UHF).
A directional antenna or beam antenna is an antenna which radiates or receives greater radio wave power in specific directions. Directional antennas can radiate radio waves in beams, when greater concentration of radiation in a certain direction is desired, or in receiving antennas receive radio waves from one specific direction only. This can increase the power transmitted to receivers in that direction, or reduce interference from unwanted sources. This contrasts with omnidirectional antennas such as dipole antennas which radiate radio waves over a wide angle, or receive from a wide angle.
Super high frequency (SHF) is the ITU designation for radio frequencies (RF) in the range between 3 and 30 gigahertz (GHz). This band of frequencies is also known as the centimetre band or centimetre wave as the wavelengths range from one to ten centimetres. These frequencies fall within the microwave band, so radio waves with these frequencies are called microwaves. The small wavelength of microwaves allows them to be directed in narrow beams by aperture antennas such as parabolic dishes and horn antennas, so they are used for point-to-point communication and data links and for radar. This frequency range is used for most radar transmitters, wireless LANs, satellite communication, microwave radio relay links, satellite phones, and numerous short range terrestrial data links. They are also used for heating in industrial microwave heating, medical diathermy, microwave hyperthermy to treat cancer, and to cook food in microwave ovens.
The Fernsehturm in central Berlin was constructed between 1965 and 1969 by the government of the German Democratic Republic, or East Germany, as both a functional broadcasting facility and a symbol of Communist power.
Tallinn TV Tower is a free-standing structure with an observation deck, built to provide better telecommunication services for the 1980 Moscow Summer Olympics regatta event. It is located near the suburb Pirita, six km north-east of the Tallinn city center. With its 313 m (1030.2 ft), the TV tower is the tallest nonbuilding structure in Tallinn. The tower was officially opened on 11 July 1980. The viewing platform at a height of 170 metres was open to the public until 26 November 2007, when it was closed for renovation. The tower began receiving visitors again on 5 April 2012. The building is administered by the public company Levira and is a member of the World Federation of Great Towers.
Fernsehturm Stuttgart is a 216.61 m (710.7 ft) telecommunications tower in Stuttgart, Germany. It was the first telecommunications tower in the world constructed from reinforced concrete, and it is the prototype for many such towers worldwide. Although controversial at first, it quickly became a well known landmark of Stuttgart and a tourist attraction.
The Fernmeldeturm Nürnberg, the tallest structure in Bavaria, is a telecommunication tower in Nuremberg, southern Germany. Also called the Nürnberger Ei because of its egg-shaped tower basket in a height of 185 metres, it is 292 metres high and was built between 1977 and 1980 according to blueprints by architect Erwin Heinle.
Frohnau is a locality in the Reinickendorf borough of Berlin, Germany. It lies in the extreme northern part of the city. Frohnau is an affluent area characterized by many patrician villas from the early 20th century.
The Richtfunkstelle Berlin-Frohnau was a facility for directional radio services in Frohnau. Before German reunification, the facility served as a microwave transmission link between West Berlin and West Germany.
The Rheinturm is a 240.5-metre-high (789 ft) concrete telecommunications tower in Düsseldorf, capital of the federal state (Bundesland) of North Rhine-Westphalia, Germany. Construction commenced in 1979 and finished in 1981. The Rheinturm carries aerials for directional radio, FM and TV transmitters. It stands 172.5 metres high and houses a revolving restaurant and an observation deck at a height of 168 metres. It is the tallest building in Düsseldorf.
The Brocken Transmitter is a facility for FM- and TV-transmitters on the Brocken, the highest mountain in Northern Germany.
The Feldberg/Taunus transmitter is a facility for FM- and TV-broadcasting and for directional radio services located on the Großer Feldberg, the highest mountain in the Taunus region of Germany.
The Fernmeldeturm Münster or, colloquial: "Fernsehturm" (TV-Tower) is the modern landmark of Münster completed in 1985/86. The 229.5-metre-high (753 ft) tower, which is used for directional services and TV-, VHF- and UHF-transmission is not accessible to the public. The basket of this tower, which carries also the name "Münster 42" has a diameter of 40 metres and is situated at a height of 108 metres.
A broadcast transmitter is an electronic device which radiates radio waves modulated with information content intended to be received by the general public. Examples are a radio broadcasting transmitter which transmits audio (sound) to broadcast radio receivers (radios) owned by the public, or a television transmitter, which transmits moving images (video) to television receivers (televisions). The term often includes the antenna which radiates the radio waves, and the building and facilities associated with the transmitter. A broadcasting station consists of a broadcast transmitter along with the production studio which originates the broadcasts. Broadcast transmitters must be licensed by governments, and are restricted to specific frequencies and power levels. Each transmitter is assigned a unique identifier consisting of a string of letters and numbers called a callsign, which must be used in all broadcasts.
Microwave transmission is the transmission of information by electromagnetic waves with wavelengths in the microwave frequency range of 300 MHz to 300 GHz of the electromagnetic spectrum. Microwave signals are normally limited to the line of sight, so long-distance transmission using these signals requires a series of repeaters forming a microwave relay network. It is possible to use microwave signals in over-the-horizon communications using tropospheric scatter, but such systems are expensive and generally used only in specialist roles.
Gartow-Höhbeck transmitter is a large facility for FM and TV transmission in Lower Saxony, Germany, situated behalf of the communities of Gartow and Höhbeck.
The Bungsberg telecommunications tower, also known as the Fernmeldeturm Schönwalde, is a 179-metre-high telecommunications tower situated on the Bungsberg, a hill which is the highest point in the north German state of Schleswig-Holstein.
The Ochsenkopf Transmitter is a 163 metres (535 ft) radio and TV tower of reinforced concrete, which was built in 1958 on the summit of the 1,024 metres (3,360 ft) Ochsenkopf mountain, the second-highest mountain in the Fichtel Mountains in Northern Bavaria, Germany. The tower replaced a 50 metres (160 ft) guyed steel tube TV mast that collapsed in January 1958 as result of icing. The tower, which is not accessible to the public, has a hyperbolic-shaped basement with five floors for technical equipment. Above it, there are platforms for directional antennas. The antennas for FM-transmission are on the upper part of the concrete tower, those for TV transmission on a steel tube mast on the top.
The Mechelen-Zuid water tower is a 143-metre-high (469 ft), combined water and telecommunications tower constructed in 1978. Since 1979, it has supplied the water to the city of Mechelen, Belgium, while also hosting television and telecommunications aerials. The concrete spire passes through a wide disc holding water fifty metres above the ground. Higher up, a smaller disc supports telecommunications equipment. Topped by a decorative stainless steel tube, it is claimed to be the highest water tower in the world.
