A beam waveguide antenna is a particular type of antenna dish, at which

waveguide A waveguide is a structure that guides waves, such as electromagnetic waves or sound, with minimal loss of energy by restricting the transmission of energy to one direction. Without the physical constraint of a waveguide, wave intensities de ...

s are used to transmit the radio beam between the large steerable dish and the equipment for

reception Reception is a noun form of ''receiving'', or ''to receive'' something, such as art, experience, information, people, products, or vehicles. It may refer to: Astrology * Reception (astrology), when a planet is located in a sign ruled by another p ...

transmission Transmission may refer to: Medicine, science and technology * Power transmission ** Electric power transmission ** Propulsion transmission, technology allowing controlled application of power *** Automatic transmission *** Manual transmission *** ...

, like e.g.

RF power amplifier A radio-frequency power amplifier (RF power amplifier) is a type of electronic amplifier that converts a low-power radio-frequency signal (electrical engineering), signal into a higher-power signal. Typically, RF power amplifiers drive the anten ...

Principle of operation

Beam waveguide antennas are used in large

radio telescope 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 ...

s and

satellite communication A communications satellite is an artificial satellite that relays and amplifies radio telecommunication signals via a transponder; it creates a communication channel between a source transmitter and a receiver at different locations on Earth. C ...

stations as an alternative to the most common parabolic antenna design, the conventional "front fed" parabolic antenna. In front feed, the

antenna feed A radio transmitter or receiver is connected to an antenna which emits or receives the radio waves. The antenna feed system or antenna feed is the cable or conductor, and other associated equipment, which connects the transmitter or receiver w ...

, the small

antenna Antenna ( antennas or antennae) may refer to: Science and engineering * Antenna (radio), also known as an aerial, a transducer designed to transmit or receive electromagnetic (e.g., TV or radio) waves * Antennae Galaxies, the name of two collid ...

that transmits or receives the radio waves reflected by the dish, is suspended at the

focus Focus, or its plural form foci may refer to: Arts * Focus or Focus Festival, former name of the Adelaide Fringe arts festival in South Australia Film *''Focus'', a 1962 TV film starring James Whitmore * ''Focus'' (2001 film), a 2001 film based ...

, in front of the dish. However, this location causes a number of practical difficulties. In high performance systems, complex transmitter and receiver electronics must be located at the feed antenna. This feed equipment usually requires high maintenance; some examples are

water cooling Cooling tower and water discharge of a nuclear power plant Water cooling is a method of heat removal from components and industrial equipment. Evaporative cooling using water is often more efficient than air cooling. Water is inexpensive and non ...

for transmitters and

cryogenic In physics, cryogenics is the production and behaviour of materials at very low temperatures. The 13th IIR International Congress of Refrigeration (held in Washington DC in 1971) endorsed a universal definition of “cryogenics” and “cr ...

cooling for sensitive receivers. With the large dishes used in these systems, the focus is high off the ground, and servicing requires cranes or scaffolds, and outdoor work with delicate equipment high off the ground. Furthermore, the feeds themselves have to be designed to handle outdoor conditions such as rain and large temperature swings, and to work while tipped at any angle. The beam waveguide antenna addresses these problems by locating the feed antenna in a "feed house" at the base of the antenna, instead of in front of the dish. The radio waves collected by the dish are focused into a beam and reflected by metal surfaces in a path through the supporting structure to the stationary feed antenna at the base. The path is complicated because the beam must pass through both axes of the

altazimuth mount An altazimuth mount or alt-azimuth mount is a simple two-axis mount for supporting and rotating an instrument about two perpendicular axes – one vertical and the other horizontal. Rotation about the vertical axis varies the azimuth (compass bea ...

of the antenna, so turning the antenna does not disturb the beam.

History

Beam waveguides, which propagate a microwave beam using a series of reflectors, were proposed as early as 1964. By 1968, there were proposals to handle some of the signal path in pointable antennas by these techniques. By 1970, a fully beam-waveguide approach was proposed for

satellite A satellite or artificial satellite is an object intentionally placed into orbit in outer space. Except for passive satellites, most satellites have an electricity generation system for equipment on board, such as solar panels or radioisotope ...

communication antennas. At first, it was believed the complicated signal path with its multiple reflecting surfaces would result in unacceptable signal loss but further analysis showed the waveguide system could be built with very low losses. The first full scale beam waveguide antenna was the 64 meter antenna at the

Usuda Deep Space Center Usuda Deep Space Center is a facility of the Japan Aerospace Exploration Agency. It is a spacecraft tracking station in Saku, Nagano, opened in October, 1984. The main features of the station are two large beam waveguide antennas, an older 64 ...

, Japan, built in 1984 by the

Japan Aerospace Exploration Agency The is the Japanese national air and space agency. Through the merger of three previously independent organizations, JAXA was formed on 1 October 2003. JAXA is responsible for research, technology development and launch of satellites into orb ...

. After the

Jet Propulsion Lab The Jet Propulsion Laboratory (JPL) is a federally funded research and development center and NASA field center in the City of La Cañada Flintridge, California, United States. Founded in the 1930s by Caltech researchers, JPL is owned by NASA an ...

(JPL) tested this antenna and found it better than their conventional 64-meter antennas, they too switched to this method of construction for all subsequent antennas of their

Deep Space Network The NASA Deep Space Network (DSN) is a worldwide Telecommunications network, network of American spacecraft communication ground segment facilities, located in the United States (California), Spain (Madrid), and Australia (Canberra), that suppo ...

(DSN).

References

{{Reflist Radio frequency antenna types Antennas (radio)