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Encyclopedia > Satellite dish
Sky Digital "mini-dish"
Sky Digital "mini-dish"
Astro's "mini-dish".
Astro's "mini-dish".
Special dish for up to 16 satellite positions (Ku-band)
Special dish for up to 16 satellite positions (Ku-band)
Satellite dish antenna for C-Band
Satellite Dishes installed on an apartment complex

A satellite dish is a type of parabolic antenna designed with the specific purpose of transmitting signals to and/or receiving from satellites. A satellite dish is a particular type of microwave antenna. Satellite dishes come in varying sizes and designs, and are most commonly used to receive satellite television. Many of the offset type of satellite dishes are sections of a larger parabolic dish. Image File history File links Sky_minidish. ... Image File history File links Sky_minidish. ... Sky Digital is the brand name for British Sky Broadcastings digital satellite television service, transmitted from SES Astra satellites located at 28. ... Image File history File linksMetadata Download high-resolution version (2272x1704, 1087 KB)Image of an Astro satellite dish which was taken myself. ... Image File history File linksMetadata Download high-resolution version (2272x1704, 1087 KB)Image of an Astro satellite dish which was taken myself. ... Download high resolution version (1323x1895, 67 KB) Wikipedia does not have an article with this exact name. ... Download high resolution version (1323x1895, 67 KB) Wikipedia does not have an article with this exact name. ... From the Politehnica University - Bucharest, Romania File history Legend: (cur) = this is the current file, (del) = delete this old version, (rev) = revert to this old version. ... From the Politehnica University - Bucharest, Romania File history Legend: (cur) = this is the current file, (del) = delete this old version, (rev) = revert to this old version. ... Image File history File linksMetadata Download high-resolution version (3456x2304, 4400 KB) Photo taken of Satellite Dishes in San Jose, CA, by Brian Seeling Katt in August of 2006. ... Image File history File linksMetadata Download high-resolution version (3456x2304, 4400 KB) Photo taken of Satellite Dishes in San Jose, CA, by Brian Seeling Katt in August of 2006. ... The Parabolic antenna is a high-gain, reflector antenna used for radio, television and data communications, and also for radiolocation (RADAR), on the UHF and SHF frequencies. ... An Earth observation satellite, ERS 2 For other uses, see Satellite (disambiguation). ... This page is about the radiation; for the appliance, see microwave oven. ... Artists impression of a Boeing 601 satellite, as configured for digital television transmission by SES Astra Satellite television is television delivered by way of communications satellites, as compared to conventional terrestrial television and cable television. ...


The parabolic shape of a dish reflects the signal to the dish’s focal point. Mounted on brackets at the dish's focal point is a device called a feedhorn. This feedhorn is essentially the front-end of a waveguide that gathers the signals at or near the focal point and 'conducts' them to a low-noise block downconverter or LNB. The LNB converts the signals from electromagnetic or radio waves to electrical signals and shifts the signals from the downlinked C-band and/or Ku-band to the L-band range. Direct broadcast satellite dishes use an LNBF, which integrates the feedhorn with the LNB. (A new form of omnidirectional satellite antenna, which does not use a directed parabolic dish and can be used on a mobile platform such as a vehicle was announced by the University of Waterloo. [1]) A parabola A parabola (from the Greek: παραβολή) is a conic section generated by the intersection of a cone, and a plane tangent to the cone or parallel to some plane tangent to the cone. ... In satellite dish and antenna design parlance, a feedhorn (or feed horn) is a horn antenna used to convey radio waves between the transceiver (transmitter and/or receiver) and the reflector. ... Look up waveguide in Wiktionary, the free dictionary. ... A low-noise block converter (LNB, for low-noise block, or sometimes LNC, for low-noise converter) is used in communications satellite (usually broadcast satellite) reception. ... Electromagnetic radiation or EM radiation is a combination (cross product) of oscillating electric and magnetic fields perpendicular to each other, moving through space as a wave, effectively transporting energy and momentum. ... L band (20-cm radar long-band) is a portion of the microwave band of the electromagnetic spectrum ranging roughly from 0. ... In satellite dish and antenna design parlance, a feedhorn (or feed horn) is a horn antenna used to convey radio waves between the transceiver (transmitter and/or receiver) and the reflector. ... The University of Waterloo (also referred to as UW, UWaterloo, or Waterloo) is a medium-sized research-intensive public university in the city of Waterloo, Ontario, Canada. ...


Modern dishes intended for home television use are generally 43 cm (18 in) to 80 cm (31 in) in diameter, and are fixed in one position, for Ku-band reception from one orbital position. Prior to the existence of Direct broadcast satellite services, home users would generally have a motorised C-band satellite dish of up to 3 metres in diameter for reception of channels from different satellites. Overly small dishes can still cause problems, however, including rain fade and interference from adjacent satellites. A centimetre (American spelling centimeter, symbol cm) is a unit of length that is equal to one hundredth of a metre, the current SI base unit of length. ... An inch (plural: inches; symbol or abbreviation: in or, sometimes, ″ - a double prime) is the name of a unit of length in a number of different systems, including English units, Imperial units, and United States customary units. ... DIAMETER is an AAA protocol (Authentication, Authorization and Accounting) succeeding its predecessor RADIUS. // The name is a pun on the RADIUS protocol, which is the predecessor (a diameter is twice the radius). ... This article or section contains information that has not been verified and thus might not be reliable. ... Direct broadcast satellite (DBS) is a term used to refer to satellite television broadcasts intended for home reception, also referred to as direct-to-home signals. ... C band (compromise band) is a portion of electromagnetic spectrum in the microwave range of frequencies ranging from 4 to 6 GHz. ... In satellite communications, rain fade refers to the absorption of a microwave Radio Frequency (RF) signal by rain or snow, and is especially prevalent in frequencies above 11 GHz. ...


Motorised satellite dishes are still popular with enthusiasts. There are three competing standards, which often are all supported by a set-top box, DiSEqC, USALS, and 36v positioners. They can only supply one receiver. DiSEqC switch DiSEqC (Digital Satellite Equipment Control) is a special communication protocol for use between a satellite receiver and a device such as a multi-dish switch or a small dish antenna rotor. ... Universal Satellites Automatic Location System (USALS), also known (unofficially) as , Go X or Go to XX is special program found in digital satellite receivers that automatically creates a list of available satellite positions in a motorised satellite dish setup. ...


A common misconception is that the LNBF (low-noise block/feedhorn), the device at the front of the dish, receives the signal directly from the atmosphere. See, for instance, this BBC News 24 [2] countdown that shows a "red data stream" being received by the LNBF directly instead of being beamed to the dish, which because of its parabolic shape will collect the signal into a smaller area and deliver it to the LNBF. A low-noise block converter (LNB, for low-noise block, or sometimes LNC, for low-noise converter) is used in communications satellite (usually broadcast satellite) reception. ... BBC News 24 is the BBCs 24 hour rolling news television channel in the United Kingdom. ...


In Europe the frequencies used by DBS services are 10.7 - 12.75 GHz on two polarisations H and V. This range is divided into a 'low band' with 10.7 - 11.7 GHz, and a 'high band' with 11.7 - 12.75 GHz. This results in four frequency bands, each with a bandwidth of about 1 GHz. In the LNB they become down converted to 950 - 2150 MHz, which is the frequency range allocated for the satellite service on the coaxial cable between LNBF and receiver. Lower frequencies are allocated to Cable and Terrestrial TV, FM radio, etc. Only one of these frequency bands fits on the coaxial cable, so each of these bands needs a separate cable from the LNBF to a switching matrix or the receiver needs to select one of the 4 bands at a time.


In a single receiver residential installation there is a single cable from receiver to LNB and the receiver uses different power supply voltages (14/18V) and pilot tones (22 kHz) to instruct the LNB to select one of the 4 bands. In larger installations each band is given its own cable, so there are 4 cables from the LNB to a switching matrix, which allows the connection of multiple receivers in a star topology using the same signalling method as in a single receiver installation.


The theoretical gain of a dish increases as the frequency increases. The actual gain depends on many factors including surface finish, accuracy of shape, feedhorn matching.


With lower frequencies, C-Band for example, dish designers have a wider choice of materials. The large size of dish required for lower frequencies led to the dishes being constructed from metal mesh on a metal framework. At higher frequencies, mesh type designs are rarer though some designs have used a solid dish with perforations. C band (compromise band) is a portion of electromagnetic spectrum in the microwave range of frequencies ranging from 4 to 6 GHz. ...


The dish is a reflector antenna and almost anything that reflects radio frequencies can be used as a reflector antenna. This has led to dustbin lids, woks and other items being used as "dishes". Coupled with low noise LNBs and the higher transmission power of DTH satellites, it is easier to get a usable signal on some of these "dishes".


Types

  • Individual dishes serving one dwelling: Direct To Home (DTH).
  • Collective dishes, shared by several dwellings: Satellite Master Antenna Television (SMATV) or Communal Antenna Broadcast Distribution (CABD).

See also

Calculating satellite dish direction Home dish installation The view-direction of a satellite dish depends on the dish position on the Earth and on the satellite position in the Clarke belt. ...

External links

Wikimedia Commons has media related to:
Satellite dish (Television)
  • European Commission: The right to use a satellite dish.
  • SatelliteAdviser.com - Get all info on satellite TV dealers in US.

  Results from FactBites:
 
satellite dish: Definition and Much More from Answers.com (2478 words)
Satellite television was not widely available until the 1970s, when cable television stations equipped with satellite dishes received signals that were then sent to subscribers by coaxial cable.
A satellite dish is a type of parabolic antenna designed with the specific purpose of transmitting signals to and/or receiving from satellites.
Modern dishes intended for home television use are generally 43 cm (18") to 80 cm (31") in diameter, and are fixed in one position, for Ku-band reception from one orbital position.
  More results at FactBites »

 
 

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