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Feed Horn
A feed horn (or feedhorn) is a small horn antenna used to couple a waveguide to e.g. a parabolic dish antenna or offset dish antenna for reception or transmission of microwave. A typical application is the use for satellite television reception with a satellite dish. In that case the feed horn can either be a separate part used together with e.g. a "low-noise block downconverter" (LNB), or more typically today is integrated into a "low-noise block feedhorn" (LNBF). Principle of operation The feed horn minimizes the mismatch loss between the antenna and the waveguide. If a simple open-ended waveguide would be used, without the horn, the sudden end of the conductive walls causes an abrupt impedance change at the aperture, between the wave impedance in the waveguide and the impedance of free space (see horn antenna for more details). When used with a offset, parabolic or lens antenna, the phase center of the horn is placed at the focal point of the reflector. The characteris ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hughes Direcway LNB
Hughes may refer to: People * Hughes (surname) * Hughes (given name) Places Antarctica * Hughes Range (Antarctica), Ross Dependency * Mount Hughes, Oates Land * Hughes Basin, Oates Land * Hughes Bay, Graham Land * Hughes Bluff, Victoria Land * Hughes Glacier, Victoria Land * Hughes Island, Victoria Land * Hughes Peninsula, Ellsworth Land * Hughes Point, Ellsworth Land Australia * Division of Hughes, an electoral district * Hughes, Australian Capital Territory, a suburb of Canberra * Hughes, Northern Territory, a rural locality United States * Hughes, Alaska, a city * Hughes, Arkansas, a city * Hughes, Iowa, a ghost town * Hughes, Wisconsin, a town * Hughes County, Oklahoma * Hughes County, South Dakota * Hughes Lake (California) * Hughes Mountain, Missouri * Hughes River (Virginia) * Hughes River (West Virginia) Other * Hughes, Santa Fe, Argentina, a town * Hughes Range (British Columbia), Canada * Hughes Reef, South China Sea * 1878 Hughes, an asteroid Businesses * Ba ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Phase Center
In antenna design theory, the phase center is the point from which the electromagnetic radiation spreads spherically outward, with the phase of the signal being equal at any point on the sphere. Apparent phase center is used to describe the phase center in a limited section of the radiation pattern. If it is used in the context of an antenna array An antenna array (or array antenna) is a set of multiple connected antennas which work together as a single antenna, to transmit or receive radio waves. The individual antennas (called ''elements'') are usually connected to a single receiver ..., one has to define a reference point from which the basevectors of the single elements are referred to. The phase center may vary, depended on the beamforming algorithm. It produces the weight vector, that may vary over time depending on the geometrical setup as well as the receive conditions. References * J. D. Dyson, “Determination of the Phase Center and Phase Patterns of Antennas, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Communications Satellite
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. Communications satellites are used for television, telephone, radio, internet, and military applications. Many communications satellites are in geostationary orbit above the equator, so that the satellite appears stationary at the same point in the sky; therefore the satellite dish antennas of ground stations can be aimed permanently at that spot and do not have to move to track the satellite. Others form satellite constellations in low Earth orbit, where antennas on the ground have to follow the position of the satellites and switch between satellites frequently. The high frequency radio waves used for telecommunications links travel by line of sight and so are obstructed by the curve of the Earth. The purpose of communications sate ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Block Upconverter
{{Antennas, components A block upconverter (BUC) is used in the transmission (uplink) of satellite signals. It converts a band of frequencies from a lower frequency to a higher frequency. Modern BUCs convert from the L band to Ku band, C band and Ka band. Older BUCs convert from a 70 MHz intermediate frequency (IF) to Ku band or C band. Most BUCs use phase-locked loop local oscillators and require an external 10 MHz frequency reference to maintain the correct transmit frequency. BUCs used in remote locations are often 2 or 4 W in the Ku band and 5 W in the C band. The 10 MHz reference frequency is usually sent on the same feedline as the main carrier. Many smaller BUCs also get their direct current (DC) over the feedline, using an internal DC block. BUCs are generally used in conjunction with low-noise block converters (LNB). The BUC, being an up-converting device, makes up the "transmit" side of the system, while the LNB is the down-converting d ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Very-small-aperture Terminal
A very-small-aperture terminal (VSAT) is a two-way satellite ground station with a dish antenna that is smaller than 3.8 meters. The majority of VSAT antennas range from 75 cm to 1.2 m. Bit rates, in most cases, range from 4 kbit/s up to 16 Mbit/s. VSATs access satellites in geosynchronous orbit or geostationary orbit to relay data from small remote Earth stations (terminals) to other terminals (in mesh topology) or master Earth station "hubs" (in star topology). VSATs are used to transmit narrowband data (e.g., point-of-sale transactions using credit cards, polling or RFID data, or SCADA), or broadband data (for the provision of satellite Internet access to remote locations, VoIP or video). VSATs are also used for transportable, on-the-move (utilising phased array antennas) or mobile maritime communications. History The concept of the geostationary orbit was originated by Russian theorist Konstantin Tsiolkovsky, who wrote articles on space travel around the beginning of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Satellite Internet Access
Satellite Internet access is Internet access provided through communication satellites. Modern consumer grade satellite Internet service is typically provided to individual users through geostationary satellites that can offer relatively high data speeds, with newer satellites using to achieve downstream data speeds up to 506 Mbit/s. In addition, new satellite internet constellations are being developed in low-earth orbit to enable low-latency internet access from space. History Following the launch of the first satellite, Sputnik 1, by the Soviet Union in October 1957, the US successfully launched the Explorer 1 satellite in 1958. The first commercial communications satellite was Telstar 1, built by Bell Labs and launched in July 1962. The idea of a geosynchronous satellite—one that could orbit the Earth above the equator and remain fixed by following the Earth's rotation—was first proposed by Herman Potočnik in 1928 and popularised by the science fiction author Art ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Satellite News Gathering
Electronic news-gathering (ENG) or electronic journalism (EJ) is usage of electronic video and audio technologies by reporters to gather and present news instead of using film cameras. The term was coined during the rise of videotape technology in the 1970s. ENG can involve anything from a single reporter with a single professional video camera, to an entire television crew taking a truck on location. Beginnings Shortcomings of film The term ENG was created as television news departments moved from film-based news-gathering to electronic field production technology in the 1970s. Since film requires chemical processing before it can be viewed and edited, it generally took at least an hour from the time the film arrived back at the television station or network news department until it was ready to be broadcast. Film editing was done by hand on what was known as " color reversal" film, usually Kodak Ektachrome, meaning there were no negatives. Color reversal film had replace ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Satellite Uplink
Satellite link is – according to ''article 1.113'' of the International Telecommunication Union's (ITU) ITU Radio Regulations (RR)ITU Radio Regulations, Section IV. Radio Stations and Systems – Article 1.113, definition: ''satellite link'' – defined as «''A radio link between a transmitting earth station and a receiving earth station through one satellite. A satellite link comprises one up-link and one down-link In a telecommunications network, a link is a communication channel that connects two or more devices for the purpose of data transmission. The link may be a dedicated physical link or a virtual circuit that uses one or more physical links or shar ...''.» Each ''station'' shall be classified by the ''service'' in which it operates permanently or temporarily. ;See also: References / sources International Telecommunication Union (ITU){{Radio station ITU Radio stations and systems ITU ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Coaxial Cable
Coaxial cable, or coax (pronounced ) is a type of electrical cable consisting of an inner conductor surrounded by a concentric conducting shield, with the two separated by a dielectric ( insulating material); many coaxial cables also have a protective outer sheath or jacket. The term ''coaxial'' refers to the inner conductor and the outer shield sharing a geometric axis. Coaxial cable is a type of transmission line, used to carry high-frequency electrical signals with low losses. It is used in such applications as telephone trunk lines, broadband internet networking cables, high-speed computer data busses, cable television signals, and connecting radio transmitters and receivers to their antennas. It differs from other shielded cables because the dimensions of the cable and connectors are controlled to give a precise, constant conductor spacing, which is needed for it to function efficiently as a transmission line. Coaxial cable was used in the first (1858) and followin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
RF Front End
RF is an abbreviation for radio frequency. Rf or RF may also mean: Arts and entertainment * ''Red Faction (series)'', a series of revolution video games * Rinforzando, , in music notation * '' RF Online'', an online RPG made by CCR Businesses * Aero K, IATA code (2020—present) * Florida West International Airways, IATA code (1984—2017) * Regions Financial Corporation, NYSE stock symbol Government and military * France (''République française'') * Russian Federation * Rhodesian Front, former political party in Rhodesia Biology and medicine * Rheumatic fever, an inflammatory disease * Release factors RF1, RF2, RF3, proteins * Reticular formation, in the brainstem * Rheumatoid factor, an antibody * Receptive field, the response characteristic of a neuron * Respiratory failure * Risk factor Other uses in science and technology * Representative fraction * Retardation factor in a chromatographic system * Radiative forcing, the change in energy flux in the atmosphere caused ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Satellite TV
Satellite television is a service that delivers television programming to viewers by relaying it from a communications satellite orbiting the Earth directly to the viewer's location. The signals are received via an outdoor parabolic antenna commonly referred to as a satellite dish and a low-noise block downconverter. A satellite receiver then decodes the desired television program for viewing on a television set. Receivers can be external set-top boxes, or a built-in television tuner. Satellite television provides a wide range of channels and services. It is usually the only television available in many remote geographic areas without terrestrial television or cable television service. Modern systems signals are relayed from a communications satellite on the X band (8–12 GHz) or Ku band (12–18 GHz) frequencies requiring only a small dish less than a meter in diameter. The first satellite TV systems were an obsolete type now known as television receive-only. These s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Beamwidth
The beam diameter or beam width of an electromagnetic beam is the diameter along any specified line that is perpendicular to the beam axis and intersects it. Since beams typically do not have sharp edges, the diameter can be defined in many different ways. Five definitions of the beam width are in common use: D4σ, 10/90 or 20/80 knife-edge, 1/e2, FWHM, and D86. The beam width can be measured in units of length at a particular plane perpendicular to the beam axis, but it can also refer to the angular width, which is the angle subtended by the beam at the source. The angular width is also called the beam divergence. Beam diameter is usually used to characterize electromagnetic beams in the optical regime, and occasionally in the microwave regime, that is, cases in which the aperture from which the beam emerges is very large with respect to the wavelength. Beam diameter usually refers to a beam of circular cross section, but not necessarily so. A beam may, for example, have an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
