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Satellite Dish
A satellite dish is a dish-shaped type of parabolic antenna designed to receive or transmit information by radio waves to or from a communication satellite. The term most commonly means a dish which receives direct-broadcast satellite television from a direct broadcast satellite in geostationary orbit. History Parabolic or "dish" antennas had been in use as radio telescopes (beginning in 1937) and airplane tracking by the military (during WWII) long before the first artificial satellite was launched in 1957. The term ''satellite dish'' was coined in 1978 during the beginning of the satellite television industry, and came to refer to dish antennas that send and/or receive signals from communications satellites. Taylor Howard of San Andreas, California, adapted an ex-military dish in 1976 and became the first person to receive satellite television signals using it. The first satellite television dishes were built to receive signals on the C-band analog, and were very lar ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Parabolic Antenna
A parabolic antenna is an antenna that uses a parabolic reflector, a curved surface with the cross-sectional shape of a parabola, to direct the radio waves. The most common form is shaped like a dish and is popularly called a dish antenna or parabolic dish. The main advantage of a parabolic antenna is that it has high directivity. It functions similarly to a searchlight or flashlight reflector to direct radio waves in a narrow beam, or receive radio waves from one particular direction only. Parabolic antennas have some of the highest gains, meaning that they can produce the narrowest beamwidths, of any antenna type. In order to achieve narrow beamwidths, the parabolic reflector must be much larger than the wavelength of the radio waves used, so parabolic antennas are used in the high frequency part of the radio spectrum, at UHF and microwave ( SHF) frequencies, at which the wavelengths are small enough that conveniently sized reflectors can be used. Parabolic antennas a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fiberglass
Fiberglass (American English) or fibreglass (English in the Commonwealth of Nations, Commonwealth English) is a common type of fibre-reinforced plastic, fiber-reinforced plastic using glass fiber. The fibers may be randomly arranged, flattened into a sheet called a chopped strand mat, or woven into glass cloth. The plastic Matrix (composite), matrix may be a thermoset polymer matrix—most often based on thermosetting polymers such as epoxy, polyester resin, or vinyl ester resin—or a thermoplastic. Cheaper and more flexible than Carbon-fiber-reinforced polymers, carbon fiber, it is stronger than many metals by weight, non-magnetic, non-conductive, transparent to electromagnetic radiation, can be molded into complex shapes, and is chemically inert under many circumstances. Applications include aircraft, boats, automobiles, bath tubs and enclosures, swimming pools, hot tubs, septic tanks, water tanks, roofing, pipes, cladding, orthopedic casts, surfboards, and external door skins ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bangor Daily News
The ''Bangor Daily News'' is an American newspaper covering a large portion of central and eastern Maine, published six days per week in Bangor, Maine. The ''Bangor Daily News'' was founded on June 18, 1889; it merged with the ''Bangor Whig and Courier'' in 1900. Also known as ''the News'' or ''the BDN'', the paper is published by Bangor Publishing Company, a local family-owned company. It has been owned by the Towle-Warren family for four generations; current publisher Richard J. Warren is the great-grandson of J. Norman Towle, who bought the paper in 1895. Since 2018, it has been the only independently owned daily newspaper in the state. History 19th century The ''Bangor Daily News''s first issue was June 18, 1889; the main stockholder in the publishing company was Bangor shipping and logging businessman Thomas J. Stewart. Upon Stewart's death in 1890, his sons took control of the paper, which was originally a tabloid with "some news, but also plenty of gossip, lurid storie ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
PrimeStar
PrimeStar was an American direct broadcast satellite broadcasting company formed in November 1990 by seven cable television companies including Comcast Corp. and TCI Communications Corp. PrimeStar was the first medium-powered DBS system in the United States but slowly declined in popularity with the arrival of DirecTV in 1994 and Dish Network in 1996. Technology PrimeStar was a medium-powered DBS-style system utilizing FSS technology that used a larger 3-foot (91 cm) satellite dish to receive signals. Broadcast originally in analog, they later converted to digital technology. The system used the DigiCipher 1 system for conditional access control and video compression. The video format was MPEG-2. Primestar's satellite receivers were made by General Instrument. PrimeStar was owned by a consortium of cable television companies who leased equipment to subscribers through the local cable company. The company was in the process of converting to a high-powered DBS ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ku Band
The Ku band () is the portion of the electromagnetic spectrum in the microwave range of frequencies from 12 to 18 gigahertz (GHz). The symbol is short for "K-under" (originally ), because it is the lower part of the original NATO K band, which was split into three bands (Ku, K, and Ka) because of the presence of the atmospheric water vapor resonance peak at 22.24 GHz, (1.35 cm) which made the center unusable for long range transmission. In radar applications, it ranges from 12 to 18 GHz according to the formal definition of radar frequency band nomenclature in IEEE Standard 521–2002. Ku band is primarily used for satellite communications, most notably the downlink used by direct broadcast satellites to broadcast satellite television, and for specific applications such as NASA's Tracking Data Relay Satellite used for International Space Station (ISS) communications and SpaceX Starlink satellites. Ku band satellites are also used for backhauls and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Astra 1A
Astra 1A was the first satellite launched and operated by SES (Société Européenne des Satellites), launched in December 1988. During its early days, it was often referred to as the Astra Satellite, as SES only operated one satellite originally. The satellite provided 16 transponders(+6 as rescue) and television coverage to Western Europe from 1989 to 2004. Astra 1A was retired and became derelict in December 2004. Channels Among the channels carried in the early years after launch were the entire four channel Sky Television (later British Sky Broadcasting, after the merger with rival British Satellite Broadcasting on the Marcopolo satellite), the services consisted of Sky Channel, Sky News, Sky Movies and Eurosport, the Scandinavian TV3 and TV1000, the German Pro7, Sat.1, RTL plus, 3sat and Teleclub, the Dutch RTL 4 as well as FilmNet, Screensport, MTV Europe, The Children's Channel and Lifestyle. Astra 1A began television broadcasts on 5 February 1989. U ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Luxembourg
Luxembourg, officially the Grand Duchy of Luxembourg, is a landlocked country in Western Europe. It is bordered by Belgium to the west and north, Germany to the east, and France on the south. Its capital and most populous city, Luxembourg City, is one of the four institutional seats of the European Union and hosts several EU institutions, notably the Court of Justice of the European Union, the highest judicial authority in the EU. As part of the Low Countries, Luxembourg has close historic, political, and cultural ties to Belgium and the Netherlands. Luxembourg's culture, people, and languages are greatly influenced by France and Germany: Luxembourgish, a Germanic language, is the only recognized national language of the Luxembourgish people and of the Grand Duchy of Luxembourg; French is the sole language for legislation; and both languages along with German are used for administrative matters. With an area of , Luxembourg is Europe's seventh-smallest count ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tuscaloosa, Alabama
Tuscaloosa ( ) is a city in and the county seat of Tuscaloosa County, Alabama, Tuscaloosa County in west-central Alabama, United States, on the Black Warrior River where the Gulf Coastal Plain, Gulf Coastal and Piedmont (United States), Piedmont plains meet. List of municipalities in Alabama, Alabama's fifth-most populous city, the population was 99,600 at the 2020 United States census, 2020 census, and was estimated to be 111,338 in 2023. It was known as Tuskaloosa until the early 20th century. It is also known as "the Druid City" because of the numerous Quercus nigra, water oaks planted in its downtown streets since the 1840s. Incorporated on December 13, 1819, it was named after Tuskaloosa, the chief of a band of Muskogean languages, Muskogean-speaking people defeated by the forces of Spanish explorer Hernando de Soto (explorer), Hernando de Soto in 1540 in the Mabila, Battle of Mabila, in what is now central Alabama. It served as Alabama's capital city from 1826 to 1846, w ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Low-noise Block Converter
A low-noise block downconverter (LNB) is the receiving device mounted on satellite dishes used for satellite TV reception, which collects the radio waves from the dish and converts them to a signal which is sent through a Coaxial cable, cable to the receiver inside the building. Also called a low-noise block, low-noise converter (LNC), or even low-noise downconverter (LND),Bains, Geoff. "Getting The Most Out Of An LNB" ''What Satellite & Digital TV'' (November, 2008) pp50-51 the device is sometimes inaccurately called a ''low-noise amplifier'' (''LNA''). The LNB is a combination of low-noise amplifier, frequency mixer, local oscillator and intermediate frequency (IF) amplifier. It serves as the RF front end of the satellite receiver, receiving the microwave transmission, microwave signal from the satellite collected by the dish, amplifying it, and Downconverter, downconverting the block of frequencies to a lower block of intermediate frequency, intermediate frequencies (IF). Th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Noise Figure
Noise figure (NF) and noise factor (''F'') are figures of merit that indicate degradation of the signal-to-noise ratio (SNR) that is caused by components in a signal chain. These figures of merit are used to evaluate the performance of an amplifier or a radio receiver, with lower values indicating better performance. The noise factor is defined as the ratio of the output noise power of a device to the portion thereof attributable to thermal noise in the input termination at standard noise temperature ''T''0 (usually 290 K). The noise factor is thus the ratio of actual output noise to that which would remain if the device itself did not introduce noise, which is equivalent to the ratio of input SNR to output SNR. The noise ''factor'' and noise ''figure'' are related, with the former being a unitless ratio and the latter being the logarithm of the noise factor, expressed in units of decibels (dB). General The noise figure is the difference in decibel (dB) between the noise ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Wire Mesh
Medical Subject Headings (MeSH) is a comprehensive controlled vocabulary for the purpose of indexing journal articles and books in the life sciences. It serves as a thesaurus of index terms that facilitates searching. Created and updated by the United States National Library of Medicine (NLM), it is used by the MEDLINE/PubMed article database and by NLM's catalog of book holdings. MeSH is also used by ClinicalTrials.gov registry to classify which diseases are studied by trials registered in ClinicalTrials. MeSH was introduced in the 1960s, with the NLM's own index catalogue and the subject headings of the Quarterly Cumulative Index Medicus (1940 edition) as precursors. The yearly printed version of MeSH was discontinued in 2007; MeSH is now available only online. It can be browsed and downloaded free of charge through PubMed. Originally in English, MeSH has been translated into numerous other languages and allows retrieval of documents from different origins. Structure MeSH v ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Baltimore, MD
Baltimore is the most populous city in the U.S. state of Maryland. With a population of 585,708 at the 2020 census and estimated at 568,271 in 2024, it is the 30th-most populous U.S. city. The Baltimore metropolitan area is the 20th-largest metropolitan area in the country at 2.84 million residents. The city is also part of the Washington–Baltimore combined statistical area, which had a population of 9.97 million in 2020. Baltimore was designated as an independent city by the Constitution of Maryland in 1851. Though not located under the jurisdiction of any county in the state, it forms part of the central Maryland region together with the surrounding county that shares its name. The land that is present-day Baltimore was used as hunting ground by Paleo-Indians. In the early 1600s, the Susquehannock began to hunt there. People from the Province of Maryland established the Port of Baltimore in 1706 to support the tobacco trade with Europe and established the Town of Ba ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
