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Short-wave
Shortwave radio is radio transmission using shortwave (SW) radio frequencies. There is no official definition of the band, but the range always includes all of the high frequency band (HF), which extends from 3 to 30 MHz (100 to 10 metres); above the medium frequency band (MF), to the bottom of the VHF band. Radio waves in the shortwave band can be reflected or refracted from a layer of electrically charged atoms in the atmosphere called the ionosphere. Therefore, short waves directed at an angle into the sky can be reflected back to Earth at great distances, beyond the horizon. This is called skywave or "skip" propagation. Thus shortwave radio can be used for communication over very long distances, in contrast to radio waves of higher frequency, which travel in straight lines (line-of-sight propagation) and are limited by the visual horizon, about 64 km (40 miles). Shortwave broadcasts of radio programs played an important role in the early days of radi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Long Wave
In radio, longwave, long wave or long-wave, and commonly abbreviated LW, refers to parts of the radio spectrum with wavelengths longer than what was originally called the medium-wave broadcasting band. The term is historic, dating from the early 20th century, when the radio spectrum was considered to consist of longwave (LW), medium-wave (MW), and short-wave (SW) radio bands. Most modern radio systems and devices use wavelengths which would then have been considered 'ultra-short'. In contemporary usage, the term ''longwave'' is not defined precisely, and its intended meaning varies. It may be used for radio wavelengths longer than 1,000 m i.e. frequencies up to 300 kilohertz (kHz), including the International Telecommunication Union's (ITU's) low frequency (LF, 30–300 kHz) and very low frequency (VLF, 3–30 kHz) bands. Sometimes the upper limit is taken to be higher than 300 kHz, but not above the start of the medium wave broadcast band at 520& ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ionosphere
The ionosphere () is the ionized part of the upper atmosphere of Earth, from about to above sea level, a region that includes the thermosphere and parts of the mesosphere and exosphere. The ionosphere is ionized by solar radiation. It plays an important role in atmospheric electricity and forms the inner edge of the magnetosphere. It has practical importance because, among other functions, it influences radio propagation to distant places on Earth. History of discovery As early as 1839, the German mathematician and physicist Carl Friedrich Gauss postulated that an electrically conducting region of the atmosphere could account for observed variations of Earth's magnetic field. Sixty years later, Guglielmo Marconi received the first trans-Atlantic radio signal on December 12, 1901, in St. John's, Newfoundland (now in Canada) using a kite-supported antenna for reception. The transmitting station in Poldhu, Cornwall, used a spark-gap transmitter to produce a signal with a f ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
History Of Radio
The early history of radio is the history of technology that produces and uses radio instruments that use radio waves. Within the timeline of radio, many people contributed theory and inventions in what became radio. Radio development began as " wireless telegraphy". Later radio history increasingly involves matters of broadcasting. Discovery In an 1864 presentation, published in 1865, James Clerk Maxwell proposed theories of electromagnetism, with mathematical proofs, that showed that light and predicted that radio and x-rays were all types of electromagnetic waves propagating through free space. Between 1886 and 1888 Heinrich Rudolf Hertz published the results of experiments wherein he was able to transmit electromagnetic waves (radio waves) through the air, proving Maxwell's electromagnetic theory. [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Grundig Satellit Professional 400
Grundig (; ) is a German consumer electronics manufacturer owned by the Turkish Arçelik A.Ş., the white goods (major appliance) manufacturer of Turkish conglomerate Koç Holding. The company made domestic appliances and personal-care products. Originally a German consumer electronic company, Grundig GmbH was founded in 1945 by Max Grundig and eventually headquartered in Nuremberg. It grew to become one of the leading radio, TV, recorder and other electronics goods manufacturers of Europe in the following decades of the 20th century. In the 1970s, Philips began acquiring Grundig AG's shares, leading to complete control in 1993. In 1998, Philips divested Grundig. In 2007, Koç Holding bought Grundig and put the brand under its home-appliances subsidiary Arcelik A.Ş. Koç is a publicly listed conglomerate with more than 80,000 employees. History Grundig began in 1945 with the establishment of a store named Fürth, Grundig & Wurzer (RVF), which sold radios and was headq ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Guglielmo Marconi 1901 Wireless Signal
Guglielmo () is the Italian form of the masculine name William. It may refer to: People with the given name Guglielmo: * Guglielmo I Gonzaga (1538–1587), Duke of Mantua and Montferrat * Guglielmo Achille Cavellini (1914–1990), influential Italian art collector and mail artist * Guglielmo Agnelli (c. 1238 – 1313), Italian sculptor and architect * Guglielmo Bergamesco (16th century), Italian architect * Guglielmo Borremans (born 1672), Baroque painter * Guglielmo Caccia (1568–1625), Italian painter * Guglielmo da Leoni (c. 1664 – 1740), Italian painter and engraver * Guglielmo da Marsiglia (1475–1537), Italian painter of stained glass * Guglielmo della Porta (c. 1500 – 1577), Italian architect and sculptor * Guglielmo della Scala (died 1404), Lord of Verona * Guglielmo Ebreo da Pesaro (15th century), Italian dancing-master * Guglielmo Embriaco (born c. 1040), Genoese merchant and military leader * Guglielmo Ferrero (1871–1942), Italian historian, journalist an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cape Verde
, national_anthem = () , official_languages = Portuguese , national_languages = Cape Verdean Creole , capital = Praia , coordinates = , largest_city = capital , demonym = Cape Verdean or Cabo Verdean , ethnic_groups_year = 2017 , government_type = Unitary semi-presidential republic , leader_title1 = President , leader_name1 = José Maria Neves , leader_title2 = Prime Minister , leader_name2 = Ulisses Correia e Silva , legislature = National Assembly , area_rank = 166th , area_km2 = 4033 , area_sq_mi = 1,557 , percent_water = negligible , population_census = 561,901 , population_census_rank = 172nd , population_census_year = 2021 , population_density_km2 = 123.7 , population_density_sq_mi = 325.0 , population_density_rank = 89th , GDP_PPP ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cornwall
Cornwall (; kw, Kernow ) is a historic county and ceremonial county in South West England. It is recognised as one of the Celtic nations, and is the homeland of the Cornish people. Cornwall is bordered to the north and west by the Atlantic Ocean, to the south by the English Channel, and to the east by the county of Devon, with the River Tamar forming the border between them. Cornwall forms the westernmost part of the South West Peninsula of the island of Great Britain. The southwesternmost point is Land's End and the southernmost Lizard Point. Cornwall has a population of and an area of . The county has been administered since 2009 by the unitary authority, Cornwall Council. The ceremonial county of Cornwall also includes the Isles of Scilly, which are administered separately. The administrative centre of Cornwall is Truro, its only city. Cornwall was formerly a Brythonic kingdom and subsequently a royal duchy. It is the cultural and ethnic origin of the Cor ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Poldhu
Poldhu is a small area in south Cornwall, England, UK, situated on the Lizard Peninsula; it comprises Poldhu Point and Poldhu Cove. Poldhu means "black pool" in Cornish. Poldhu lies on the coast of Mount's Bay and is in the northern part of the parish of Mullion; the churchtown is to the south-east. On the north side of Poldhu Cove is the parish of Gunwalloe and the village of Porthleven is a further to the north. Poldhu Point became the site of one of the main technological advances of the early twentieth century when, on 12 December 1901, a wireless signal was sent by Thomas Barron in Poldhu to St John's, Newfoundland, and received by Marconi. The technology was a precursor to radio, television, satellites and the internet, with the earth station at Goonhilly Downs a nearby example. The beach at Poldhu was heavily mined during World War II to prevent any prospect of a German force landing there. As an unfortunate result, on 24 April 1943, Royal Air Force Volunteer R ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Charles Samuel Franklin
Charles Samuel Franklin (1879 – 10 December 1964), who published as C. S. Franklin, was a noted British radio pioneer. Biography Franklin was born in London, the youngest of a family of 13, and educated at Finsbury Technical College in Finsbury, England, under Silvanus P. Thompson. After graduation in 1899 he joined the Marconi Company where he spent his entire professional career. He was first sent to South Africa to provide equipment for the Boer War, then spent 2 years in Russia. After his return to the UK, he invented a number of important radio devices including the variable capacitor (patented 1902), ganged tuning (1907), variable coupling (1907), coaxial cable, and the Franklin oscillator. Today Franklin is best known for the Franklin beam aerial, his shortwave antenna. From the Marconi company's Poldhu station in 1923 and 1924, he sent shortwave transmissions to Guglielmo Marconi on his yacht Electra in the South Atlantic. Franklin was also active in early televi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Guglielmo Marconi
Guglielmo Giovanni Maria Marconi, 1st Marquis of Marconi (; 25 April 187420 July 1937) was an Italian inventor and electrical engineer, known for his creation of a practical radio wave-based wireless telegraph system. This led to Marconi being credited as the inventor of radio, and he shared the 1909 Nobel Prize in Physics with Karl Ferdinand Braun "in recognition of their contributions to the development of wireless telegraphy".Guglielmo Marconi: The Nobel Prize in Physics 1909 . nobelprize.org Marconi was also an entrepreneur, businessman, and founder of The Wireless Telegraph & Signal Company in the |
Transmitter
In electronics and telecommunications, a radio transmitter or just transmitter is an electronic device which produces radio waves with an antenna. The transmitter itself generates a radio frequency alternating current, which is applied to the antenna. When excited by this alternating current, the antenna radiates radio waves. Transmitters are necessary component parts of all electronic devices that communicate by radio, such as radio and television broadcasting stations, cell phones, walkie-talkies, wireless computer networks, Bluetooth enabled devices, garage door openers, two-way radios in aircraft, ships, spacecraft, radar sets and navigational beacons. The term ''transmitter'' is usually limited to equipment that generates radio waves for communication purposes; or radiolocation, such as radar and navigational transmitters. Generators of radio waves for heating or industrial purposes, such as microwave ovens or diathermy equipment, are not usually called transmi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Kilohertz
The hertz (symbol: Hz) is the unit of frequency in the International System of Units (SI), equivalent to one event (or cycle) per second. The hertz is an SI derived unit whose expression in terms of SI base units is s−1, meaning that one hertz is the reciprocal of one second. It is named after Heinrich Rudolf Hertz (1857–1894), the first person to provide conclusive proof of the existence of electromagnetic waves. Hertz are commonly expressed in multiples: kilohertz (kHz), megahertz (MHz), gigahertz (GHz), terahertz (THz). Some of the unit's most common uses are in the description of periodic waveforms and musical tones, particularly those used in radio- and audio-related applications. It is also used to describe the clock speeds at which computers and other electronics are driven. The units are sometimes also used as a representation of the energy of a photon, via the Planck relation ''E'' = ''hν'', where ''E'' is the photon's energy, ''ν'' is its frequ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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