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Blaw-Knox Tower
The Blaw-Knox company was an American manufacturer of steel structures and construction equipment based in Pittsburgh, Pennsylvania. The company is today best known for its radio towers, most of which were constructed during the 1930s in the United States. Although Blaw-Knox built many kinds of towers, the term Blaw-Knox tower (or radiator) usually refers to the company's unusual "diamond cantilever" design, which is stabilized by guy wires attached only at the vertical center of the mast, where its cross-section is widest. During the 1930s AM radio broadcasting stations adopted single mast radiator antennas, and the Blaw-Knox design was the first type used. A 1942 advertisement claims that 70% of all radio towers in the United States at the time were built by Blaw-Knox. The distinctive diamond-shaped towers became an icon of early radio. Several are listed on the United States National Register of Historic Places, [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
City
A city is a human settlement of notable size.Goodall, B. (1987) ''The Penguin Dictionary of Human Geography''. London: Penguin.Kuper, A. and Kuper, J., eds (1996) ''The Social Science Encyclopedia''. 2nd edition. London: Routledge. It can be defined as a permanent and densely settled place with administratively defined boundaries whose members work primarily on non-agricultural tasks. Cities generally have extensive systems for housing, transportation, sanitation, utilities, land use, production of goods, and communication. Their density facilitates interaction between people, government organisations and businesses, sometimes benefiting different parties in the process, such as improving efficiency of goods and service distribution. Historically, city-dwellers have been a small proportion of humanity overall, but following two centuries of unprecedented and rapid urbanization, more than half of the world population now lives in cities, which has had profound consequences for ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Voltage
Voltage, also known as electric pressure, electric tension, or (electric) potential difference, is the difference in electric potential between two points. In a static electric field, it corresponds to the work needed per unit of charge to move a test charge between the two points. In the International System of Units, the derived unit for voltage is named '' volt''. The voltage between points can be caused by the build-up of electric charge (e.g., a capacitor), and from an electromotive force (e.g., electromagnetic induction in generator, inductors, and transformers). On a macroscopic scale, a potential difference can be caused by electrochemical processes (e.g., cells and batteries), the pressure-induced piezoelectric effect, and the thermoelectric effect. A voltmeter can be used to measure the voltage between two points in a system. Often a common reference potential such as the ground of the system is used as one of the points. A voltage can represent either a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
California
California is a state in the Western United States, located along the Pacific Coast. With nearly 39.2million residents across a total area of approximately , it is the most populous U.S. state and the 3rd largest by area. It is also the most populated subnational entity in North America and the 34th most populous in the world. The Greater Los Angeles area and the San Francisco Bay Area are the nation's second and fifth most populous urban regions respectively, with the former having more than 18.7million residents and the latter having over 9.6million. Sacramento is the state's capital, while Los Angeles is the most populous city in the state and the second most populous city in the country. San Francisco is the second most densely populated major city in the country. Los Angeles County is the country's most populous, while San Bernardino County is the largest county by area in the country. California borders Oregon to the north, Nevada and Arizona to the east, t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Central Valley (California)
The Central Valley is a broad, elongated, flat valley that dominates the interior of California. It is wide and runs approximately from north-northwest to south-southeast, inland from and parallel to the Pacific coast of the state. It covers approximately , about 11% of California's land area. The valley is bounded by the Coast Ranges to the west and the Sierra Nevada to the east. The Central Valley is a region known for its agricultural productivity: it provides more than half of the fruits, vegetables, and nuts grown in the United States. More than of the valley are irrigated via reservoirs and canals. The valley hosts many cities, including the state capital Sacramento; as well as Redding, Chico, Stockton, Modesto, Merced, Fresno, Visalia, and Bakersfield. The Central Valley watershed comprises , or over a third of California. It consists of three main drainage systems: the Sacramento Valley in the north, which receives over of rain annually; the drier San Joa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hungary
Hungary ( hu, Magyarország ) is a landlocked country in Central Europe. Spanning of the Pannonian Basin, Carpathian Basin, it is bordered by Slovakia to the north, Ukraine to the northeast, Romania to the east and southeast, Serbia to the south, Croatia and Slovenia to the southwest, and Austria to the west. Hungary has a population of nearly 9 million, mostly ethnic Hungarians and a significant Romani people in Hungary, Romani minority. Hungarian language, Hungarian, the Languages of Hungary, official language, is the world's most widely spoken Uralic languages, Uralic language and among the few non-Indo-European languages widely spoken in Europe. Budapest is the country's capital and List of cities and towns of Hungary, largest city; other major urban areas include Debrecen, Szeged, Miskolc, Pécs, and Győr. The territory of present-day Hungary has for centuries been a crossroads for various peoples, including Celts, Ancient Rome, Romans, Germanic peoples, Germanic trib ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Szigetszentmiklós
Szigetszentmiklós () is a city in Pest County, Hungary, with around 40,000 inhabitants. Name * Sziget – island: Szigetszentmiklós is a town on Csepel Island * Szent Miklós – Saint Nicholas, who is the patron saint of Szigetszentmiklós Location Szigetszentmiklós is located south of Budapest in the Csepel Island on the Danube in Ráckeve Region. History After the Árpád dynasty was established, the region of today's Ráckeve belonged to the Hungarian king. Szigetszentmiklós became a town in January 1986. It mentioned in official document in 1264 the first time. Demographics Ethnicity * Hungarian: 91.3% * German: 0.6% * Slovak: 0.6% * Romani: 0.5% * Bulgarians: 0.2% * Ukrainian: 0.1% * Other/Undeclared: 8.5% Religious denomination * Roman Catholic: 35.9% * Greek Catholic: 2.2% * Calvinist: 21.4% * Lutheran: 1.0% * Other denomination: 2.1% * Non-religious: 20.7% * Undeclared: 16.6% Twin towns – sister cities Szigetszentmiklós is twinned with: * Hau ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lakihegy Tower
The Lakihegy Tower is a 314-metre-high (1,031 ft) radio mast at Szigetszentmiklós-Lakihegy in Hungary. The Blaw-Knox type tower was built in 1933 and was one of Europe's tallest structures at the time of construction. It was designed to provide broadcast coverage for Hungary with a 120 kW transmitter. It was built for the purpose of transmitting the radio station " Budapest I.", which it served until 1977. Developed in the U.S., the diamond-shaped mast was specially designed to radiate radio waves in such a way that reduce fading. Thus it was able to serve the whole country. The mast was destroyed by retreating German troops in World War II, but was later rebuilt in 1946. In 1968 the tower was upgraded to serve the new 300 kW transmitter (amongst others, the ceramic base insulator had to be replaced to withstand the higher voltages). In 1977 the new 2 MW transmitter at Solt has replaced the Lakihegy Tower as the primary national transmitter. Subsequently, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
AM Broadcasting
AM broadcasting is radio broadcasting using amplitude modulation (AM) transmissions. It was the first method developed for making audio radio transmissions, and is still used worldwide, primarily for medium wave (also known as "AM band") transmissions, but also on the longwave and shortwave radio bands. The earliest experimental AM transmissions began in the early 1900s. However, widespread AM broadcasting was not established until the 1920s, following the development of vacuum tube receivers and transmitters. AM radio remained the dominant method of broadcasting for the next 30 years, a period called the " Golden Age of Radio", until television broadcasting became widespread in the 1950s and received most of the programming previously carried by radio. Subsequently, AM radio's audiences have also greatly shrunk due to competition from FM (frequency modulation) radio, Digital Audio Broadcasting (DAB), satellite radio, HD (digital) radio, Internet radio, music streaming ser ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Surface Wave
In physics, a surface wave is a mechanical wave that propagates along the interface between differing media. A common example is gravity waves along the surface of liquids, such as ocean waves. Gravity waves can also occur within liquids, at the interface between two fluids with different densities. Elastic surface waves can travel along the surface of solids, such as '' Rayleigh'' or ''Love'' waves. Electromagnetic waves can also propagate as "surface waves" in that they can be guided along with a refractive index gradient or along an interface between two media having different dielectric constants. In radio transmission, a '' ground wave'' is a guided wave that propagates close to the surface of the Earth. Mechanical waves In seismology, several types of surface waves are encountered. Surface waves, in this mechanical sense, are commonly known as either '' Love waves'' (L waves) or '' Rayleigh waves''. A seismic wave is a wave that ''travels through the Earth, often ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Passive Radiator
In a radio antenna, a passive radiator or parasitic element is a conductive element, typically a metal rod, which is not electrically connected to anything else. Multielement antennas such as the Yagi–Uda antenna typically consist of a "'' driven element''" which is connected to the radio receiver or transmitter through a feed line, and parasitic elements, which are not. The purpose of the parasitic elements is to modify the radiation pattern of the radio waves emitted by the driven element, directing them in a beam in one direction, increasing the antenna's directivity (gain). A parasitic element does this by acting as a passive resonator, something like a guitar's sound box, absorbing the radio waves from the nearby driven element and re-radiating them again with a different phase. The waves from the different antenna elements interfere, strengthening the antenna's radiation in the desired direction, and cancelling out the waves in undesired directions. Descripti ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Radiation Pattern
In the field of antenna design the term radiation pattern (or antenna pattern or far-field pattern) refers to the ''directional'' (angular) dependence of the strength of the radio waves from the antenna or other source.Constantine A. Balanis: “Antenna Theory, Analysis and Design”, John Wiley & Sons, Inc., 2nd ed. 1982 David K Cheng: “Field and Wave Electromagnetics”, Addison-Wesley Publishing Company Inc., Edition 2, 1998. Edward C. Jordan & Keith G. Balmain; “Electromagnetic Waves and Radiating Systems” (2nd ed. 1968) Prentice-Hall. Particularly in the fields of fiber optics, lasers, and integrated optics, the term radiation pattern may also be used as a synonym for the near-field pattern or Fresnel pattern.Institute of Electrical and Electronics Engineers, “The IEEE standard dictionary of electrical and electronics terms”; 6th ed. New York, N.Y., Institute of Electrical and Electronics Engineers, c1997. IEEE Std 100-1996. d. Standards Coordinating Committee 10 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rhombohedron
In geometry, a rhombohedron (also called a rhombic hexahedron or, inaccurately, a rhomboid) is a three-dimensional figure with six faces which are rhombi. It is a special case of a parallelepiped where all edges are the same length. It can be used to define the rhombohedral lattice system, a honeycomb with rhombohedral cells. A cube is a special case of a rhombohedron with all sides square. In general a ''rhombohedron'' can have up to three types of rhombic faces in congruent opposite pairs, ''C''''i'' symmetry, order 2. Four points forming non-adjacent vertices of a rhombohedron necessarily form the four vertices of an orthocentric tetrahedron, and all orthocentric tetrahedra can be formed in this way. Rhombohedral lattice system The rhombohedral lattice system has rhombohedral cells, with 6 congruent rhombic faces forming a trigonal trapezohedron: : Special cases by symmetry * Cube: with Oh symmetry, order 48. All faces are squares. * Trigonal trapezohedron (also c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
