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HRS Antenna
Curtain arrays are a class of large multielement directional radio transmitting wire antennas, used in the shortwave radio bands. They are a type of reflective array antenna, consisting of multiple wire dipole antennas, suspended in a vertical plane, often in front of a "curtain" reflector made of a flat vertical screen of many long parallel wires. These are suspended by support wires strung between pairs of tall steel towers, up to high. They are used for long-distance skywave (or ''skip'') transmission; they transmit a beam of radio waves at a shallow angle into the sky just above the horizon, which is reflected by the ionosphere back to Earth beyond the horizon. Curtain antennas are mostly used by international short wave radio stations to broadcast to large areas at transcontinental distances. Because of their powerful directional characteristics, curtain arrays are often used in government propaganda radio stations to beam propaganda broadcasts over national borde ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Biblis RFE RL 01
Biblis is a municipality in the Kreis Bergstraße, Bergstraße district in southern Hessen, Germany. Geography Location The municipality lies in the Rhine rift west of the Odenwald between Darmstadt to the north and Mannheim to the south; it also lies north of Bürstadt. Biblis lies directly north of the lower reaches of the Weschnitz, which empties into the Rhine only a few kilometres northwest of the municipality. Neighbouring municipalities Biblis borders in the north on the municipalities of Groß-Rohrheim and Gernsheim, in the east on the municipality of Einhausen, Hesse, Einhausen, in the south on the towns of Bürstadt and Lampertheim and in the west on the district-free city of Worms, Germany, Worms (Rhineland-Palatinate). Constituent communities Biblis's three ''Ortsteile'' are Biblis, Nordheim and Wattenheim. History In 836, Biblis had its first documentary mention in the Lorsch Abbey’s ''Lorsch Codex, Codex Laureshamensis'' under the name ''Bibifloz'' (“settleme ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Curtain Antenna At Hoerby Shortwave Station
A curtain is a piece of cloth or other material intended to block or obscure light, air drafts, or (in the case of a shower curtain), water. A curtain is also the movable screen or drape in a theatre that separates the stage from the auditorium or that serves as a backdrop/background. Curtains are often hung on the inside of a building's windows to block the passage of light. For instance, at night to aid sleeping, or to stop light from escaping outside the building (stopping people outside from being able to see inside, often for privacy reasons). In this application, they are also known as "draperies". Curtains hung over a doorway are known as portières. Curtains come in a variety of shapes, materials, sizes, colours, and patterns. They often have their own sections within department stores, while some shops are completely dedicated to selling curtains. Curtains vary according to cleanability, ultraviolet light deterioration, oil and dust retention, noise absorption, fire re ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Antenna Gain
In electromagnetics, an antenna's gain is a key performance parameter which combines the antenna's directivity and radiation efficiency. The term ''power gain'' has been deprecated by IEEE. In a transmitting antenna, the gain describes how well the antenna converts input power into radio waves headed in a specified direction. In a receiving antenna, the gain describes how well the antenna converts radio waves arriving from a specified direction into electrical power. When no direction is specified, gain is understood to refer to the peak value of the gain, the gain in the direction of the antenna's main lobe. A plot of the gain as a function of direction is called the antenna pattern or radiation pattern. It is not to be confused with directivity, which does ''not'' take an antenna's radiation efficiency into account. Gain or 'absolute gain' is defined as "The ratio of the radiation intensity in a given direction to the radiation intensity that would be produced if the p ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Main Lobe
In a radio antenna's radiation pattern, the main lobe, or main beam, is the lobe containing the higher power. This is the lobe that exhibits the greater field strength. The radiation pattern of most antennas shows a pattern of "''lobes''" at various angles, directions where the radiated signal strength reaches a maximum, separated by "''nulls''", angles at which the radiation falls to zero. In a directional antenna in which the objective is to emit the radio waves in one direction, the lobe in that direction is designed to have higher field strength than the others, so on a graph of the radiation pattern it appears biggest; this is the main lobe. The other lobes are called "''sidelobes''", and usually represent unwanted radiation in undesired directions. The sidelobe in the opposite direction from the main lobe is called the "''backlobe''". The radiation pattern referred to above is usually the horizontal radiation pattern, which is plotted as a function of azimuth about th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Horizontal Polarization
Polarization (also polarisation) is a property applying to transverse waves that specifies the geometrical orientation of the oscillations. In a transverse wave, the direction of the oscillation is perpendicular to the direction of motion of the wave. A simple example of a polarized transverse wave is vibrations traveling along a taut string ''(see image)''; for example, in a musical instrument like a guitar string. Depending on how the string is plucked, the vibrations can be in a vertical direction, horizontal direction, or at any angle perpendicular to the string. In contrast, in longitudinal waves, such as sound waves in a liquid or gas, the displacement of the particles in the oscillation is always in the direction of propagation, so these waves do not exhibit polarization. Transverse waves that exhibit polarization include electromagnetic waves such as light and radio waves, gravitational waves, and transverse sound waves (shear waves) in solids. An electromagnetic wa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Vertical Polarization
Polarization (also polarisation) is a property applying to transverse waves that specifies the geometrical orientation of the oscillations. In a transverse wave, the direction of the oscillation is perpendicular to the direction of motion of the wave. A simple example of a polarized transverse wave is vibrations traveling along a taut string ''(see image)''; for example, in a musical instrument like a guitar string. Depending on how the string is plucked, the vibrations can be in a vertical direction, horizontal direction, or at any angle perpendicular to the string. In contrast, in longitudinal waves, such as sound waves in a liquid or gas, the displacement of the particles in the oscillation is always in the direction of propagation, so these waves do not exhibit polarization. Transverse waves that exhibit polarization include electromagnetic waves such as light and radio waves, gravitational waves, and transverse sound waves (shear waves) in solids. An electromagnetic wave ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Wavelength
In physics, the wavelength is the spatial period of a periodic wave—the distance over which the wave's shape repeats. It is the distance between consecutive corresponding points of the same phase on the wave, such as two adjacent crests, troughs, or zero crossings, and is a characteristic of both traveling waves and standing waves, as well as other spatial wave patterns. The inverse of the wavelength is called the spatial frequency. Wavelength is commonly designated by the Greek letter ''lambda'' (λ). The term ''wavelength'' is also sometimes applied to modulated waves, and to the sinusoidal envelopes of modulated waves or waves formed by interference of several sinusoids. Assuming a sinusoidal wave moving at a fixed wave speed, wavelength is inversely proportional to frequency of the wave: waves with higher frequencies have shorter wavelengths, and lower frequencies have longer wavelengths. Wavelength depends on the medium (for example, vacuum, air, or water) that a wav ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dipole Antenna
In radio and telecommunications a dipole antenna or doublet is the simplest and most widely used class of antenna. The dipole is any one of a class of antennas producing a radiation pattern approximating that of an elementary electric dipole with a radiating structure supporting a line current so energized that the current has only one node at each end. A dipole antenna commonly consists of two identical conductive elements such as metal wires or rods. The driving current from the transmitter is applied, or for receiving antennas the output signal to the receiver is taken, between the two halves of the antenna. Each side of the feedline to the transmitter or receiver is connected to one of the conductors. This contrasts with a monopole antenna, which consists of a single rod or conductor with one side of the feedline connected to it, and the other side connected to some type of ground. A common example of a dipole is the "rabbit ears" television antenna found on broadcast telev ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Driven Element
{{Unreferenced, date=April 2016 In a multielement antenna array (such as a Yagi–Uda antenna), the driven element or active element is the element in the antenna (typically a metal rod) which is electrically connected to the receiver or transmitter. In a transmitting antenna it is ''driven'' or ''excited'' by the radio frequency current from the transmitter, and is the source of the radio waves. In a receiving antenna it collects the incoming radio waves for reception, and converts them to tiny oscillating electric currents, which are applied to the receiver. Multielement antennas like the Yagi typically consist of a driven element, connected to the receiver or transmitter through a feed line, and a number of other elements which are not driven, called parasitic elements. The driven element is often a dipole. The parasitic elements act as resonators and couple electromagnetically with the driven element, and serve to modify the radiation pattern of the antenna, directing the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Radio Liberty
Radio is the technology of signaling and communicating using radio waves. Radio waves are electromagnetic waves of frequency between 30 hertz (Hz) and 300 gigahertz (GHz). They are generated by an electronic device called a transmitter connected to an antenna which radiates the waves, and received by another antenna connected to a radio receiver. Radio is very widely used in modern technology, in radio communication, radar, radio navigation, remote control, remote sensing, and other applications. In radio communication, used in radio and television broadcasting, cell phones, two-way radios, wireless networking, and satellite communication, among numerous other uses, radio waves are used to carry information across space from a transmitter to a receiver, by modulating the radio signal (impressing an information signal on the radio wave by varying some aspect of the wave) in the transmitter. In radar, used to locate and track objects like aircraft, ships, spacecraft ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Radio Free Europe
Radio Free Europe/Radio Liberty (RFE/RL) is a United States government funded organization that broadcasts and reports news, information, and analysis to countries in Eastern Europe, Central Asia, Caucasus, and the Middle East where it says that "the free flow of information is either banned by government authorities or not fully developed". RFE/RL is a private, non-profit 501(c)(3) corporation supervised by the U.S. Agency for Global Media, an independent government agency overseeing all U.S. federal government international broadcasting services. Daisy Sindelar is the vice president and editor-in-chief of RFE. RFE/RL broadcasts in 27 languages to 23 countries. The organization has been headquartered in Prague, Czech Republic, since 1995, and has 21 local bureaus with over 500 core staff and 1,300 stringers and freelancers in countries throughout their broadcast region. In addition, it has 700 employees at its headquarters and corporate office in Washington, D.C. Radio Free Eur ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Voice Of America
Voice of America (VOA or VoA) is the state-owned news network and international radio broadcaster of the United States of America. It is the largest and oldest U.S.-funded international broadcaster. VOA produces digital, TV, and radio content in 48 languages which it distributes to affiliate stations around the globe. It is primarily viewed by a non-American audience. VOA was established in 1942, and the VOA charter (Public Laws 94-350 and 103–415) was signed into law in 1976 by President Gerald Ford. VOA is headquartered in Washington, D.C., and overseen by the U.S. Agency for Global Media (USAGM), an independent agency of the U.S. government. Funds are appropriated annually under the budget for embassies and consulates. In 2016, VOA broadcast an estimated 1,800 hours of radio and TV programming each week to approximately 236.6 million people worldwide with about 1,050 employees and a taxpayer-funded annual budget of . While Voice of America is seen by some foreign list ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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