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Whip Antenna
A whip antenna is an antenna consisting of a straight flexible wire or rod. The bottom end of the whip is connected to the radio receiver or transmitter. A whip antenna is a form of monopole antenna. The antenna is designed to be flexible so that it does not break easily, and the name is derived from the whip-like motion that it exhibits when disturbed. Whip antennas for portable radios are often made of a series of interlocking telescoping metal tubes, so they can be retracted when not in use. Longer whips, made for mounting on vehicles and structures, are made of a flexible fiberglass rod around a wire core and can be up to long. The length of a whip antenna is determined by the wavelength of the radio waves it is used with. Their length varies from compact electrically short antennas wavelength long, up to wavelength to improve directivity. The most common type is the ''quarter-wave whip'', which is approximately long. Whips are the most common type o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
DEGEN DE-1129 (2) Closeup
Degen may refer to: __NOTOC__ Weaponry *Swiss degen, a type of short sword of the late medieval and Renaissance period *the German term for a dress sword **Degen (SS), a type of straight saber used by the German SS **the German term for the épée in modern sport fencing Places *Degen, Switzerland, a former municipality in Surselva, Graubünden, Switzerland * Dêgên, a township in Nagqu prefecture, Tibet * Henry Degen House, Missouri, United States Other uses * Degen (surname) * Dejen Gebremeskel Dejen Gebremeskel (Amharic: ደጀን ገብረመስቀል; born 24 November 1989) is an Ethiopian long-distance runner who primarily competes in track events. His personal best of 12:46.81 minutes for the 5,000 metres ranks him as the ... (born 1989), Ethiopian long-distance runner * Slang for degenerate See also * * Degn (name) {{disambiguation, geo, given name ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Boom Box
A boombox is a transistorized portable music player featuring one or two cassette tape players/recorders and AM/FM radio, generally with a carrying handle. Beginning in the mid-1990s, a CD player was often included. Sound is delivered through an amplifier and two or more integrated loudspeakers. A boombox is a device typically capable of receiving radio stations and playing recorded music (usually cassette tapes or CDs usually at a high volume). Many models are also capable of recording onto cassette tapes from radio and other sources. In the 1990s, some boomboxes were available with MiniDisc recorders and players. Designed for portability, boomboxes can be powered by batteries as well as by line current. The boombox was introduced to the American market during the late 1970s. The desire for louder and heavier bass led to bigger and heavier boxes; by the 1980s, some boomboxes had reached the size of a suitcase. Some larger boomboxes even contained vertically mounted record ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Resonance
Resonance is a phenomenon that occurs when an object or system is subjected to an external force or vibration whose frequency matches a resonant frequency (or resonance frequency) of the system, defined as a frequency that generates a maximum amplitude response in the system. When this happens, the object or system absorbs energy from the external force and starts vibrating with a larger amplitude. Resonance can occur in various systems, such as mechanical, electrical, or acoustic systems, and it is often desirable in certain applications, such as musical instruments or radio receivers. However, resonance can also be detrimental, leading to excessive vibrations or even structural failure in some cases. All systems, including molecular systems and particles, tend to vibrate at a natural frequency depending upon their structure; when there is very little damping this frequency is approximately equal to, but slightly above, the resonant frequency. When an Oscillation, oscillat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Miramar Fire Department Firefighters Conduct Prescribed Burns 140612-M-RB277-066
Miramar is a place name of Spanish and Portuguese origin. It means "sea-view" or "sea sight" from ''mirar'' ("to look at, to watch") and ''mar'' ("sea"). It may refer to: Places Africa * Miramar, Port Elizabeth, see St Dominic's Priory School Asia *Miramar, Goa Europe *Miramar, Théoule-sur-Mer, France *Miramar, Portugal, a small seaside town in Vila Nova de Gaia municipality, subregion of Greater Porto Area *Miramar, Valencia, Spain * Miramar (Málaga), one of the Districts of Málaga, Spain North America *Miramar, Havana, an upscale district in the municipality of Playa, Cuba * Miramar, Baja California, Mexico, see USS Yorktown (PG-1) * Miramar, Tamaulipas, Mexico * Miramar, Bocas del Toro, Panama *Miramar, Colón, Colón Province, Panama * Miramar, Puerto Rico, a neighborhood of San Juan *Miramar, San Diego, California *Miramar, Florida, a city in Broward County * Miramar Beach, California *Miramar Beach, Florida, Walton County *Miramar District, Costa Rica *Naval Co ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Non-directional Antenna
In radio communication, an omnidirectional antenna is a class of antenna which radiates equal radio power in all directions perpendicular to an axis (azimuthal directions), with power varying with angle to the axis (elevation angle), declining to zero on the axis. When graphed in three dimensions ''(see graph)'' this radiation pattern is often described as ''doughnut-shaped''. This is different from an isotropic antenna, which radiates equal power in ''all'' directions, having a ''spherical'' radiation pattern. Omnidirectional antennas oriented vertically are widely used for nondirectional antennas on the surface of the Earth because they radiate equally in all horizontal directions, while the power radiated drops off with elevation angle so little radio energy is aimed into the sky or down toward the earth and wasted. Omnidirectional antennas are widely used for radio broadcasting antennas, and in mobile devices that use radio such as cell phones, FM radios, walkie-talkies, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Electric Field
An electric field (sometimes called E-field) is a field (physics), physical field that surrounds electrically charged particles such as electrons. In classical electromagnetism, the electric field of a single charge (or group of charges) describes their capacity to exert attractive or repulsive forces on another charged object. Charged particles exert attractive forces on each other when the sign of their charges are opposite, one being positive while the other is negative, and repel each other when the signs of the charges are the same. Because these forces are exerted mutually, two charges must be present for the forces to take place. These forces are described by Coulomb's law, which says that the greater the magnitude of the charges, the greater the force, and the greater the distance between them, the weaker the force. Informally, the greater the charge of an object, the stronger its electric field. Similarly, an electric field is stronger nearer charged objects and weaker f ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Vertical Polarization
, or , is a property of transverse waves which 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. One example of a polarized transverse wave is vibrations traveling along a taut string, 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 such as light consists of a coupled oscillating electr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Main Lobe
In a antenna (electronics), radio antennas, the main lobe or main beam is the region of the radiation pattern containing the highest Power (physics), power or exhibiting the greatest field strength. The radiation pattern of most antennas shows a pattern of "'':wikt:lobes, lobes''" at various directions, where the radiated signal strength reaches a local maximum, separated by "''null (radio), nulls''", 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, w ... [...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, Terms and D ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Omnidirectional Antenna
In radio communication, an omnidirectional antenna is a class of antenna (electronics), antenna which radiates equal radio power in all directions perpendicular to an Cartesian coordinate system, axis (azimuthal directions), with power varying with angle to the axis (elevation angle), declining to zero on the axis. When graphed in three dimensions ''(see graph)'' this radiation pattern is often described as ''doughnut-shaped''. This is different from an isotropic radiator, isotropic antenna, which radiates equal power in ''all'' directions, having a ''spherical'' radiation pattern. Omnidirectional antennas oriented vertically are widely used for nondirectional antennas on the surface of the Earth because they radiate equally in all horizontal directions, while the power radiated drops off with elevation angle so little radio energy is aimed into the sky or down toward the earth and wasted. Omnidirectional antennas are widely used for radio broadcasting antennas, and in mobile ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Amateur Radio
Amateur radio, also known as ham radio, is the use of the radio frequency radio spectrum, spectrum for purposes of non-commercial exchange of messages, wireless experimentation, self-training, private recreation, radiosport, contesting, and emergency, emergency communications. The term ''"radio amateur"'' is used to specify ''"a duly authorized person interested in radioelectric practice with a purely personal aim and without wikt:pecuniary, pecuniary interest"'' (either direct monetary or other similar reward); and to differentiate it from commercial broadcasting, public safety (police and fire), or two-way radio professional services (maritime, aviation, taxis, etc.). The amateur radio service (''amateur service'' and ''amateur-satellite service'') is established by the International Telecommunication Union (ITU) through their recommended radio regulations. National governments regulate technical and operational characteristics of transmissions and issue individual station li ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Base Station
Base station (or base radio station, BS) is – according to the International Telecommunication Union's (ITU) Radio Regulations (RR) – a " land station in the land mobile service." A base station is called '' node B'' in 3G, '' eNB'' in LTE ( 4G), and '' gNB'' in 5G. The term is used in the context of mobile telephony, wireless computer networking and other wireless communications and in land surveying. In surveying, it is a GPS receiver at a known position, while in wireless communications it is a transceiver connecting a number of other devices to one another and/or to a wider area. In mobile telephony, it provides the connection between mobile phones and the wider telephone network. In a computer network, it is a transceiver acting as a switch for computers in the network, possibly connecting them to a/another local area network and/or the Internet. In traditional wireless communications, it can refer to the hub of a dispatch fleet such as a taxi or delivery fl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
