213 relations: Absorption (electromagnetic radiation), AM broadcasting, Amateur radio, Amplifier, Angle of incidence (optics), Annalen der Physik, Antenna aperture, Antenna array, Antenna boresight, Antenna efficiency, Antenna feed, Antenna gain, Antenna measurement, Antenna tuner, Balanced line, Balun, Bandwidth (signal processing), Base station, Batwing antenna, Beverage antenna, Bologna, Boombox, Box kite, Capacitor, Cell site, Cellular repeater, Characteristic impedance, Circular polarization, Circulator, Coaxial cable, Collinear antenna array, Communications receiver, Communications satellite, Complex conjugate, Complex number, Copper loss, Cordless telephone, Corner reflector antenna, Counterpoise (ground system), Curtain array, Decibel, Dielectric, Dielectric resonator antenna, Digital terrestrial television, Dipole antenna, Direction finding, Directional antenna, Directivity, Driven element, DXing, ..., E-plane and H-plane, Electric field, Electric power, Electrical conductor, Electrical efficiency, Electrical impedance, Electrical length, Electrical reactance, Electrical resistivity and conductivity, Electrically small antenna, Electromagnetic coil, Electromagnetic radiation, Electromagnetism, Electronic countermeasure, Ellipse, Error detection and correction, Extremely high frequency, Feed line, Ferrite (magnet), Ferrite core, Field strength, Frequency mixer, Fresnel equations, Friis transmission equation, Gain (electronics), Ghosting (television), Global Positioning System, Ground (electricity), Ground plane, Guglielmo Marconi, Heinrich Hertz, Helical antenna, Helix, High frequency, Horn antenna, Image antenna, Impedance matching, In-phase and quadrature components, Inductance, Inductor, Insulator (electricity), Intensity (physics), Inverse-square law, Inverted-F antenna, Ionosphere, Isolator (microwave), Isotropic radiator, James Clerk Maxwell, Land mobile radio system, LC circuit, Leaky wave antenna, Lens (optics), Line-of-sight propagation, Linear function, Linear polarization, Loading coil, Log-periodic antenna, Logarithm, Loop antenna, Low frequency, Magnetic field, Main lobe, Marine radar, Mast radiator, Mathematical model, Medium frequency, Medium wave, Microstrip, Microstrip antenna, Microwave, Microwave radiometer, Mobile broadband modem, Mobile phone, Monopole antenna, Multipath propagation, Near and far field, Null (radio), Numerical Electromagnetics Code, Omnidirectional antenna, Parabolic antenna, Parabolic reflector, Passive radiator, Patch antenna, Permittivity, Phase (waves), Phase shift module, Phased array, Polarization (waves), Printed circuit board, Q factor, Quad antenna, Radar, Radar gun, Radial (radio), Radiation pattern, Radiation resistance, Radio, Radio astronomy, Radio broadcasting, Radio frequency, Radio masts and towers, Radio receiver, Radio station, Radio telescope, Radio wave, Random wire antenna, Reciprocity (electromagnetism), Reflective array antenna, Reflector (antenna), Refractive index, Relative permittivity, Remote control, Resonance, Resonator, RF connector, Rhombic antenna, Rhombus, Right-hand rule, Root mean square, Rubber ducky antenna, Satellite television, Sector antenna, Selectivity (electronic), Shortwave broadband antenna, Shortwave radio, Side lobe, Signal-to-noise ratio, Skywave, Slot antenna, Smart antenna, Specular reflection, Speed of light, Sphere, Standing wave, Standing wave ratio, Surface wave, T-antenna, Television, Television antenna, Terrestrial television, Terrestrial Trunked Radio, Thévenin's theorem, Torus, Transformer, Transmission (telecommunications), Transmission line, Transmitter, Transverse wave, Traveling-wave antenna, Turnstile antenna, Two-way radio, Umbrella antenna, Vehicle audio, Very low frequency, Wave interference, Waveguide, Waveguide (electromagnetism), Wavelength, Whip antenna, Wi-Fi, Wind engineering, Wireless LAN, Yagi–Uda antenna. Expand index (163 more) » « Shrink index
In physics, absorption of electromagnetic radiation is the way in which the energy of a photon is taken up by matter, typically the electrons of an atom.
AM broadcasting is a radio broadcasting technology, which employs amplitude modulation (AM) transmissions.
Amateur radio, also known as ham radio, describes the use of radio frequency spectrum for purposes of non-commercial exchange of messages, wireless experimentation, self-training, private recreation, radiosport, contesting, and emergency communication.
An amplifier, electronic amplifier or (informally) amp is an electronic device that can increase the power of a signal (a time-varying voltage or current).
In geometric optics, the angle of incidence is the angle between a ray incident on a surface and the line perpendicular to the surface at the point of incidence, called the normal.
Annalen der Physik (English: Annals of Physics) is one of the oldest scientific journals on physics and has been published since 1799.
In electromagnetics and antenna theory, antenna aperture, effective area, or receiving cross section, is a measure of how effective an antenna is at receiving the power of electromagnetic radiation (such as radio waves).
An antenna array (or array antenna) is a set of multiple connected antennas which work together as a single antenna, to transmit or receive radio waves.
In telecommunications and radar engineering, antenna boresight is the axis of maximum gain (maximum radiated power) of a directional antenna.
In antenna theory, antenna efficiency is most often used to mean radiation efficiency.
In telecommunications and electronics, an antenna feed refers to the components of an antenna which feed the radio waves to the rest of the antenna structure, or in receiving antennas collect the incoming radio waves, convert them to electric currents and transmit them to the receiver.
In electromagnetics, an antenna's power gain or simply gain is a key performance number which combines the antenna's directivity and electrical efficiency.
Antenna measurement techniques refers to the testing of antennas to ensure that the antenna meets specifications or simply to characterize it.
An antenna tuner, a matchbox, transmatch, antenna tuning unit (ATU), antenna coupler, or feedline coupler is a device connected between a radio transmitter or receiver and its antenna to improve power transfer between them by matching the impedance of the radio to the antenna's feedline.
In telecommunications and professional audio, a balanced line or balanced signal pair is a transmission line consisting of two conductors of the same type, each of which have equal impedances along their lengths and equal impedances to ground and to other circuits.
A balun (for balanced to unbalanced) is an electrical device that converts between a balanced signal (two signals working against each other where ground is irrelevant) and an unbalanced signal (a single signal working against ground or pseudo-ground).
Bandwidth is the difference between the upper and lower frequencies in a continuous band of frequencies.
Base station (or base radio station) is – according to the International Telecommunication Union's (ITU) Radio Regulations (RR) – a "land station in the land mobile service." The term is used in the context of mobile telephony, wireless computer networking and other wireless communications and in land surveying.
A batwing or super turnstile antenna is a type of broadcasting antenna used at VHF and UHF frequencies, named for its distinctive shape which resembles a bat wing or bow tie.
The Beverage antenna or "wave antenna" is a long-wire receiving antenna mainly used in the low frequency and medium frequency radio bands, invented by Harold H. Beverage in 1921.
Bologna (Bulåggna; Bononia) is the capital and largest city of the Emilia-Romagna Region in Northern Italy.
A boombox is a transistorized portable music player featuring one or two cassette tape recorder/players and AM/FM radio, generally with a carrying handle.
A box kite is a high performance kite, noted for developing relatively high lift; it is a type within the family of cellular kites.
A capacitor is a passive two-terminal electrical component that stores potential energy in an electric field.
A cell site or cell tower is a cellular-enabled mobile device site where antennae and electronic communications equipment are placed — typically on a radio mast, tower, or other raised structure — to create a cell (or adjacent cells) in a cellular network.
A cellular repeater (also known as cell phone signal booster or amplifier) is a type of bi-directional amplifier used to improve cell phone reception.
The characteristic impedance or surge impedance (usually written Z0) of a uniform transmission line is the ratio of the amplitudes of voltage and current of a single wave propagating along the line; that is, a wave travelling in one direction in the absence of reflections in the other direction.
In electrodynamics, circular polarization of an electromagnetic wave is a polarization state in which, at each point, the electric field of the wave has a constant magnitude but its direction rotates with time at a steady rate in a plane perpendicular to the direction of the wave.
A circulator is a passive non-reciprocal three- or four-port device, in which a microwave or radio frequency signal entering any port is transmitted to the next port in rotation (only).
Cross-sectional view of a coaxial cable Coaxial cable, or coax (pronounced), is a type of electrical cable that has an inner conductor surrounded by a tubular insulating layer, surrounded by a tubular conducting shield.
In telecommunications, a collinear antenna array is an array of dipole antennas mounted in such a manner that the corresponding elements of each antenna are parallel and collinear, that is they are located along a common line or axis.
A communications receiver is a type of radio receiver used as a component of a radio communication link.
A communications satellite is an artificial satellite that relays and amplifies radio telecommunications signals via a transponder; it creates a communication channel between a source transmitter and a receiver at different locations on Earth.
In mathematics, the complex conjugate of a complex number is the number with an equal real part and an imaginary part equal in magnitude but opposite in sign.
A complex number is a number that can be expressed in the form, where and are real numbers, and is a solution of the equation.
Copper loss is the term often given to heat produced by electrical currents in the conductors of transformer windings, or other electrical devices.
A cordless telephone or portable telephone is a telephone in which the handset is portable and communicates with the body of the phone by radio, instead of being attached by a cord.
A corner reflector antenna is a type of directional antenna used at VHF and UHF frequencies.
In electronics and radio communication a counterpoise is a network of suspended horizontal wires or cables (or a metal screen), used as a substitute for an earth (ground) connection in a radio antenna system.
Curtain arrays are a class of large multielement directional wire radio transmitting antennas, used in the shortwave radio bands.
The decibel (symbol: dB) is a unit of measurement used to express the ratio of one value of a physical property to another on a logarithmic scale.
A dielectric (or dielectric material) is an electrical insulator that can be polarized by an applied electric field.
A dielectric resonator antenna (DRA) is a radio antenna mostly used at microwave frequencies and higher, that consists of a block of ceramic material of various shapes, the dielectric resonator, mounted on a metal surface, a ground plane.
Digital terrestrial television (DTTV or DTT) is a technology for broadcast television in which land-based (terrestrial) television stations broadcast television content by radio waves to televisions in consumers' residences in a digital format.
In radio and telecommunications a dipole antenna or doublet is the simplest and most widely used class of antenna.
Direction finding (DF), or radio direction finding (RDF), is the measurement of the direction from which a received signal was transmitted.
A directional antenna or beam antenna is an antenna which radiates or receives greater power in specific directions allowing increased performance and reduced interference from unwanted sources.
In electromagnetics, directivity is a parameter of an antenna or optical system which measures the degree to which the radiation emitted is concentrated in a single direction.
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 RF 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 radio waves in one direction, increasing the gain of the antenna. An antenna may have more than one driven element, although the most common multielement antenna, the Yagi, usually has only one. For example, transmitting antennas for AM radio stations often consist of several mast radiators, each of which functions as a half-wave monopole driven element, to create a particular radiation pattern. A two-element array with the elements spaced a quarter wavelength apart has a distinct cardioid radiation pattern when the second element is driven with a source -90° out of phase relative to the first element. A log-periodic antenna (LPDA) consists of many dipole elements of decreasing length, all of which are driven. However because they are different lengths, only one of the many dipoles is resonant at a given frequency, so only one is driven at a time. The dipole that is driven depends on the frequency of the signal. Phased arrays may have hundreds of driven elements. Household multiband television antennas generally consist of a hybrid between a UHF Yagi with one driven dipole and a log-periodic for VHF behind that with alternating active elements. The driven elements between the UHF and VHF are then coupled and often matched for a 75 ohm coaxial downlead to the receiver. When a "driven element" is referred to in an antenna array, it is often assumed that other elements are not driven (i.e. parasitic, passive) and that the array is tightly coupled (spacing far below a wavelength). Category:Antennas (radio).
DXing is the hobby of receiving and identifying distant radio or television signals, or making two way radio contact with distant stations in amateur radio, citizens' band radio or other two way radio communications.
The E-plane and H-plane are reference planes for linearly polarized waveguides, antennas and other microwave devices.
An electric field is a vector field surrounding an electric charge that exerts force on other charges, attracting or repelling them.
Electric power is the rate, per unit time, at which electrical energy is transferred by an electric circuit.
In physics and electrical engineering, a conductor is an object or type of material that allows the flow of an electrical current in one or more directions.
The efficiency of an entity (a device, component, or system) in electronics and electrical engineering is defined as useful power output divided by the total electrical power consumed (a fractional expression), typically denoted by the Greek small letter eta (η – ήτα).
Electrical impedance is the measure of the opposition that a circuit presents to a current when a voltage is applied.
In telecommunications and electrical engineering, electrical length (or phase length) refers to the length of an electrical conductor in terms of the phase shift introduced by transmission over that conductor at some frequency.
In electrical and electronic systems, reactance is the opposition of a circuit element to a change in current or voltage, due to that element's inductance or capacitance.
Electrical resistivity (also known as resistivity, specific electrical resistance, or volume resistivity) is a fundamental property that quantifies how strongly a given material opposes the flow of electric current.
An electrically short antenna is an antenna of length 2h, such that 2 \pi h\over\lambda \scriptstyle\ll 1, where λ is the free space wavelength.
An electromagnetic coil is an electrical conductor such as a wire in the shape of a coil, spiral or helix.
In physics, electromagnetic radiation (EM radiation or EMR) refers to the waves (or their quanta, photons) of the electromagnetic field, propagating (radiating) through space-time, carrying electromagnetic radiant energy.
Electromagnetism is a branch of physics involving the study of the electromagnetic force, a type of physical interaction that occurs between electrically charged particles.
An electronic countermeasure (ECM) is an electrical or electronic device designed to trick or deceive radar, sonar or other detection systems, like infrared (IR) or lasers.
In mathematics, an ellipse is a curve in a plane surrounding two focal points such that the sum of the distances to the two focal points is constant for every point on the curve.
In information theory and coding theory with applications in computer science and telecommunication, error detection and correction or error control are techniques that enable reliable delivery of digital data over unreliable communication channels.
Extremely high frequency (EHF) is the International Telecommunication Union (ITU) designation for the band of radio frequencies in the electromagnetic spectrum from 30 to 300 gigahertz (GHz).
In a radio antenna, the feed line (feedline), or feeder, is the cable or other transmission line that connects the antenna with the radio transmitter or receiver.
A ferrite is a ceramic material made by mixing and firing large proportions iron(III) oxide (Fe2O3, rust) blended with small proportions of one or more additional metallic elements, such as barium, manganese, nickel, and zinc.
In electronics, a ferrite core is a type of magnetic core made of ferrite on which the windings of electric transformers and other wound components such as inductors are formed.
In physics, field strength means the magnitude of a vector-valued field (e.g., in volts per meter, V/m, for an electric field E).
In electronics, a mixer, or frequency mixer, is a nonlinear electrical circuit that creates new frequencies from two signals applied to it.
The Fresnel equations (or Fresnel coefficients) describe the reflection and transmission of light (or electromagnetic radiation in general) when incident on an interface between different optical media.
The Friis transmission formula is used in telecommunications engineering, equating the power at the terminals of a receive antenna as the product of power density of the incident wave and the effective aperture of the receiving antenna under idealized conditions given another antenna some distance away transmitting a known amount of power.
In electronics, gain is a measure of the ability of a two-port circuit (often an amplifier) to increase the power or amplitude of a signal from the input to the output port by adding energy converted from some power supply to the signal.
In television, a ghost is a replica of the transmitted image, offset in position, that is super-imposed on top of the main image.
The Global Positioning System (GPS), originally Navstar GPS, is a satellite-based radionavigation system owned by the United States government and operated by the United States Air Force.
In electrical engineering, ground or earth is the reference point in an electrical circuit from which voltages are measured, a common return path for electric current, or a direct physical connection to the earth.
In electrical engineering, a ground plane is an electrically conductive surface, usually connected to electrical ground.
Guglielmo Marconi, 1st Marquis of Marconi (25 April 187420 July 1937) was an Italian inventor and electrical engineer known for his pioneering work on long-distance radio transmission and for his development of Marconi's law and a radio telegraph system.
Heinrich Rudolf Hertz (22 February 1857 – 1 January 1894) was a German physicist who first conclusively proved the existence of the electromagnetic waves theorized by James Clerk Maxwell's electromagnetic theory of light.
A helical antenna is an antenna consisting of one or more conducting wires (monofilar, bifilar, or quadrifilar with 1, 2, or 4 wires respectively) wound in the form of a helix.
A helix, plural helixes or helices, is a type of smooth space curve, i.e. a curve in three-dimensional space.
High frequency (HF) is the ITU designation for the range of radio frequency electromagnetic waves (radio waves) between 3 and 30 megahertz (MHz).
A horn antenna or microwave horn is an antenna that consists of a flaring metal waveguide shaped like a horn to direct radio waves in a beam.
In telecommunications and antenna design, an image antenna is an electrical mirror-image of an antenna element formed by the radio waves reflecting from a conductive surface called a ground plane, such as the surface of the earth.
In electronics, impedance matching is the practice of designing the input impedance of an electrical load or the output impedance of its corresponding signal source to maximize the power transfer or minimize signal reflection from the load.
In electrical engineering, a sinusoid with angle modulation can be decomposed into, or synthesized from, two amplitude-modulated sinusoids that are offset in phase by one-quarter cycle (/2 radians).
In electromagnetism and electronics, inductance is the property of an electrical conductor by which a change in electric current through it induces an electromotive force (voltage) in the conductor.
An inductor, also called a coil, choke or reactor, is a passive two-terminal electrical component that stores energy in a magnetic field when electric current flows through it.
An electrical insulator is a material whose internal electric charges do not flow freely; very little electric current will flow through it under the influence of an electric field.
In physics, intensity is the power transferred per unit area, where the area is measured on the plane perpendicular to the direction of propagation of the energy.
The inverse-square law, in physics, is any physical law stating that a specified physical quantity or intensity is inversely proportional to the square of the distance from the source of that physical quantity.
An inverted-F antenna is a type of antenna used in wireless communication.
The ionosphere is the ionized part of Earth's upper atmosphere, from about to altitude, a region that includes the thermosphere and parts of the mesosphere and exosphere.
An isolator is a two-port device that transmits microwave or radio frequency power in one direction only.
An isotropic radiator is a theoretical point source of electromagnetic or sound waves which radiates the same intensity of radiation in all directions.
James Clerk Maxwell (13 June 1831 – 5 November 1879) was a Scottish scientist in the field of mathematical physics.
Land mobile radio system (LMRS), also called public land mobile radio or private land mobile radio, is a wireless communications system intended for use by terrestrial users in vehicles (mobiles) or on foot (portables).
An LC circuit, also called a resonant circuit, tank circuit, or tuned circuit, is an electric circuit consisting of an inductor, represented by the letter L, and a capacitor, represented by the letter C, connected together.
Leaky-Wave Antenna (LWA) belong to the more general class of Traveling wave antenna, that use a traveling wave on a guiding structure as the main radiating mechanism.
A lens is a transmissive optical device that focuses or disperses a light beam by means of refraction.
Line-of-sight propagation is a characteristic of electromagnetic radiation or acoustic wave propagation which means waves travel in a direct path from the source to the receiver.
In mathematics, the term linear function refers to two distinct but related notions.
In electrodynamics, linear polarization or plane polarization of electromagnetic radiation is a confinement of the electric field vector or magnetic field vector to a given plane along the direction of propagation.
A loading coil or load coil is an inductor that is inserted into an electronic circuit to increase its inductance.
A log-periodic antenna (LP), also known as a log-periodic array or log-periodic aerial, is a multi-element, directional antenna designed to operate over a wide band of frequencies.
In mathematics, the logarithm is the inverse function to exponentiation.
A loop antenna is a radio antenna consisting of a loop or coil of wire, tubing, or other electrical conductor usually fed by a balanced source or feeding a balanced load.
Low frequency (low freq) or LF is the ITU designation for radio frequencies (RF) in the range of 30 kilohertz (kHz)–300 kHz.
A magnetic field is a vector field that describes the magnetic influence of electrical currents and magnetized materials.
In a radio antenna's radiation pattern, the main lobe, or main beam, is the lobe containing the higher power.
Marine radars are X band or S band radars on ships, used to detect other ships and land obstacles, to provide bearing and distance for collision avoidance and navigation at sea.
A mast radiator (or radiating tower) is a radio mast or tower in which the entire structure functions as an antenna.
A mathematical model is a description of a system using mathematical concepts and language.
Medium frequency (MF) is the ITU designation for radio frequencies (RF) in the range of 300 kilohertz (kHz) to 3 megahertz (MHz).
Medium wave (MW) is the part of the medium frequency (MF) radio band used mainly for AM radio broadcasting.
Microstrip is a type of electrical transmission line which can be fabricated using printed circuit board technology, and is used to convey microwave-frequency signals.
In telecommunication, a microstrip antenna (also known as a printed antenna) usually means an antenna fabricated using microstrip techniques on a printed circuit board (PCB).
Microwaves are a form of electromagnetic radiation with wavelengths ranging from one meter to one millimeter; with frequencies between and.
A microwave radiometer (MWR) is a radiometer that measures energy emitted at millimetre-to-centimetre wavelengths (frequencies of 1–1000 GHz) known as microwaves.
A mobile broadband modem, also known as a connect card or data card, is a type of modem that allows a personal computer or a router to receive Internet access via a mobile broadband connection instead of using telephone or cable television lines.
A mobile phone, known as a cell phone in North America, is a portable telephone that can make and receive calls over a radio frequency link while the user is moving within a telephone service area.
A monopole antenna is a class of radio antenna consisting of a straight rod-shaped conductor, often mounted perpendicularly over some type of conductive surface, called a ground plane.
In wireless telecommunications, multipath is the propagation phenomenon that results in radio signals reaching the receiving antenna by two or more paths.
The near field and far field are regions of the electromagnetic field (EM) around an object, such as a transmitting antenna, or the result of radiation scattering off an object.
In radio electronics, a null is an area or vector in an antenna's radiation pattern where the signal cancels out almost entirely.
The Numerical Electromagnetics Code, or NEC, is a popular antenna modeling system for wire and surface antennas.
In radio communication, an omnidirectional antenna is a class of antenna which have an axis about which radio wave power is radiated symmetrically, and, upon that axis, is zero.
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.
A parabolic (or paraboloid or paraboloidal) reflector (or dish or mirror) is a reflective surface used to collect or project energy such as light, sound, or radio waves.
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.
A patch antenna is a type of radio antenna with a low profile, which can be mounted on a flat surface.
In electromagnetism, absolute permittivity, often simply called permittivity, usually denoted by the Greek letter ε (epsilon), is the measure of resistance that is encountered when forming an electric field in a particular medium.
Phase is the position of a point in time (an instant) on a waveform cycle.
A phase shift module is a microwave network module which provides a controllable phase shift of the RF signal.
In antenna theory, a phased array usually means an electronically scanned array; a computer-controlled array of antennas which creates a beam of radio waves which can be electronically steered to point in different directions, without moving the antennas.
Polarization (also polarisation) is a property applying to transverse waves that specifies the geometrical orientation of the oscillations.
A printed circuit board (PCB) mechanically supports and electrically connects electronic components or electrical components using conductive tracks, pads and other features etched from one or more sheet layers of copper laminated onto and/or between sheet layers of a non-conductive substrate.
In physics and engineering the quality factor or Q factor is a dimensionless parameter that describes how underdamped an oscillator or resonator is, and characterizes a resonator's bandwidth relative to its centre frequency.
A quad antenna is a type of directional wire radio antenna used on the HF and VHF bands.
Radar is an object-detection system that uses radio waves to determine the range, angle, or velocity of objects.
A radar speed gun (also radar gun and speed gun) is a device used to measure the speed of moving objects.
In RF engineering, radial has two distinct meanings, both referring to lines which radiate from (or intersect at) a radio antenna, but neither meaning is related to the other.
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.
Radiation resistance is that part of an antenna's feedpoint resistance that is caused by the radiation of electromagnetic waves from the antenna, as opposed to loss resistance (also called ohmic resistance) which generally causes the antenna to heat up.
Radio is the technology of using radio waves to carry information, such as sound, by systematically modulating properties of electromagnetic energy waves transmitted through space, such as their amplitude, frequency, phase, or pulse width.
Radio astronomy is a subfield of astronomy that studies celestial objects at radio frequencies.
Radio broadcasting is transmission by radio waves intended to reach a wide audience.
Radio frequency (RF) refers to oscillatory change in voltage or current in a circuit, waveguide or transmission line in the range extending from around twenty thousand times per second to around three hundred billion times per second, roughly between the upper limit of audio and the lower limit of infrared.
Radio masts and towers are, typically, tall structures designed to support antennas (also known as aerials) for telecommunications and broadcasting, including television.
In radio communications, a radio receiver (receiver or simply radio) is an electronic device that receives radio waves and converts the information carried by them to a usable form.
A radio station is a set of equipment necessary to carry on communication via radio waves.
A radio telescope is a specialized antenna and radio receiver used to receive radio waves from astronomical radio sources in the sky in radio astronomy.
Radio waves are a type of electromagnetic radiation with wavelengths in the electromagnetic spectrum longer than infrared light.
A random wire antenna is a radio antenna consisting of a long wire suspended above the ground, whose length does not bear a relation to the wavelength of the radio waves used, but is typically chosen more for convenience.
In classical electromagnetism, reciprocity refers to a variety of related theorems involving the interchange of time-harmonic electric current densities (sources) and the resulting electromagnetic fields in Maxwell's equations for time-invariant linear media under certain constraints.
In telecommunications and radar, a reflective array antenna is a class of directive antennas in which multiple driven elements are mounted in front of a flat surface designed to reflect the radio waves in a desired direction.
An antenna reflector is a device that reflects electromagnetic waves.
In optics, the refractive index or index of refraction of a material is a dimensionless number that describes how light propagates through that medium.
The relative permittivity of a material is its (absolute) permittivity expressed as a ratio relative to the permittivity of vacuum.
In electronics, a remote control or clicker is a component of an electronic device used to operate the device from a distance, usually wirelessly.
In physics, resonance is a phenomenon in which a vibrating system or external force drives another system to oscillate with greater amplitude at specific frequencies.
A resonator is a device or system that exhibits resonance or resonant behavior, that is, it naturally oscillates at some frequencies, called its resonant frequencies, with greater amplitude than at others.
A coaxial RF connector (radio frequency connector) is an electrical connector designed to work at radio frequencies in the multi-megahertz range.
A rhombic antenna is a broadband directional wire antenna co-invented by Edmond BruceUS Patent No.
In plane Euclidean geometry, a rhombus (plural rhombi or rhombuses) is a simple (non-self-intersecting) quadrilateral whose four sides all have the same length.
In mathematics and physics, the right-hand rule is a common mnemonic for understanding orientation conventions for the vector cross product in three dimensions.
In statistics and its applications, the root mean square (abbreviated RMS or rms) is defined as the square root of the mean square (the arithmetic mean of the squares of a set of numbers).
The rubber ducky antenna (or rubber duck aerial) is an electrically short monopole antenna that functions somewhat like a base-loaded whip antenna.
Satellite television is a service that delivers television programming to viewers by relaying it from a communications satellite orbiting the Earth directly to the viewer's location.
A sector antenna is a type of directional microwave antenna with a sector-shaped radiation pattern.
Selectivity is a measure of the performance of a radio receiver to respond only to the radio signal it is tuned to (such as a radio station) and reject other signals nearby in frequency, such as another broadcast on an adjacent channel.
A shortwave broadband antenna is a radio antenna, that without adjustment, can be used for transmission (and reception) of a shortwave radio channel chosen from greater part of the shortwave radio spectrum.
Shortwave radio is radio transmission using shortwave radio frequencies.
In antenna engineering, side lobes or sidelobes are the lobes (local maxima) of the far field radiation pattern that are not the main lobe.
Signal-to-noise ratio (abbreviated SNR or S/N) is a measure used in science and engineering that compares the level of a desired signal to the level of background noise.
In radio communication, skywave or skip refers to the propagation of radio waves reflected or refracted back toward Earth from the ionosphere, an electrically charged layer of the upper atmosphere.
A slot antenna consists of a metal surface, usually a flat plate, with one or more holes or slots cut out.
Smart antennas (also known as adaptive array antennas, digital antenna arrays, multiple antennas and, recently, MIMO) are antenna arrays with smart signal processing algorithms used to identify spatial signal signatures such as the direction of arrival (DOA) of the signal, and use them to calculate beamforming vectors which are used to track and locate the antenna beam on the mobile/target.
Specular reflection, also known as regular reflection, is the mirror-like reflection of waves, such as light, from a surface.
The speed of light in vacuum, commonly denoted, is a universal physical constant important in many areas of physics.
A sphere (from Greek σφαῖρα — sphaira, "globe, ball") is a perfectly round geometrical object in three-dimensional space that is the surface of a completely round ball (viz., analogous to the circular objects in two dimensions, where a "circle" circumscribes its "disk").
In physics, a standing wave – also known as a stationary wave – is a wave which oscillates in time but whose peak amplitude profile does not move in space.
In radio engineering and telecommunications, standing wave ratio (SWR) is a measure of impedance matching of loads to the characteristic impedance of a transmission line or waveguide.
In physics, a surface wave is a mechanical wave that propagates along the interface between differing media.
A T-antenna, T-aerial, flat-top antenna, or top-hat antenna is a capacitively loaded monopole wire radio antenna used in the VLF, LF, MF and shortwave bands.
Television (TV) is a telecommunication medium used for transmitting moving images in monochrome (black and white), or in colour, and in two or three dimensions and sound.
A television antenna, or TV aerial, is an antenna specifically designed for the reception of over-the-air broadcast television signals, which are transmitted at frequencies from about 41 to 250 MHz in the VHF band, and 470 to 960 MHz in the UHF band in different countries.
Terrestrial or broadcast television is a type of television broadcasting in which the television signal is transmitted by radio waves from the terrestrial (Earth based) transmitter of a television station to a TV receiver having an antenna.
Terrestrial Trunked Radio (TETRA; formerly known as Trans-European Trunked Radio), a European standard for a trunked radio system, is a professional mobile radio and two-way transceiver specification.
As originally stated in terms of DC resistive circuits only, Thévenin's theorem holds that: In circuit theory terms, the theorem allows any one-port network to be reduced to a single voltage source and a single impedance.
In geometry, a torus (plural tori) is a surface of revolution generated by revolving a circle in three-dimensional space about an axis coplanar with the circle.
A transformer is a static electrical device that transfers electrical energy between two or more circuits through electromagnetic induction.
In telecommunications, transmission (abbreviations: TX, Xmit) is the process of sending and propagating an analogue or digital information signal over a physical point-to-point or point-to-multipoint transmission medium, either wired, optical fiber or wireless.
In communications and electronic engineering, a transmission line is a specialized cable or other structure designed to conduct alternating current of radio frequency, that is, currents with a frequency high enough that their wave nature must be taken into account.
In electronics and telecommunications, a transmitter or radio transmitter is an electronic device which produces radio waves with an antenna.
A transverse wave is a moving wave that consists of oscillations occurring perpendicular (right angled) to the direction of energy transfer (or the propagation of the wave).
In radio and telecommunication, a traveling-wave antenna is a class of antenna that uses a traveling wave on a guiding structure as the main radiating mechanism.
A turnstile antenna, or crossed-dipole antenna, is a radio antenna consisting of a set of two identical dipole antennas mounted at right angles to each other and fed in phase quadrature; the two currents applied to the dipoles are 90° out of phase.
A two-way radio is a radio that can do both transmit and receive a signal (a transceiver), unlike a broadcast receiver which only receives content.
An umbrella antenna is a top-loaded electrically lengthened monopole antenna, consisting in most cases of a mast fed at the ground end, to which a number of radial wires are connected at the top, sloping downwards.
Vehicle audio is equipment installed in a car or other vehicle to provide in-car entertainment and information for the vehicle occupants.
Very low frequency or VLF is the ITU designation for radio frequencies (RF) in the range of 3 to 30 kilohertz (kHz), corresponding to wavelengths from 100 to 10 kilometers, respectively.
In physics, interference is a phenomenon in which two waves superpose to form a resultant wave of greater, lower, or the same amplitude.
A waveguide is a structure that guides waves, such as electromagnetic waves or sound, with minimal loss of energy by restricting expansion to one dimension or two.
In electromagnetics and communications engineering, the term waveguide may refer to any linear structure that conveys electromagnetic waves between its endpoints.
In physics, the wavelength is the spatial period of a periodic wave—the distance over which the wave's shape repeats.
A whip antenna is an antenna consisting of a straight flexible wire or rod.
Wi-Fi or WiFi is technology for radio wireless local area networking of devices based on the IEEE 802.11 standards.
Wind engineering is a subsets of mechanical engineering, structural engineering, meteorology, and applied physics to analyze the effects of wind in the natural and the built environment and studies the possible damage, inconvenience or benefits which may result from wind.
A wireless local area network (WLAN) is a wireless computer network that links two or more devices using wireless communication within a limited area such as a home, school, computer laboratory, or office building.
A Yagi–Uda antenna, commonly known as a Yagi antenna, is a directional antenna consisting of multiple parallel elements in a line, usually half-wave dipoles made of metal rods.
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