Slot Antenna Wikipedia
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From Wikipedia, the free encyclopedia In radio systems, many different antenna types are used with specialized properties for particular applications. Antennas can be classified in various ways. The list below groups together antennas under common operating principles, following the way antennas are classified in many engineering textbooks. If we cut a hole in an infinite conducting plane, and feed it with a voltage source across the center, we get a slot antenna: Because the slot is between the sides of the voltage source, the currents must travel around the slot. These currents traveling over a large distance are what make it an antenna. Jim cut a 40 inch/110.60 cm slot within a parabolic dish fed with a SO-239 jumper about 4.5 inches/11.43 cm from the end of the slot. The antenna is vertically polarized and should be able to work repeaters in your neighborhood.
*Slot Antenna Wikipedia Free
*Tv Antenna WikipediaLog-periodic antenna, 400–4000 MHzPart of a series onAntennas
*International Telecommunication Union
(Radio Regulations)
*Massive Multiple-input multiple-output (MIMO)
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. It was invented by John Dunlavy in 1952.
The most common form of log-periodic antenna is the log-periodic dipole array or LPDA, The LPDA consists of a number of half-wave dipoledriven elements of gradually increasing length, each consisting of a pair of metal rods. The dipoles are mounted close together in a line, connected in parallel to the feedline with alternating phase. Electrically, it simulates a series of two or three-element Yagi antennas connected together, each set tuned to a different frequency.
LPDA antennas look somewhat similar to Yagi antennas, in that they both consist of dipole rod elements mounted in a line along a support boom, but they work in very different ways. Adding elements to a Yagi increases its directionality, or gain, while adding elements to a LPDA increases its frequency response, or bandwidth.
One large application for LPDAs is in rooftop terrestrial television antennas, since they must have large bandwidth to cover the wide television bands of roughly 54–88 and 174–216 MHz in the VHF and 470–890 MHz in the UHF while also having high gain for adequate fringe reception. One widely used design for television reception combined a Yagi for UHF reception in front of a larger LPDA for VHF.Basic concept[edit]
The LPDA normally consists of a series of half wave dipole ’elements’ each consisting of a pair of metal rods, positioned along a support boom lying along the antenna axis. The elements are spaced at intervals following a logarithmic function of the frequency, known as d or sigma. The successive elements gradually decrease in length along the boom. The relationship between the lengths is a function known as tau. Sigma and tau are the key design elements of the LPDA design.[1][2] The radiation pattern of the antenna is unidirectional, with the main lobe along the axis of the boom, off the end with the shortest elements. Each dipole element is resonant at a wavelength approximately equal to twice its length. The bandwidth of the antenna, the frequency range over which it has maximum gain, is approximately between the resonant frequencies of the longest and shortest element.
Every element in the LPDA antenna is a driven element, that is, connected electrically to the feedline. A parallel wire transmission line usually runs along the central boom, and each successive element is connected in oppositephase to it. The feedline can often be seen zig-zagging across the support boom holding the elements.[2] Another common construction method is to use two parallel central support booms that also acts as the transmission line, mounting the dipoles on the alternate booms. Other forms of the log-periodic design replace the dipoles with the transmission line itself, forming the log-periodic zig-zag antenna.[3] Many other forms using the transmission wire as the active element also exist.[4]
The Yagi and the LPDA designs look very similar at first glance, as they both consist of a number of dipole elements mounted along a support boom. The Yagi, however, has only a single driven element connected to the transmission line, usually the second one from the back of the array, the remaining elements are parasitic. The Yagi antenna differs from the LPDA in having a very narrow bandwidth.
In general terms, at any given frequency the log-periodic design operates somewhat similar to a three-element Yagi antenna; the dipole element closest to resonant at the operating frequency acts as a driven element, with the two adjacent elements on either side as director and reflector to increase the gain, the shorter element in front acting as a director and the longer element behind as a reflector. However, the system is somewhat more complex than that, and all the elements contribute to some degree, so the gain for any given frequency is higher than a Yagi of the same dimensions as any one section of the log-periodic. However, a Yagi with the same number of elements as a log-periodic would have far higher gain, as all of those elements are improving the gain of a single driven element. In its use as a television antenna, it was common to combine a log-periodic design for VHF with a Yagi for UHF, with both halves being roughly equal in size. This resulted in much higher gain for UHF, typically on the order of 10 to 14 dB on the Yagi side and 6.5 dB for the log-periodic.[5] But this extra gain was needed anyway in order to make up for a number of problems with UHF signals.
It should be strictly noted that the log-periodic shape, according to the IEEE definition,[6][7] does not align with broadband property for antennas.[8][9] The broadband property of log-periodic antennas comes from its self-similarity. A planar log-periodic antenna can also be made self-complementary, such as logarithmic spiral antennas (which are not classified as log-periodic per se but among the frequency independent antennas that are also self-similar) or the log-periodic toothed design. Y. Mushiake found, for what he termed ’the simplest self-complementary planar antenna,’ a driving point impedance of η0/2=188.4 Ω at frequencies well within its bandwidth limits.[10][11][12]Log-periodic antenna, 250–2400 MHzLog periodic mounted for vertical polarization, covers 140–470 MHzLP television antenna 1963. Covers 54–88 MHz and 174–218 MHz. Slanted elements were used because on the upper band they operate at the 3rd harmonic.Wire Log-periodic monopole antenna.History[edit]
The log periodic antenna was invented by John Dunlavy in 1952 while working for the United States Air Force, but was not credited with it due to its ’Secret’ classification.[13] The University of Illinois at Urbana–Champaign had patented the Isbell and Mayes-Carrel antennas and licensed the design as a package exclusively to JFD Electronics in New York. Channel Master and Blonder Tongue Labs ignored the patents and produced a wide range of antennas based on this design. Lawsuits regarding the antenna patent which the UI Foundation lost, evolved into the 1971 Blonder-Tongue Doctrine.[14] This precedent governs patent litigation.[citation needed]Short wave broadcast antennas[edit]Wire log periodic transmitting antenna at international shortwave broadcasting station, Moosbrunn, Austria. Covers 6.1–23 MHzDiagram of a zig-zag shortwave LPA antenna, black shows metallic conductors, red shows insulating supports
The log periodic is commonly used as a transmitting antenna in high power shortwave broadcasting[15] stations because its broad bandwidth allows a single antenna to transmit on frequencies in multiple bands. The log-periodic zig-zag design with up to 16 sections has been used. These large antennas are typically designed to cover 6 to 26 MHz but even larger ones have been built which operate as low as 2 MHz. Power ratings are available up to 500 kW. Instead of the elements being driven in parallel, attached to a central transmission line, the elements are driven in series, adjacent elements connected at the outer edges. The antenna shown here would have about 14 dBi gain. An antenna array consisting of two such antennas, one above the other and driven in phase has a gain of up to 17 dBi. Being log-periodic, the antenna’s main characteristics (radiation pattern, gain, driving point impedance) are almost constant over its entire frequency range, with the match to a 300 Ω feed line achieving a standing wave ratio of better than 2:1 over that range.References[edit]
*^The Log-Periodic Dipole Array’
*^ ab’Log Periodic Dipole Array (LPDA)’. www.ewh.ieee.org.
*^’Log-periodic zig zag antenna’, US Patent 3355740
*^Photo Archive Of Antennas, Illinois Historic Archive
*^Davidson, David (2010). Computational Electromagnetics for RF and Microwave Engineering. Cambridge University Press. p. 178. ISBN9781139492812.
*^“Log-periodic antenna Any one of a class of antennas having a structural geometry such that its impedance and radiation characteristics repeat periodically as the logarithm of frequency.” (see The new IEEE Standard Dictionary of Electrical and Electronics Terms, 1993 ⓒ IEEE.)
*^“Log-periodic antenna Any one of a class of antennas having a structural geometry such that its impedance and radiation characteristics repeat periodically as the logarithm of frequency.” (see Acknowledgments, and footnote in page 1), Self-Complementary Antennas―Principle of Self-Complementarity for Constant Impedance―, by Y. Mushiake, Springer-Verlag London Ltd., London, 1996
*^Y. Mushiake, “Constant-impedance antennas’, J. IECE Japan, 48, 4, pp. 580-584, April 1965. (in Japanese)
*^’Y. Mushiake, Log-periodic structure provides no broad-band property for antennas.’ J. IEE Japan, 69, 3, p. 88, March 1949’. Sm.rim.or.jp. Retrieved 15 January 2014.
*^’Y. Mushiake, Origination of self-complementary structure and discovery of its constant-impedance property.’ J. IEE Japan, 69, 3, p. 88, March 1949. (in Japanese)’. Sm.rim.or.jp. Retrieved 31 January 2014.
*^’Y. Mushiake, Infinite freedom.’’’. Sm.rim.or.jp. Retrieved 15 January 2014.
*^V. H. Rumsey, Frequency independent antennas, Academic Press, New York and London. 1966. [p. 55]
*^https://www.stereophile.com/content/loudspeaker-designer-john-dunlavy-numbers-page-4
*^’Blonder–Tongue Doctrine Law and Legal Definition | USLegal, Inc’. definitions.uslegal.com.
*^’Antennas for the Shortwave Broadcaster’. www.antenna.be.Notes[edit]
This article incorporates public domain material from the General Services Administration document: ’Federal Standard 1037C’. (in support of MIL-STD-188)See also[edit]External links[edit]Retrieved from ’https://en.wikipedia.org/w/index.php?title=Log-periodic_antenna&oldid=996413013’
A slot antenna consists of a metal surface, usually a flat plate, with one or more holes or slots cut out.Wikipedia
*Antenna types
In radio systems, many different antenna types are used with specialized properties for particular applications. Antennas can be classified in various ways.Wikipedia
*Reflective array antenna
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. They are a type of array antenna.Wikipedia
*Horn antenna
Antenna that consists of a flaring metal waveguide shaped like a horn to direct radio waves in a beam. Horns are widely used as antennas at UHF and microwave frequencies, above 300 MHz.Wikipedia
*Vivaldi antenna
Co-planar broadband-antenna, which can be made from a solid piece of sheet metal, a printed circuit board, or from a dielectric plate metalized on one or both sides. Open space via a microstrip line or coaxial cable, and may be terminated with a sector-shaped area or a direct coaxial connection.Wikipedia Casino near rock hill ny aspca.
*Antenna (radio)
Antenna is the interface between radio waves propagating through space and electric currents moving in metal conductors, used with a transmitter or receiver. Electric current to the antenna’s terminals, and the antenna radiates the energy from the current as electromagnetic waves .Wikipedia
*Conformal antenna
Flat radio antenna which is designed to conform or follow some prescribed shape, for example a flat curving antenna which is mounted on or embedded in a curved surface. Conformal antennas were developed in the 1980s as avionics antennas integrated into the curving skin of military aircraft to reduce aerodynamic drag, replacing conventional antenna designs which project from the aircraft surface.Wikipedia
*Phased array
Electronically scanned array, a computer-controlled array of antennas which creates a beam of radio waves that can be electronically steered to point in different directions without moving the antennas. Array antenna, the radio frequency current from the transmitter is fed to the individual antennas with the correct phase relationship so that the radio waves from the separate antennas add together to increase the radiation in a desired direction, while cancelling to suppress radiation in undesired directions.Wikipedia
*Parabolic antenna
Antenna that uses a parabolic reflector, a curved surface with the cross-sectional shape of a parabola, to direct the radio waves. Shaped like a dish and is popularly called a dish antenna or parabolic dish.Wikipedia
*Loop antenna
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. Within this physical description there are two distinct antenna types.Wikipedia
*Dual-band blade antenna
Dual-Band Blade Antenna, a type of commercial RF ’Blade antenna’ that uses a ’plane and slot design’ to get efficient omni-directional coverage at two distinctly different RF bands. It has additive properties similar to a monopole antenna.Wikipedia
*Slotted line
Slotted lines are used for microwave measurements and consist of a movable probe inserted into a slot in a transmission line. Expensive microwave power meter.Wikipedia
*Helical antenna
Antenna consisting of one or more conducting wires wound in the form of a helix. In most cases, directional helical antennas are mounted over a ground plane, while omnidirectional designs may not be.Wikipedia
*Microwave antenna
Physical transmission device used to broadcast microwave transmissions between two or more locations. In addition to broadcasting, antennas are also used in radar, radio astronomy and electronic warfare.Wikipedia
*Slotted waveguide
Waveguide that is used as an antenna in microwave radar applications. Prior to its use in surface search radar, such systems used a parabolic segment reflector.Wikipedia
*Patch antenna
Type of radio antenna with a low profile, which can be mounted on a flat surface. It consists of a flat rectangular sheet or ’patch’ of metal, mounted over a larger sheet of metal called a ground plane.Wikipedia
*Turnstile antenna
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. The name reflects the notion the antenna looks like a turnstile when mounted horizontally.Wikipedia
*Antenna feed
Antenna feed refers to several slightly different parts of an antenna system: Converted to radiation; in a receiving antenna, the term refers to the parts of the system that convert the electric currents already collected from incoming radio waves into a specific voltage to current ratio needed at the receiver.Wikipedia
*Metamaterial antenna
Metamaterial antennas are a class of antennas which use metamaterials to increase performance of miniaturized (electrically small) antenna systems. To launch energy into free space.Wikipedia
*Passive radiator
Conductive element, typically a metal rod, which is not electrically connected to anything else. Connected to the radio receiver or transmitter through a feed line, and parasitic elements, which are not.Wikipedia
*Plasma antenna
Type of radio antenna currently in development in which plasma is used instead of the metal elements of a traditional antenna. A plasma antenna can be used for both transmission and reception.Wikipedia
*Antenna measurement
Antenna measurement techniques refers to the testing of antennas to ensure that the antenna meets specifications or simply to characterize it. Typical parameters of antennas are gain, radiation pattern, beamwidth, polarization, and impedance.Wikipedia
*Log-periodic antenna
Multi-element, directional antenna designed to operate over a wide band of frequencies. Invented by Dwight Isbell and Raymond DuHamel at the University of Illinois in 1958.Wikipedia
*Dipole antenna
Simplest and most widely used class of antenna. 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.Wikipedia
*Antenna array
Set of multiple connected antennas which work together as a single antenna, to transmit or receive radio waves. The individual antennas (called elements) are usually connected to a single receiver or transmitter by feedlines that feed the power to the elements in a specific phase relationship.Wikipedia
*Monopole antenna
Class of radio antenna consisting of a straight rod-shaped conductor, often mounted perpendicularly over some type of conductive surface, called a ground plane. Applied, or for receiving antennas the output signal to the receiver is taken, between the lower end of the monopole and the ground plane.Wikipedia
*Whip antenna
Antenna consisting of a straight flexible wire or rod. Connected to the radio receiver or transmitter.Wikipedia
*Squint (antenna)
Offset from the normal of the plane of the antenna. Change in the beam direction as a function of operating frequency, polarization, or orientation.Wikipedia
*Folded unipole antenna
Type of monopole antenna; it consists of a vertical metal rod or mast mounted over a conductive surface called a ground plane. Surrounded by a ’skirt’ of vertical wires electrically attached to the top of the mast.Wikipedia
*T-antenna
Capacitively loaded monopole wire radio antenna used in the VLF, LF, MF and shortwave bands. T-antennas are widely used as transmitting antennas for amateur radio stations, long wave and medium wave broadcasting stations.Wikipedia
*Driven element
Element in the antenna (typically a metal rod) which is electrically connected to the receiver or transmitter. Driven or excited by the RF current from the transmitter, and is the source of the radio waves.WikipediaSentences forSlot antennaSlot Antenna Wikipedia Free
*For television broadcasting specialized vertical radiators tha
https://diarynote-jp.indered.space
From Wikipedia, the free encyclopedia In radio systems, many different antenna types are used with specialized properties for particular applications. Antennas can be classified in various ways. The list below groups together antennas under common operating principles, following the way antennas are classified in many engineering textbooks. If we cut a hole in an infinite conducting plane, and feed it with a voltage source across the center, we get a slot antenna: Because the slot is between the sides of the voltage source, the currents must travel around the slot. These currents traveling over a large distance are what make it an antenna. Jim cut a 40 inch/110.60 cm slot within a parabolic dish fed with a SO-239 jumper about 4.5 inches/11.43 cm from the end of the slot. The antenna is vertically polarized and should be able to work repeaters in your neighborhood.
*Slot Antenna Wikipedia Free
*Tv Antenna WikipediaLog-periodic antenna, 400–4000 MHzPart of a series onAntennas
*International Telecommunication Union
(Radio Regulations)
*Massive Multiple-input multiple-output (MIMO)
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. It was invented by John Dunlavy in 1952.
The most common form of log-periodic antenna is the log-periodic dipole array or LPDA, The LPDA consists of a number of half-wave dipoledriven elements of gradually increasing length, each consisting of a pair of metal rods. The dipoles are mounted close together in a line, connected in parallel to the feedline with alternating phase. Electrically, it simulates a series of two or three-element Yagi antennas connected together, each set tuned to a different frequency.
LPDA antennas look somewhat similar to Yagi antennas, in that they both consist of dipole rod elements mounted in a line along a support boom, but they work in very different ways. Adding elements to a Yagi increases its directionality, or gain, while adding elements to a LPDA increases its frequency response, or bandwidth.
One large application for LPDAs is in rooftop terrestrial television antennas, since they must have large bandwidth to cover the wide television bands of roughly 54–88 and 174–216 MHz in the VHF and 470–890 MHz in the UHF while also having high gain for adequate fringe reception. One widely used design for television reception combined a Yagi for UHF reception in front of a larger LPDA for VHF.Basic concept[edit]
The LPDA normally consists of a series of half wave dipole ’elements’ each consisting of a pair of metal rods, positioned along a support boom lying along the antenna axis. The elements are spaced at intervals following a logarithmic function of the frequency, known as d or sigma. The successive elements gradually decrease in length along the boom. The relationship between the lengths is a function known as tau. Sigma and tau are the key design elements of the LPDA design.[1][2] The radiation pattern of the antenna is unidirectional, with the main lobe along the axis of the boom, off the end with the shortest elements. Each dipole element is resonant at a wavelength approximately equal to twice its length. The bandwidth of the antenna, the frequency range over which it has maximum gain, is approximately between the resonant frequencies of the longest and shortest element.
Every element in the LPDA antenna is a driven element, that is, connected electrically to the feedline. A parallel wire transmission line usually runs along the central boom, and each successive element is connected in oppositephase to it. The feedline can often be seen zig-zagging across the support boom holding the elements.[2] Another common construction method is to use two parallel central support booms that also acts as the transmission line, mounting the dipoles on the alternate booms. Other forms of the log-periodic design replace the dipoles with the transmission line itself, forming the log-periodic zig-zag antenna.[3] Many other forms using the transmission wire as the active element also exist.[4]
The Yagi and the LPDA designs look very similar at first glance, as they both consist of a number of dipole elements mounted along a support boom. The Yagi, however, has only a single driven element connected to the transmission line, usually the second one from the back of the array, the remaining elements are parasitic. The Yagi antenna differs from the LPDA in having a very narrow bandwidth.
In general terms, at any given frequency the log-periodic design operates somewhat similar to a three-element Yagi antenna; the dipole element closest to resonant at the operating frequency acts as a driven element, with the two adjacent elements on either side as director and reflector to increase the gain, the shorter element in front acting as a director and the longer element behind as a reflector. However, the system is somewhat more complex than that, and all the elements contribute to some degree, so the gain for any given frequency is higher than a Yagi of the same dimensions as any one section of the log-periodic. However, a Yagi with the same number of elements as a log-periodic would have far higher gain, as all of those elements are improving the gain of a single driven element. In its use as a television antenna, it was common to combine a log-periodic design for VHF with a Yagi for UHF, with both halves being roughly equal in size. This resulted in much higher gain for UHF, typically on the order of 10 to 14 dB on the Yagi side and 6.5 dB for the log-periodic.[5] But this extra gain was needed anyway in order to make up for a number of problems with UHF signals.
It should be strictly noted that the log-periodic shape, according to the IEEE definition,[6][7] does not align with broadband property for antennas.[8][9] The broadband property of log-periodic antennas comes from its self-similarity. A planar log-periodic antenna can also be made self-complementary, such as logarithmic spiral antennas (which are not classified as log-periodic per se but among the frequency independent antennas that are also self-similar) or the log-periodic toothed design. Y. Mushiake found, for what he termed ’the simplest self-complementary planar antenna,’ a driving point impedance of η0/2=188.4 Ω at frequencies well within its bandwidth limits.[10][11][12]Log-periodic antenna, 250–2400 MHzLog periodic mounted for vertical polarization, covers 140–470 MHzLP television antenna 1963. Covers 54–88 MHz and 174–218 MHz. Slanted elements were used because on the upper band they operate at the 3rd harmonic.Wire Log-periodic monopole antenna.History[edit]
The log periodic antenna was invented by John Dunlavy in 1952 while working for the United States Air Force, but was not credited with it due to its ’Secret’ classification.[13] The University of Illinois at Urbana–Champaign had patented the Isbell and Mayes-Carrel antennas and licensed the design as a package exclusively to JFD Electronics in New York. Channel Master and Blonder Tongue Labs ignored the patents and produced a wide range of antennas based on this design. Lawsuits regarding the antenna patent which the UI Foundation lost, evolved into the 1971 Blonder-Tongue Doctrine.[14] This precedent governs patent litigation.[citation needed]Short wave broadcast antennas[edit]Wire log periodic transmitting antenna at international shortwave broadcasting station, Moosbrunn, Austria. Covers 6.1–23 MHzDiagram of a zig-zag shortwave LPA antenna, black shows metallic conductors, red shows insulating supports
The log periodic is commonly used as a transmitting antenna in high power shortwave broadcasting[15] stations because its broad bandwidth allows a single antenna to transmit on frequencies in multiple bands. The log-periodic zig-zag design with up to 16 sections has been used. These large antennas are typically designed to cover 6 to 26 MHz but even larger ones have been built which operate as low as 2 MHz. Power ratings are available up to 500 kW. Instead of the elements being driven in parallel, attached to a central transmission line, the elements are driven in series, adjacent elements connected at the outer edges. The antenna shown here would have about 14 dBi gain. An antenna array consisting of two such antennas, one above the other and driven in phase has a gain of up to 17 dBi. Being log-periodic, the antenna’s main characteristics (radiation pattern, gain, driving point impedance) are almost constant over its entire frequency range, with the match to a 300 Ω feed line achieving a standing wave ratio of better than 2:1 over that range.References[edit]
*^The Log-Periodic Dipole Array’
*^ ab’Log Periodic Dipole Array (LPDA)’. www.ewh.ieee.org.
*^’Log-periodic zig zag antenna’, US Patent 3355740
*^Photo Archive Of Antennas, Illinois Historic Archive
*^Davidson, David (2010). Computational Electromagnetics for RF and Microwave Engineering. Cambridge University Press. p. 178. ISBN9781139492812.
*^“Log-periodic antenna Any one of a class of antennas having a structural geometry such that its impedance and radiation characteristics repeat periodically as the logarithm of frequency.” (see The new IEEE Standard Dictionary of Electrical and Electronics Terms, 1993 ⓒ IEEE.)
*^“Log-periodic antenna Any one of a class of antennas having a structural geometry such that its impedance and radiation characteristics repeat periodically as the logarithm of frequency.” (see Acknowledgments, and footnote in page 1), Self-Complementary Antennas―Principle of Self-Complementarity for Constant Impedance―, by Y. Mushiake, Springer-Verlag London Ltd., London, 1996
*^Y. Mushiake, “Constant-impedance antennas’, J. IECE Japan, 48, 4, pp. 580-584, April 1965. (in Japanese)
*^’Y. Mushiake, Log-periodic structure provides no broad-band property for antennas.’ J. IEE Japan, 69, 3, p. 88, March 1949’. Sm.rim.or.jp. Retrieved 15 January 2014.
*^’Y. Mushiake, Origination of self-complementary structure and discovery of its constant-impedance property.’ J. IEE Japan, 69, 3, p. 88, March 1949. (in Japanese)’. Sm.rim.or.jp. Retrieved 31 January 2014.
*^’Y. Mushiake, Infinite freedom.’’’. Sm.rim.or.jp. Retrieved 15 January 2014.
*^V. H. Rumsey, Frequency independent antennas, Academic Press, New York and London. 1966. [p. 55]
*^https://www.stereophile.com/content/loudspeaker-designer-john-dunlavy-numbers-page-4
*^’Blonder–Tongue Doctrine Law and Legal Definition | USLegal, Inc’. definitions.uslegal.com.
*^’Antennas for the Shortwave Broadcaster’. www.antenna.be.Notes[edit]
This article incorporates public domain material from the General Services Administration document: ’Federal Standard 1037C’. (in support of MIL-STD-188)See also[edit]External links[edit]Retrieved from ’https://en.wikipedia.org/w/index.php?title=Log-periodic_antenna&oldid=996413013’
A slot antenna consists of a metal surface, usually a flat plate, with one or more holes or slots cut out.Wikipedia
*Antenna types
In radio systems, many different antenna types are used with specialized properties for particular applications. Antennas can be classified in various ways.Wikipedia
*Reflective array antenna
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. They are a type of array antenna.Wikipedia
*Horn antenna
Antenna that consists of a flaring metal waveguide shaped like a horn to direct radio waves in a beam. Horns are widely used as antennas at UHF and microwave frequencies, above 300 MHz.Wikipedia
*Vivaldi antenna
Co-planar broadband-antenna, which can be made from a solid piece of sheet metal, a printed circuit board, or from a dielectric plate metalized on one or both sides. Open space via a microstrip line or coaxial cable, and may be terminated with a sector-shaped area or a direct coaxial connection.Wikipedia Casino near rock hill ny aspca.
*Antenna (radio)
Antenna is the interface between radio waves propagating through space and electric currents moving in metal conductors, used with a transmitter or receiver. Electric current to the antenna’s terminals, and the antenna radiates the energy from the current as electromagnetic waves .Wikipedia
*Conformal antenna
Flat radio antenna which is designed to conform or follow some prescribed shape, for example a flat curving antenna which is mounted on or embedded in a curved surface. Conformal antennas were developed in the 1980s as avionics antennas integrated into the curving skin of military aircraft to reduce aerodynamic drag, replacing conventional antenna designs which project from the aircraft surface.Wikipedia
*Phased array
Electronically scanned array, a computer-controlled array of antennas which creates a beam of radio waves that can be electronically steered to point in different directions without moving the antennas. Array antenna, the radio frequency current from the transmitter is fed to the individual antennas with the correct phase relationship so that the radio waves from the separate antennas add together to increase the radiation in a desired direction, while cancelling to suppress radiation in undesired directions.Wikipedia
*Parabolic antenna
Antenna that uses a parabolic reflector, a curved surface with the cross-sectional shape of a parabola, to direct the radio waves. Shaped like a dish and is popularly called a dish antenna or parabolic dish.Wikipedia
*Loop antenna
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. Within this physical description there are two distinct antenna types.Wikipedia
*Dual-band blade antenna
Dual-Band Blade Antenna, a type of commercial RF ’Blade antenna’ that uses a ’plane and slot design’ to get efficient omni-directional coverage at two distinctly different RF bands. It has additive properties similar to a monopole antenna.Wikipedia
*Slotted line
Slotted lines are used for microwave measurements and consist of a movable probe inserted into a slot in a transmission line. Expensive microwave power meter.Wikipedia
*Helical antenna
Antenna consisting of one or more conducting wires wound in the form of a helix. In most cases, directional helical antennas are mounted over a ground plane, while omnidirectional designs may not be.Wikipedia
*Microwave antenna
Physical transmission device used to broadcast microwave transmissions between two or more locations. In addition to broadcasting, antennas are also used in radar, radio astronomy and electronic warfare.Wikipedia
*Slotted waveguide
Waveguide that is used as an antenna in microwave radar applications. Prior to its use in surface search radar, such systems used a parabolic segment reflector.Wikipedia
*Patch antenna
Type of radio antenna with a low profile, which can be mounted on a flat surface. It consists of a flat rectangular sheet or ’patch’ of metal, mounted over a larger sheet of metal called a ground plane.Wikipedia
*Turnstile antenna
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. The name reflects the notion the antenna looks like a turnstile when mounted horizontally.Wikipedia
*Antenna feed
Antenna feed refers to several slightly different parts of an antenna system: Converted to radiation; in a receiving antenna, the term refers to the parts of the system that convert the electric currents already collected from incoming radio waves into a specific voltage to current ratio needed at the receiver.Wikipedia
*Metamaterial antenna
Metamaterial antennas are a class of antennas which use metamaterials to increase performance of miniaturized (electrically small) antenna systems. To launch energy into free space.Wikipedia
*Passive radiator
Conductive element, typically a metal rod, which is not electrically connected to anything else. Connected to the radio receiver or transmitter through a feed line, and parasitic elements, which are not.Wikipedia
*Plasma antenna
Type of radio antenna currently in development in which plasma is used instead of the metal elements of a traditional antenna. A plasma antenna can be used for both transmission and reception.Wikipedia
*Antenna measurement
Antenna measurement techniques refers to the testing of antennas to ensure that the antenna meets specifications or simply to characterize it. Typical parameters of antennas are gain, radiation pattern, beamwidth, polarization, and impedance.Wikipedia
*Log-periodic antenna
Multi-element, directional antenna designed to operate over a wide band of frequencies. Invented by Dwight Isbell and Raymond DuHamel at the University of Illinois in 1958.Wikipedia
*Dipole antenna
Simplest and most widely used class of antenna. 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.Wikipedia
*Antenna array
Set of multiple connected antennas which work together as a single antenna, to transmit or receive radio waves. The individual antennas (called elements) are usually connected to a single receiver or transmitter by feedlines that feed the power to the elements in a specific phase relationship.Wikipedia
*Monopole antenna
Class of radio antenna consisting of a straight rod-shaped conductor, often mounted perpendicularly over some type of conductive surface, called a ground plane. Applied, or for receiving antennas the output signal to the receiver is taken, between the lower end of the monopole and the ground plane.Wikipedia
*Whip antenna
Antenna consisting of a straight flexible wire or rod. Connected to the radio receiver or transmitter.Wikipedia
*Squint (antenna)
Offset from the normal of the plane of the antenna. Change in the beam direction as a function of operating frequency, polarization, or orientation.Wikipedia
*Folded unipole antenna
Type of monopole antenna; it consists of a vertical metal rod or mast mounted over a conductive surface called a ground plane. Surrounded by a ’skirt’ of vertical wires electrically attached to the top of the mast.Wikipedia
*T-antenna
Capacitively loaded monopole wire radio antenna used in the VLF, LF, MF and shortwave bands. T-antennas are widely used as transmitting antennas for amateur radio stations, long wave and medium wave broadcasting stations.Wikipedia
*Driven element
Element in the antenna (typically a metal rod) which is electrically connected to the receiver or transmitter. Driven or excited by the RF current from the transmitter, and is the source of the radio waves.WikipediaSentences forSlot antennaSlot Antenna Wikipedia Free
*For television broadcasting specialized vertical radiators tha
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