Dipole - Revision history

TimVK4YEH: fixed harmonic error as per talk page

2011-01-19T21:22:59Z

fixed harmonic error as per talk page

← Older revision		Revision as of 14:22, 19 January 2011
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	[[Image:vk4yeh_folded_dipole.jpg\|550px]]		[[Image:vk4yeh_folded_dipole.jpg\|550px]]

	Another advantage of a folded dipole is that it has a wide usable bandwidth, allowing it to cover more of the band. However, folded dipoles cannot be used as part of a [[dipole#fan dipole\|fan dipole]], and unlike conventional single-wire dipoles, they cannot be used on their odd harmonics. (Both of these limitations occur because conventional dipoles have higher [[impedance]] away from their resonant frequencies and reach minimum [[impedance]] at [[resonance]], while folded dipoles have lower [[impedance]] away from [[resonance]] and approach maximum [[impedance]] at [[resonance]]. At DC, a folded dipole is a direct short across the feedpoint, while a conventional dipole is an open circuit.)		Another advantage of a folded dipole is that it has a wide usable bandwidth, allowing it to cover more of the band. However, folded dipoles cannot be used as part of a [[dipole#fan dipole\|fan dipole]], and unlike conventional single-wire dipoles, they cannot be used on their even harmonics - they are resonant on odd harmonics. (Both of these limitations occur because conventional dipoles have higher [[impedance]] away from their resonant frequencies and reach minimum [[impedance]] at [[resonance]], while folded dipoles have lower [[impedance]] away from [[resonance]] and approach maximum [[impedance]] at [[resonance]]. At DC, a folded dipole is a direct short across the feedpoint, while a conventional dipole is an open circuit.)

	== Fan Dipole ==		== Fan Dipole ==

TheAnarcat: /* External links */

2010-11-22T04:43:46Z

External links

← Older revision		Revision as of 21:43, 21 November 2010
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	* [http://www.eham.net/articles/24060 Your First Dipole] - eham.net		* [http://www.eham.net/articles/24060 Your First Dipole] - eham.net
	* [http://www.k7mem.150m.com/Electronic_Notebook/antennas/dipole.html Center-Fed Half-Wave Dipole (3-30MHz) by Martin E. Meserve] - good examples on how to build a dipole and associated baluns		* [http://www.k7mem.150m.com/Electronic_Notebook/antennas/dipole.html Center-Fed Half-Wave Dipole (3-30MHz) by Martin E. Meserve] - good examples on how to build a dipole and associated baluns
			* [http://degood.org/coaxtrap/ An Attic Coaxial-Cable Trap Dipole for 10, 15, 20, 30, 40, and 80 Meters]



	{{antennas}}		{{antennas}}

TheAnarcat at 19:16, 7 November 2010

2010-11-07T19:16:21Z

← Older revision		Revision as of 12:16, 7 November 2010
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	* [http://www.ehow.com/how_4528486_that-doesnt-require-antenna-tuner.html How to Build a Simple But Effective Dipole Antenna That Doesn't Require an Antenna Tune] - ehow.com		* [http://www.ehow.com/how_4528486_that-doesnt-require-antenna-tuner.html How to Build a Simple But Effective Dipole Antenna That Doesn't Require an Antenna Tune] - ehow.com
	* [http://www.eham.net/articles/24060 Your First Dipole] - eham.net		* [http://www.eham.net/articles/24060 Your First Dipole] - eham.net
	* [http://www.k7mem.150m.com/Electronic_Notebook/antennas/dipole.html ~~enter~~-Fed Half-Wave Dipole (3-30MHz) by Martin E. Meserve] - good examples on how to build a dipole and associated baluns		* [http://www.k7mem.150m.com/Electronic_Notebook/antennas/dipole.html Center-Fed Half-Wave Dipole (3-30MHz) by Martin E. Meserve] - good examples on how to build a dipole and associated baluns

	{{antennas}}		{{antennas}}

TheAnarcat at 19:15, 7 November 2010

2010-11-07T19:15:51Z

← Older revision		Revision as of 12:15, 7 November 2010
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	* [http://www.ehow.com/how_4528486_that-doesnt-require-antenna-tuner.html How to Build a Simple But Effective Dipole Antenna That Doesn't Require an Antenna Tune] - ehow.com		* [http://www.ehow.com/how_4528486_that-doesnt-require-antenna-tuner.html How to Build a Simple But Effective Dipole Antenna That Doesn't Require an Antenna Tune] - ehow.com
	* [http://www.eham.net/articles/24060 Your First Dipole] - eham.net		* [http://www.eham.net/articles/24060 Your First Dipole] - eham.net
			* [http://www.k7mem.150m.com/Electronic_Notebook/antennas/dipole.html enter-Fed Half-Wave Dipole (3-30MHz) by Martin E. Meserve] - good examples on how to build a dipole and associated baluns

	{{antennas}}		{{antennas}}

TheAnarcat at 18:57, 7 November 2010

2010-11-07T18:57:39Z

← Older revision		Revision as of 11:57, 7 November 2010
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	Dipole antennas are "two-sided' in that they are fed from a point between the two ends. In its simplest form, a dipole will be centre-fed, with the total length being a half-wavelength at the frequency of transmission.		Dipole antennas are "two-sided' in that they are fed from a point between the two ends. In its simplest form, a dipole will be centre-fed, with the total length being a half-wavelength at the frequency of transmission.

			''Main article: [[Wikipedia:Dipole_antenna]]''

	== Centre-fed half-wave dipole ==		== Centre-fed half-wave dipole ==

TheAnarcat: clarify that while a dipole can be balanced, the common setup isn't

2010-11-07T18:54:52Z

clarify that while a dipole can be balanced, the common setup isn't

← Older revision		Revision as of 11:54, 7 November 2010
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	[[Image:Vk4yeh_Dipole_antenna.png]]		[[Image:Vk4yeh_Dipole_antenna.png]]

			However, in the above diagram, the coaxial cable is not a balanced feeder because the outer shield is grounded and therefore the feedline itself can radiate. This can be solved by using a [[balun]].

	These 1/2 wave dipoles can be used on their odd [[harmonics]] as well as their [[fundamental frequency\|fundamental resonant frequencies]]. For example, the amateur [[40 metres\|40 metre band]] begins at 7 MHz. The 3rd harmonic is 3 x 7 = 21 MHz, where the [[15 metres\|15 metre band]] begins. Thus a centre-fed dipole that is a half-wavelength long at [[40 metres]] (approximately 20 metres long, or 66 feet) can also be used as a [[15 metres\|15 metre]] antenna.		These 1/2 wave dipoles can be used on their odd [[harmonics]] as well as their [[fundamental frequency\|fundamental resonant frequencies]]. For example, the amateur [[40 metres\|40 metre band]] begins at 7 MHz. The 3rd harmonic is 3 x 7 = 21 MHz, where the [[15 metres\|15 metre band]] begins. Thus a centre-fed dipole that is a half-wavelength long at [[40 metres]] (approximately 20 metres long, or 66 feet) can also be used as a [[15 metres\|15 metre]] antenna.

TheAnarcat at 03:49, 5 November 2010

2010-11-05T03:49:35Z

← Older revision		Revision as of 20:49, 4 November 2010
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	There are several different variations on the G5RV. The most well-known is fed through 450-ohm [[ladder line]] 10.6 metres (34.8 feet) long, with one end of the ladder line connected at the centre-feed point of the antenna and the other connected through a [[balun]] to 50-ohm [[Coaxial Cable]] [[feedline]]. An alternative is to run [[balanced feedline]] (such as [[twin-lead]] or [[ladder line]]) all the way from the antenna [[feedpoint]] to the [[antenna tuner]]. The latter arrangement can be very effective, but not all lengths of [[feedline]] will tune properly. (See detailed discussion on [[feedline\|feedlines]].) Standard G5RV antennas are 31 metres (102 feet) long (excluding feedline and matching section length), and can be used on [[80 metres\|80]], [[40 metres\|40]], [[20 metres\|20]], [[15 metres\|15]], and [[10 metres]]. A half-length G5RV 51 feet long can be used on [[40 metres\|40]], [[20 metres\|20]], [[15 metres\|15]], and [[10 metres\|10]]; this variation is known as the '''G5RV jr'''.		There are several different variations on the G5RV. The most well-known is fed through 450-ohm [[ladder line]] 10.6 metres (34.8 feet) long, with one end of the ladder line connected at the centre-feed point of the antenna and the other connected through a [[balun]] to 50-ohm [[Coaxial Cable]] [[feedline]]. An alternative is to run [[balanced feedline]] (such as [[twin-lead]] or [[ladder line]]) all the way from the antenna [[feedpoint]] to the [[antenna tuner]]. The latter arrangement can be very effective, but not all lengths of [[feedline]] will tune properly. (See detailed discussion on [[feedline\|feedlines]].) Standard G5RV antennas are 31 metres (102 feet) long (excluding feedline and matching section length), and can be used on [[80 metres\|80]], [[40 metres\|40]], [[20 metres\|20]], [[15 metres\|15]], and [[10 metres]]. A half-length G5RV 51 feet long can be used on [[40 metres\|40]], [[20 metres\|20]], [[15 metres\|15]], and [[10 metres\|10]]; this variation is known as the '''G5RV jr'''.

	The antenna can be installed as a horizontal dipole or an inverted V. If configured as such, the included angle at the apex should exceed 120 degrees. This means, for example, that a junior G5RV will be elevated at most 13 feet higher than the ends of the dipole.		The antenna can be installed as a horizontal dipole or an inverted V. If configured as such, the included angle at the apex should exceed 120 degrees. This means, for example, that a junior G5RV will be elevated at most 13 feet higher than the ends of the dipole. To calculate this, you can use the following, where we split the triangle created by the inverted V in two square triangles to apply simple [[Wikipedia:Trigonometric_functions\|trigonometry]]:

			<math>\frac{height}{hypotenuse} = \cos(half of included angle)</math>

			hence:

			<math>height = hypothenuse * \cos(half of included angle) = \frac{51}{2} * \cos(\frac{120}{2}) = 26.5 * \cos(60) = 13.25</math>

	=== Reviews and references ===		=== Reviews and references ===

TheAnarcat: /* G5RV antenna */

2010-11-05T03:27:19Z

G5RV antenna

← Older revision		Revision as of 20:27, 4 November 2010
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	There are several different variations on the G5RV. The most well-known is fed through 450-ohm [[ladder line]] 10.6 metres (34.8 feet) long, with one end of the ladder line connected at the centre-feed point of the antenna and the other connected through a [[balun]] to 50-ohm [[Coaxial Cable]] [[feedline]]. An alternative is to run [[balanced feedline]] (such as [[twin-lead]] or [[ladder line]]) all the way from the antenna [[feedpoint]] to the [[antenna tuner]]. The latter arrangement can be very effective, but not all lengths of [[feedline]] will tune properly. (See detailed discussion on [[feedline\|feedlines]].) Standard G5RV antennas are 31 metres (102 feet) long (excluding feedline and matching section length), and can be used on [[80 metres\|80]], [[40 metres\|40]], [[20 metres\|20]], [[15 metres\|15]], and [[10 metres]]. A half-length G5RV 51 feet long can be used on [[40 metres\|40]], [[20 metres\|20]], [[15 metres\|15]], and [[10 metres\|10]]; this variation is known as the '''G5RV jr'''.		There are several different variations on the G5RV. The most well-known is fed through 450-ohm [[ladder line]] 10.6 metres (34.8 feet) long, with one end of the ladder line connected at the centre-feed point of the antenna and the other connected through a [[balun]] to 50-ohm [[Coaxial Cable]] [[feedline]]. An alternative is to run [[balanced feedline]] (such as [[twin-lead]] or [[ladder line]]) all the way from the antenna [[feedpoint]] to the [[antenna tuner]]. The latter arrangement can be very effective, but not all lengths of [[feedline]] will tune properly. (See detailed discussion on [[feedline\|feedlines]].) Standard G5RV antennas are 31 metres (102 feet) long (excluding feedline and matching section length), and can be used on [[80 metres\|80]], [[40 metres\|40]], [[20 metres\|20]], [[15 metres\|15]], and [[10 metres]]. A half-length G5RV 51 feet long can be used on [[40 metres\|40]], [[20 metres\|20]], [[15 metres\|15]], and [[10 metres\|10]]; this variation is known as the '''G5RV jr'''.

	The antenna can be installed as a horizontal dipole or an inverted V. If configured as such, the included angle at the apex should exceed 120 degrees.		The antenna can be installed as a horizontal dipole or an inverted V. If configured as such, the included angle at the apex should exceed 120 degrees. This means, for example, that a junior G5RV will be elevated at most 13 feet higher than the ends of the dipole.

	=== Reviews and references ===		=== Reviews and references ===

TheAnarcat: try to make this more readable by adding an intro and shuffling sections around

2010-11-05T03:23:45Z

try to make this more readable by adding an intro and shuffling sections around

← Older revision		Revision as of 20:23, 4 November 2010
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			Dipoles are one of the first antennas ever created. Indeed, [[Hertz]] himself is often credited as the inventor of the dipole, in 1886). It's also the simplest antenna designs out there, while staying very powerful and useful, in all bands.

	Dipole antennas are "two-sided' in that they are fed from a point between the two ends. In its simplest form, a dipole will be centre-fed, with the total length being a half-wavelength at the frequency of transmission.		Dipole antennas are "two-sided' in that they are fed from a point between the two ends. In its simplest form, a dipole will be centre-fed, with the total length being a half-wavelength at the frequency of transmission.

	== Centre-fed half-wave dipole ==		== Centre-fed half-wave dipole ==

			Half-wave centre-fed dipoles with each leg 1/4 wavelength long are perhaps the most common antennas used in amateur radio. They are an example of a [[balanced antenna]] which does not require a [[centerpoise]] or other [[RF ground]].

	[[Image:Vk4yeh_Dipole_antenna.png]]		[[Image:Vk4yeh_Dipole_antenna.png]]

			These 1/2 wave dipoles can be used on their odd [[harmonics]] as well as their [[fundamental frequency\|fundamental resonant frequencies]]. For example, the amateur [[40 metres\|40 metre band]] begins at 7 MHz. The 3rd harmonic is 3 x 7 = 21 MHz, where the [[15 metres\|15 metre band]] begins. Thus a centre-fed dipole that is a half-wavelength long at [[40 metres]] (approximately 20 metres long, or 66 feet) can also be used as a [[15 metres\|15 metre]] antenna.

	Dipole length for resonance is calculated using either:		Dipole length for resonance is calculated using either:
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	<math>L = \frac {142.5}{frequency(MHz)}</math> for total length in metres.		<math>L = \frac {142.5}{frequency(MHz)}</math> for total length in metres.

	Half-wave centre-fed dipoles with each leg 1/4 wavelength long are perhaps the most common antennas used in amateur radio. They are an example of a [[balanced antenna]] which does not require a [[centerpoise]] or other [[RF ground]].

	These 1/2 wave dipoles can be used on their odd [[harmonics]] as well as their [[fundamental frequency\|fundamental resonant frequencies]]. For example, the amateur [[40 metres\|40 metre band]] begins at 7 MHz. The 3rd harmonic is 3 x 7 = 21 MHz, where the [[15 metres\|15 metre band]] begins. Thus a centre-fed dipole that is a half-wavelength long at [[40 metres]] (approximately 20 metres long, or 66 feet) can also be used as a [[15 metres\|15 metre]] antenna.

	== Off-centre-fed dipole (OCF dipole) ==		== Off-centre-fed dipole (OCF dipole) ==
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	== G5RV antenna ==		== G5RV antenna ==

			Although the G5RV is not a 1/2 wave dipole like those described above, this antenna (invented by Louis Varney, callsign G5RV) shares some physical characteristics with a centre-fed dipole. The main difference between a dipole and G5RV is that the transmission line of a G5RV is part of the [[impedance matching\|matching]] section that allows operation over a number of bands. Although the G5RV can be used on [[20 metres]] without an [[antenna tuner]], a tuner is necessary to use it on other bands.

	[[Image:G5RV.jpg \| 700px]]		[[Image:G5RV.jpg \| 700px]]

	Although the G5RV is not a 1/2 wave dipole like those described above, this antenna (invented by Louis Varney, callsign G5RV) shares some physical characteristics with a centre-fed dipole. The main difference between a dipole and G5RV is that the transmission line of a G5RV is part of the [[impedance matching\|matching]] section that allows operation over a number of bands. Although the G5RV can be used on [[20 metres]] without an [[antenna tuner]], a tuner is necessary to use it on other bands.

	There are several different variations on the G5RV. The most well-known is fed through 450-ohm [[ladder line]] 10.6 metres (34.8 feet) long, with one end of the ladder line connected at the centre-feed point of the antenna and the other connected through a [[balun]] to 50-ohm [[Coaxial Cable]] [[feedline]]. An alternative is to run [[balanced feedline]] (such as [[twin-lead]] or [[ladder line]]) all the way from the antenna [[feedpoint]] to the [[antenna tuner]]. The latter arrangement can be very effective, but not all lengths of [[feedline]] will tune properly. (See detailed discussion on [[feedline\|feedlines]].) Standard G5RV antennas are 31 metres (102 feet) long (excluding feedline and matching section length), and can be used on [[80 metres\|80]], [[40 metres\|40]], [[20 metres\|20]], [[15 metres\|15]], and [[10 metres]]. A half-length G5RV 51 feet long can be used on [[40 metres\|40]], [[20 metres\|20]], [[15 metres\|15]], and [[10 metres\|10]]; this variation is known as the '''G5RV jr'''.		There are several different variations on the G5RV. The most well-known is fed through 450-ohm [[ladder line]] 10.6 metres (34.8 feet) long, with one end of the ladder line connected at the centre-feed point of the antenna and the other connected through a [[balun]] to 50-ohm [[Coaxial Cable]] [[feedline]]. An alternative is to run [[balanced feedline]] (such as [[twin-lead]] or [[ladder line]]) all the way from the antenna [[feedpoint]] to the [[antenna tuner]]. The latter arrangement can be very effective, but not all lengths of [[feedline]] will tune properly. (See detailed discussion on [[feedline\|feedlines]].) Standard G5RV antennas are 31 metres (102 feet) long (excluding feedline and matching section length), and can be used on [[80 metres\|80]], [[40 metres\|40]], [[20 metres\|20]], [[15 metres\|15]], and [[10 metres]]. A half-length G5RV 51 feet long can be used on [[40 metres\|40]], [[20 metres\|20]], [[15 metres\|15]], and [[10 metres\|10]]; this variation is known as the '''G5RV jr'''.

TheAnarcat: see also below

2010-11-05T03:20:41Z

← Older revision		Revision as of 20:20, 4 November 2010
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	~~Related wiki pages : [[Antennas]], [[gain]], [[SWR]], [[Propagation]]~~

	Dipole antennas are "two-sided' in that they are fed from a point between the two ends. In its simplest form, a dipole will be centre-fed, with the total length being a half-wavelength at the frequency of transmission.		Dipole antennas are "two-sided' in that they are fed from a point between the two ends. In its simplest form, a dipole will be centre-fed, with the total length being a half-wavelength at the frequency of transmission.

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	* A '''fan dipole''' (above) consists of multiple dipoles, each cut to a different length for a different band and spaced a few inches from each other. All of the individual dipole elements in the fan dipole share a common feedpoint. This design may be combined with the ''shortened dipole'' by providing loading coil pairs for each individual band. As these antennas can cover multiple bands (such as [[20m]], [[40m]], [[80m]]) using one relatively simple design, these are popular for portable radio-amateur operations such as [[Field Day]].		* A '''fan dipole''' (above) consists of multiple dipoles, each cut to a different length for a different band and spaced a few inches from each other. All of the individual dipole elements in the fan dipole share a common feedpoint. This design may be combined with the ''shortened dipole'' by providing loading coil pairs for each individual band. As these antennas can cover multiple bands (such as [[20m]], [[40m]], [[80m]]) using one relatively simple design, these are popular for portable radio-amateur operations such as [[Field Day]].
	* Many of the most common complex antenna designs, such as [[yagi antenna]]s, [[log-periodic antenna\|log-periodics]], [[panel antenna]]s or [[corner reflector]] antennas, are based on one or more dipoles as driven elements, supplemented by added reflectors or directors to add directionality and gain.		* Many of the most common complex antenna designs, such as [[yagi antenna]]s, [[log-periodic antenna\|log-periodics]], [[panel antenna]]s or [[corner reflector]] antennas, are based on one or more dipoles as driven elements, supplemented by added reflectors or directors to add directionality and gain.

			== See also ==

			* [[Antennas]]
			* [[Gain]]
			* [[SWR]]
			* [[Propagation]]

	== External links ==		== External links ==