Dish or Parabola - Revision history

Carlb: /* Links to dish construction projects */

2009-04-09T00:54:46Z

Links to dish construction projects

← Older revision		Revision as of 17:54, 8 April 2009
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	* [http://www.freeantennas.com/projects/template/index.html Deep Dish Cylindrical Parabolic]		* [http://www.freeantennas.com/projects/template/index.html Deep Dish Cylindrical Parabolic]


			{{antennas}}

2008-08-22T21:09:56Z

added related wiki pages

← Older revision		Revision as of 14:09, 22 August 2008
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			Related wiki pages:[[Antennas]], [[Gain]], [[Propagation]], [[SWR]]

	''A number of sources have been used to gain information for this page - including the excellent online microwave antenna book by Peter Wade [http://www.w1ghz.org/10g/10g_home.htm W1GHZ]. The diagrams are original.''		''A number of sources have been used to gain information for this page - including the excellent online microwave antenna book by Peter Wade [http://www.w1ghz.org/10g/10g_home.htm W1GHZ]. The diagrams are original.''

2008-08-22T21:08:06Z

added link heading and link

← Older revision		Revision as of 14:08, 22 August 2008
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			==Links to dish construction projects==

			* [http://www.freeantennas.com/projects/template/index.html Deep Dish Cylindrical Parabolic]

2008-08-12T09:17:17Z

Parabolic Geometry

← Older revision		Revision as of 02:17, 12 August 2008
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	[[Image: Vk4yeh_multi_beam_dish.JPG \| 500px]]		[[Image: Vk4yeh_multi_beam_dish.JPG \| 500px]]

	During receive, the signal is concentrated at the focal point '''F'''. During transmit, a feed point at '''F''' will produce a beam of RF energy.		During receive, the signal is concentrated at the focal point '''F'''. During transmit, energy emmitted at the feed point at '''F''' will produce a beam of RF energy.

	== Finding the focal length of a parabolic dish ==		== Finding the focal length of a parabolic dish ==

2008-08-07T07:21:07Z

fixed link

← Older revision		Revision as of 00:21, 7 August 2008
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	''A number of sources have been used to gain information for this page - including the excellent online microwave antenna book by Peter Wade [http:www.~~qsl~~.~~net~~/~~n1bwt~~/~~preface~~.htm W1GHZ]. The diagrams are original.''		''A number of sources have been used to gain information for this page - including the excellent online microwave antenna book by Peter Wade [http://www.w1ghz.org/10g/10g_home.htm W1GHZ]. The diagrams are original.''

	== Parabolic Geometry ==		== Parabolic Geometry ==

2008-08-07T07:19:18Z

Offset-fed dish antenna

← Older revision		Revision as of 00:19, 7 August 2008
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	== Offset-fed dish antenna ==		== Offset-fed dish antenna ==

	[[Image:~~Vk4yeh_off_centre_dish~~.~~JPG~~ \|~~500px~~]]		Many small dishes are effectively "half' of a parabola. The feedpoint is at the focal point '''F'''

			[[Image:Vk4yeh_offset_dish.jpg\|400px]]

	== Gain of a dish antenna ==		== Gain of a dish antenna ==

2008-08-07T01:22:41Z

← Older revision		Revision as of 18:22, 6 August 2008
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	<math> f = \frac {D^2}{16d} </math> where '''D''' is the diameter of the dish and '''d''' is the depth of the dish		<math> f = \frac {D^2}{16d} </math> where '''D''' is the diameter of the dish and '''d''' is the depth of the dish

	==Gain of a dish antenna==		== Offset-fed dish antenna ==

			[[Image:Vk4yeh_off_centre_dish.JPG \|500px]]

			== Gain of a dish antenna ==

	Related wiki page - [[Gain]]		Related wiki page - [[Gain]]
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	For practical purposes, the most critical measurement affecting the gain (regardless of dish size) of a dish antenna has been found to be placing the feedpoint exactly at the focal length '''f'''. Paul Wade - [http://www.qsl.net/n1bwt/preface.htm W1GHZ], gives the following relative gain measurements for a 22inch dish with <math> \frac{f}{D} =0.39 </math> operating at 10GHz:		For practical purposes, the most critical measurement affecting the gain (regardless of dish size) of a dish antenna has been found to be placing the feedpoint exactly at the focal length '''f'''. Paul Wade - [http://www.qsl.net/n1bwt/preface.htm W1GHZ], gives the following relative gain measurements for a 22inch dish with <math> \frac{f}{D} =0.39 </math> operating at 10GHz:

	{\| style="width:55" border = "1"		{\| style="width:55" border = "1"
	\| Feed distance \|\| Relative gain		\| Feed distance \|\| Relative gain
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	~~==Offset Fed dish antennas==~~

	~~[[Image:Vk4yeh_off_centre_dish.JPG \|500px]]~~

2008-08-07T01:12:02Z

added off-set dish diagram

← Older revision		Revision as of 18:12, 6 August 2008
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	==Offset Fed dish antennas==		==Offset Fed dish antennas==

			[[Image:Vk4yeh_off_centre_dish.JPG \|500px]]

2008-08-06T22:49:48Z

← Older revision		Revision as of 15:49, 6 August 2008
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			''A number of sources have been used to gain information for this page - including the excellent online microwave antenna book by Peter Wade [http:www.qsl.net/n1bwt/preface.htm W1GHZ]. The diagrams are original.''

	== Parabolic Geometry ==		== Parabolic Geometry ==

2008-08-06T22:35:50Z