Loop antenna - Revision history

Moleski at 16:29, 19 October 2009

2009-10-19T16:29:01Z

← Older revision		Revision as of 16:29, 19 October 2009
Line 1:		Line 1:
	[[Image:Loop antenna.jpg\|thumb\|200px]]		[[Image:Loop antenna.jpg\|thumb\|200px]]
	[[Image:Mantz honolulu antennas.png\|thumb\|200px]]		[[Image:Mantz honolulu antennas.png\|thumb\|200px]]
			[[File:Shoe9.jpg\|thumb\|200px]]
	"A loop antenna has a continuous conducting path leading from one conductor of a two-wire transmission line to the other conductor. All planar loops are directional antennas with a sharp null, and have a radiation pattern similar to the dipole antenna with E and H fields interchanged."<ref>[http://en.wikipedia.org/wiki/Loop_antenna Wikipedia: Loop Antenna]</ref>		"A loop antenna has a continuous conducting path leading from one conductor of a two-wire transmission line to the other conductor. All planar loops are directional antennas with a sharp null, and have a radiation pattern similar to the dipole antenna with E and H fields interchanged."<ref>[http://en.wikipedia.org/wiki/Loop_antenna Wikipedia: Loop Antenna]</ref>

Moleski at 03:33, 13 October 2009

2009-10-13T03:33:04Z

← Older revision		Revision as of 03:33, 13 October 2009
Line 1:		Line 1:
	[[Image:Loop antenna.jpg\|thumb\|200px]]		[[Image:Loop antenna.jpg\|thumb\|200px]]
	[[Image:Mantz honolulu antennas.png\|thumb\|200px]]		[[Image:Mantz honolulu antennas.png\|thumb\|200px]]
	"A loop antenna has a continuous conducting path leading from one conductor of a two-wire transmission line to the other conductor. All planar loops are directional antennas with a sharp null, and have a radiation pattern similar to the dipole antenna with E and H fields interchanged."<ref>[http://en.wikipedia.org/wiki/Loop_antenna] Wikipedia: Loop Antenna</ref>		"A loop antenna has a continuous conducting path leading from one conductor of a two-wire transmission line to the other conductor. All planar loops are directional antennas with a sharp null, and have a radiation pattern similar to the dipole antenna with E and H fields interchanged."<ref>[http://en.wikipedia.org/wiki/Loop_antenna Wikipedia: Loop Antenna]</ref>

	The '''loop antenna''' on the [[Electra]] seems to have been a Bendix MN-5.		The '''loop antenna''' on the [[Electra]] seems to have been a Bendix MN-5.

Moleski at 03:32, 13 October 2009

2009-10-13T03:32:41Z

← Older revision		Revision as of 03:32, 13 October 2009
Line 1:		Line 1:
	[[Image:Loop antenna.jpg\|thumb\|200px]]		[[Image:Loop antenna.jpg\|thumb\|200px]]
	[[Image:Mantz honolulu antennas.png\|thumb\|200px]]		[[Image:Mantz honolulu antennas.png\|thumb\|200px]]
	"A loop antenna has a continuous conducting path leading from one conductor of a two-wire transmission line to the other conductor. All planar loops are directional antennas with a sharp null, and have a radiation pattern similar to the dipole antenna with E and H fields interchanged."<ref>[http://en.wikipedia.org/wiki/Loop_antenna]</ref>		"A loop antenna has a continuous conducting path leading from one conductor of a two-wire transmission line to the other conductor. All planar loops are directional antennas with a sharp null, and have a radiation pattern similar to the dipole antenna with E and H fields interchanged."<ref>[http://en.wikipedia.org/wiki/Loop_antenna] Wikipedia: Loop Antenna</ref>

	The '''loop antenna''' on the [[Electra]] seems to have been a Bendix MN-5.		The '''loop antenna''' on the [[Electra]] seems to have been a Bendix MN-5.

Moleski at 03:32, 13 October 2009

2009-10-13T03:32:14Z

← Older revision		Revision as of 03:32, 13 October 2009
Line 1:		Line 1:
	[[Image:Loop antenna.jpg\|thumb\|200px]]		[[Image:Loop antenna.jpg\|thumb\|200px]]
	[[Image:Mantz honolulu antennas.png\|thumb\|200px]]		[[Image:Mantz honolulu antennas.png\|thumb\|200px]]
	"A loop antenna has a continuous conducting path leading from one conductor of a two-wire transmission line to the other conductor. All planar loops are directional antennas with a sharp null, and have a radiation pattern similar to the dipole antenna with E and H fields interchanged."[http://en.wikipedia.org/wiki/Loop_antenna]		"A loop antenna has a continuous conducting path leading from one conductor of a two-wire transmission line to the other conductor. All planar loops are directional antennas with a sharp null, and have a radiation pattern similar to the dipole antenna with E and H fields interchanged."<ref>[http://en.wikipedia.org/wiki/Loop_antenna]</ref>

	The '''loop antenna''' on the [[Electra]] seems to have been a Bendix MN-5.		The '''loop antenna''' on the [[Electra]] seems to have been a Bendix MN-5.
Line 9:		Line 9:
	== Problems with Earhart's loop antenna ==		== Problems with Earhart's loop antenna ==

	[[Mike Everette]]:<ref>29 January 1999 [http://www.tighar.org/forum/Highlights21_40/highlights21.html Forum.]</ref>		[[Mike Everette]]:<ref>29 January 1999 [http://www.tighar.org/Projects/Earhart/forum/Highlights21_40/highlights21.html Forum.]</ref>

	:A '''loop antenna''' is not a very reliable device in an aircraft at high frequencies. The reason is, that the metal structure and surface of the aircraft creates reflections of the incoming signal -- at ANY frequency -- which can and will create confusion about the exact direction of arrival of the signal. At low frequencies this can be "compensated" for, mechanically and electrically. This compensation consists of distorting the rate of rotation of the loop in certain parts of the compass circle, so that the APPARENT direction as displayed on the bearing indicator gives a more-or-less true heading even though, for instance, there may be a 10-degree error introduced by the wings or tail assembly.		:A '''loop antenna''' is not a very reliable device in an aircraft at high frequencies. The reason is, that the metal structure and surface of the aircraft creates reflections of the incoming signal -- at ANY frequency -- which can and will create confusion about the exact direction of arrival of the signal. At low frequencies this can be "compensated" for, mechanically and electrically. This compensation consists of distorting the rate of rotation of the loop in certain parts of the compass circle, so that the APPARENT direction as displayed on the bearing indicator gives a more-or-less true heading even though, for instance, there may be a 10-degree error introduced by the wings or tail assembly.

Moleski at 14:43, 5 March 2009

2009-03-05T14:43:12Z

← Older revision		Revision as of 14:43, 5 March 2009
Line 1:		Line 1:
	~~{{draft}}~~		[[Image:Loop antenna.jpg\|thumb\|200px]]
	[[Image:Loop antenna.jpg\|thumb\|200px]]"A loop antenna has a continuous conducting path leading from one conductor of a two-wire transmission line to the other conductor. All planar loops are directional antennas with a sharp null, and have a radiation pattern similar to the dipole antenna with E and H fields interchanged."[http://en.wikipedia.org/wiki/Loop_antenna]		[[Image:Mantz honolulu antennas.png\|thumb\|200px]]
			"A loop antenna has a continuous conducting path leading from one conductor of a two-wire transmission line to the other conductor. All planar loops are directional antennas with a sharp null, and have a radiation pattern similar to the dipole antenna with E and H fields interchanged."[http://en.wikipedia.org/wiki/Loop_antenna]

	The '''loop antenna''' on the [[Electra]] seems to have been a Bendix MN-5.		The '''loop antenna''' on the [[Electra]] seems to have been a Bendix MN-5.

Moleski at 15:31, 1 March 2009

2009-03-01T15:31:27Z

← Older revision		Revision as of 15:31, 1 March 2009
Line 27:		Line 27:

	<!-- Please leave this category marker at the bottom. You may add this article to other categories if you wish -->		<!-- Please leave this category marker at the bottom. You may add this article to other categories if you wish -->
	[[Category:Radio considerations]]		[[Category:Radio considerations\|Antenna]]

Moleski at 02:22, 26 February 2009

2009-02-26T02:22:43Z

← Older revision		Revision as of 02:22, 26 February 2009
Line 1:		Line 1:
	{{draft}}		{{draft}}
	"A loop antenna has a continuous conducting path leading from one conductor of a two-wire transmission line to the other conductor. All planar loops are directional antennas with a sharp null, and have a radiation pattern similar to the dipole antenna with E and H fields interchanged."[http://en.wikipedia.org/wiki/Loop_antenna]		[[Image:Loop antenna.jpg\|thumb\|200px]]"A loop antenna has a continuous conducting path leading from one conductor of a two-wire transmission line to the other conductor. All planar loops are directional antennas with a sharp null, and have a radiation pattern similar to the dipole antenna with E and H fields interchanged."[http://en.wikipedia.org/wiki/Loop_antenna]

	The '''loop antenna''' on the [[Electra]] seems to have been a Bendix MN-5.		The '''loop antenna''' on the [[Electra]] seems to have been a Bendix MN-5.

	== Problems with loop ~~antennas~~ ==		Because a loop antenna is highly directional, it is very useful in [[direction finding]].

			== Problems with Earhart's loop antenna ==

	[[Mike Everette]]:<ref>29 January 1999 [http://www.tighar.org/forum/Highlights21_40/highlights21.html Forum.]</ref>		[[Mike Everette]]:<ref>29 January 1999 [http://www.tighar.org/forum/Highlights21_40/highlights21.html Forum.]</ref>

Moleski: New page: {{draft}} "A loop antenna has a continuous conducting path leading from one conductor of a two-wire transmission line to the other conductor. All planar loops are directional antennas with...

2009-02-26T02:13:34Z

New page: {{draft}} "A loop antenna has a continuous conducting path leading from one conductor of a two-wire transmission line to the other conductor. All planar loops are directional antennas with...

New page

{{draft}}
"A loop antenna has a continuous conducting path leading from one conductor of a two-wire transmission line to the other conductor. All planar loops are directional antennas with a sharp null, and have a radiation pattern similar to the dipole antenna with E and H fields interchanged."[http://en.wikipedia.org/wiki/Loop_antenna]

The '''loop antenna''' on the [[Electra]] seems to have been a Bendix MN-5.

== Problems with loop antennas ==

[[Mike Everette]]:<ref>29 January 1999 [http://www.tighar.org/forum/Highlights21_40/highlights21.html Forum.]</ref>

:A '''loop antenna''' is not a very reliable device in an aircraft at high frequencies. The reason is, that the metal structure and surface of the aircraft creates reflections of the incoming signal -- at ANY frequency -- which can and will create confusion about the exact direction of arrival of the signal. At low frequencies this can be "compensated" for, mechanically and electrically. This compensation consists of distorting the rate of rotation of the loop in certain parts of the compass circle, so that the APPARENT direction as displayed on the bearing indicator gives a more-or-less true heading even though, for instance, there may be a 10-degree error introduced by the wings or tail assembly.

:At high frequencies the compensation problem of a loop becomes much more difficult because the actual physical size of the aircraft, in the case of something like a Lockheed 10E or larger, becomes a function of the wavelength of the signal. A quarter-wavelength at 3105 KHz is about 75 feet; at 6210, about 38 feet; at 7500, about 30 feet (rough estimates; I did not take the time to compute actual lengths by formula). The wingspan, the fuselage length, the length of the Vee antenna, all are nearly "resonant lengths" or some fraction thereof at these frequencies. All will create reflections which introduce errors into a loop... MAJOR errors. Given the state of the art in 1937, it does not seem logical to believe that such problems had been solved or at least minimized to a reasonable point... after all, even the LF radio compass was in its infancy, having made the scene in 1935 or so. (Before this, "radio direction finding" in aircraft consisted of fixed loop antennas, so that keeping the aircraft pointed at the station caused a "null" in the pilot's headphones. If the place you needed to fly to was right beside the station, that was fine; but if you needed to find a field located away from the station, there wasn't any way to fly a heading away from it to reach that point, maintaining a reference to the radio station.)

== References ==
<references/>

== Related articles ==

* [[Frequency, wavelength, and antenna tuning]]
* [[Radio equipment on NR16020]]
* [[Direction finding]]
* [[NR16020 antennas]]
* [[Lockheed Electra 10E Special - NR16020]]


[[Category:Radio considerations]]