Amateur Radio Wiki - User contributions [en]

Talk:Oh no oh no oh no oh no oh no oh no oh no oh no oh no oh no oh no oh no oh no oh no oh no oh no oh no oh no oh no oh no oh no oh no oh no oh no oh no oh no oh no oh no oh no oh no oh no oh no oh no oh no oh no oh no oh no oh no oh no oh no oh no oh no oh

2017-08-05T08:28:39Z

G4juv: /* Is this Wiki being maintained? */

== Why a (separate) forum? ==

Why is there a separate forum for this wiki? Seems to me mediawiki has all we need with discussion pages (as we could prove here :). If we want to have general discussions, we could have a [[Project:Forum]] page that would indicate the idea of the forum and a [[Project_talk:Forum]] page that would be the chat itself...

It seems to me the SMF forum just adds extra burden to the administration of this site. For example, there's spam now in the forum too, and very little content.. Why not focus our energies here? -- [[User:TheAnarcat|TheAnarcat]] 17:24, 2 October 2010 (CDT)

:I have found the old [[Discussions]] page, and I moved it to [[Project:Forum]]... It was fairly confusing since that page was targeted at being a temporary measure while the forum was created, but then it was included in the "websites" template... so i removed it from the template, and moved it within the project pages, where it belongs. -- [[User:TheAnarcat|TheAnarcat]] 11:54, 3 October 2010 (CDT)
:In fact that [[Discussions]] page was created *after* the forum and was explaining how the forum was needed "sorting out". So I assume the forum situation is not ideal, and that we can get rid of it. I have therefore edited the frontpage to point to the wiki forum instead of the separate wiki. -- [[User:TheAnarcat|TheAnarcat]] 12:00, 3 October 2010 (CDT)

== Let's cleanup the frontpage ==

The frontpage isn't really pretty right now. While there's a lot of good information in this wiki, the frontpage doesn't allow for easily finding it. We should focus on guiding incoming users based on what they are looking for or who they are. A "newbies" section would be really good. I think we could be inspired by the [http://amateurradiowiki.us/wiki/index.php?title=Main_Page frontpage of the amateurradiowiki.us site]: even though that site has less [http://amateurradiowiki.us/wiki/index.php?title=Special:AllPages pages] and [http://amateurradiowiki.us/wiki/index.php?title=Special:Statistics visits], it's better organised in some places... Oh and it copies a lot of content straight from wikipedia... --[[User:TheAnarcat|TheAnarcat]] 19:05, 2 October 2010 (CDT)

:I have created an alternative frontpage, see [[Project:New frontpage proposal]]. If there are no objections within a week, I will put it online. --[[User:TheAnarcat|TheAnarcat]] 11:29, 3 October 2010 (CDT)

::I have put the new frontpage online. -- [[User:TheAnarcat|TheAnarcat]] 23:28, 10 October 2010 (CDT)

== How does this compare to wikipedia? ==

My last question is this: how does this compare to [http://en.wikipedia.org/wiki/Wikipedia:WikiProject_Amateur_radio wikipedia's ham radio project]? It seems there are a lot of good quality articles on wikipedia (especially the band plans, where the articles are just better than what's here), so I'm not sure where the boundary should lie between the two wiki... See also the [http://toolserver.org/~tim1357/cgi-bin/wikiproject_watchlist.py?cat=0&template=WikiProject+Amateur+radio&limit=25&user=&order=desc recent changes of that portal]. -- [[User:TheAnarcat|TheAnarcat]] 22:14, 2 October 2010 (CDT)

: I think I have a good answer now: here is the "how", wikipedia is the "what". We also take refugees and content too specific to fit into wikipedia. Documented this in [[Project:Posting guidelines]]. I also posted [http://en.wikipedia.org/wiki/Wikipedia_talk:WikiProject_Amateur_radio#How_about_that_amateur-radio-wiki.net.3F this note on wikipedia]. --[[User:TheAnarcat|TheAnarcat]] 14:04, 3 October 2010 (CDT)

== Is this Wiki being maintained? ==

There seem to be a few problems. Image links in my [[Gate_Spring_Dipole]] page have stopped working but the files are present in the gallery. I was planning to upload another article but I'll wait until things are working again. I'm guessing that a wiki upgrade has broken the code that handles image thumbnails. Or it could be file permissions on the image directory structure. I gave up managing my own Mediawiki site due to problems like this. Thanks in advance for the hoped for fix. --[[User:G4juv|G4juv]] ([[User talk:G4juv|talk]]) 01:21, 5 August 2017 (PDT)

Wellbrook loop plus Spiderbeam fibreglass pole

2017-08-05T08:27:53Z

G4juv: /* Portable_antenna */

[[File:Spiderbeam Pole Plus Wellbrook Loop.jpg]]

[[Category:Portable_antenna]]

File:Spiderbeam Pole Plus Wellbrook Loop.jpg

2017-08-05T08:27:17Z

G4juv: Category:Portable_antenna

[[Category:Portable_antenna]]

Category:Portable antenna

2017-08-05T08:26:31Z

G4juv: /* Portable_antenna */

This category if for pages and images related to portable antennas.

User:G4juv

2017-08-05T08:23:47Z

G4juv: /* A portable antenna */

== G4JUV ==

Neil is located in Bungak, Suffolk, UK.

=== Neil's Wiki Articles ===

* [[Gate Spring Dipole]]
* [[Wellbrook loop plus Spiderbeam fibreglass pole]]

User talk:G4juv

2017-08-05T08:22:11Z

G4juv: /* Deafening silence */

No one want to talk to me :(

Talk:Oh no oh no oh no oh no oh no oh no oh no oh no oh no oh no oh no oh no oh no oh no oh no oh no oh no oh no oh no oh no oh no oh no oh no oh no oh no oh no oh no oh no oh no oh no oh no oh no oh no oh no oh no oh no oh no oh no oh no oh no oh no oh no oh

2017-08-05T08:21:07Z

G4juv: /* Is this Wiki being maintained? */ new section

== Why a (separate) forum? ==

Why is there a separate forum for this wiki? Seems to me mediawiki has all we need with discussion pages (as we could prove here :). If we want to have general discussions, we could have a [[Project:Forum]] page that would indicate the idea of the forum and a [[Project_talk:Forum]] page that would be the chat itself...

It seems to me the SMF forum just adds extra burden to the administration of this site. For example, there's spam now in the forum too, and very little content.. Why not focus our energies here? -- [[User:TheAnarcat|TheAnarcat]] 17:24, 2 October 2010 (CDT)

:I have found the old [[Discussions]] page, and I moved it to [[Project:Forum]]... It was fairly confusing since that page was targeted at being a temporary measure while the forum was created, but then it was included in the "websites" template... so i removed it from the template, and moved it within the project pages, where it belongs. -- [[User:TheAnarcat|TheAnarcat]] 11:54, 3 October 2010 (CDT)
:In fact that [[Discussions]] page was created *after* the forum and was explaining how the forum was needed "sorting out". So I assume the forum situation is not ideal, and that we can get rid of it. I have therefore edited the frontpage to point to the wiki forum instead of the separate wiki. -- [[User:TheAnarcat|TheAnarcat]] 12:00, 3 October 2010 (CDT)

== Let's cleanup the frontpage ==

The frontpage isn't really pretty right now. While there's a lot of good information in this wiki, the frontpage doesn't allow for easily finding it. We should focus on guiding incoming users based on what they are looking for or who they are. A "newbies" section would be really good. I think we could be inspired by the [http://amateurradiowiki.us/wiki/index.php?title=Main_Page frontpage of the amateurradiowiki.us site]: even though that site has less [http://amateurradiowiki.us/wiki/index.php?title=Special:AllPages pages] and [http://amateurradiowiki.us/wiki/index.php?title=Special:Statistics visits], it's better organised in some places... Oh and it copies a lot of content straight from wikipedia... --[[User:TheAnarcat|TheAnarcat]] 19:05, 2 October 2010 (CDT)

:I have created an alternative frontpage, see [[Project:New frontpage proposal]]. If there are no objections within a week, I will put it online. --[[User:TheAnarcat|TheAnarcat]] 11:29, 3 October 2010 (CDT)

::I have put the new frontpage online. -- [[User:TheAnarcat|TheAnarcat]] 23:28, 10 October 2010 (CDT)

== How does this compare to wikipedia? ==

My last question is this: how does this compare to [http://en.wikipedia.org/wiki/Wikipedia:WikiProject_Amateur_radio wikipedia's ham radio project]? It seems there are a lot of good quality articles on wikipedia (especially the band plans, where the articles are just better than what's here), so I'm not sure where the boundary should lie between the two wiki... See also the [http://toolserver.org/~tim1357/cgi-bin/wikiproject_watchlist.py?cat=0&template=WikiProject+Amateur+radio&limit=25&user=&order=desc recent changes of that portal]. -- [[User:TheAnarcat|TheAnarcat]] 22:14, 2 October 2010 (CDT)

: I think I have a good answer now: here is the "how", wikipedia is the "what". We also take refugees and content too specific to fit into wikipedia. Documented this in [[Project:Posting guidelines]]. I also posted [http://en.wikipedia.org/wiki/Wikipedia_talk:WikiProject_Amateur_radio#How_about_that_amateur-radio-wiki.net.3F this note on wikipedia]. --[[User:TheAnarcat|TheAnarcat]] 14:04, 3 October 2010 (CDT)

== Is this Wiki being maintained? ==

There seem to be a few problems. Image links in my [[Gate_Spring_Dipole]] page have stopped working but the files are present in the gallery. I was planning to upload another article but I'll wait until things are working again. I'm guessing that a wiki upgrade has broken the code that handles image thumbnails. I gave up managing my own Mediawiki site due to problems like this. Thanks in advance for the hoped for fix. --[[User:G4juv|G4juv]] ([[User talk:G4juv|talk]]) 01:21, 5 August 2017 (PDT)

Category:Optical Communication

2014-06-26T12:51:31Z

G4juv: /* A new category for optical communications */

A category for articles on communication using infra-red or visible light as the carrier.

Small tuned loop

2012-01-30T11:31:08Z

G4juv:

[[File:Small-Loop-Antenna-G4JUV.gif|right]] A '''small transmitting loop''', '''small tuned loop''' or '''magnetic antenna''' is defined as a [[loop antenna]] of less than one-tenth to one-quarter of a wavelength in circumference. These are normally constructed as a single turn of heavy-gauge wire (AWG #10 or larger), copper pipe or tubing and are tuned to one specific frequency at a time using a series variable [[capacitor]].

As these antennas can be constructed in relatively little space, often with diameter of several feet or less, they are used in [[HF]] applications where no suitable location is available for a full-sized antenna such as the [[beam antenna]]. In some cases, these have been constructed in attics or used for [[portable antenna|portable]] operation.[http://www.laud.no/la6nca/loop/]

While a circular loop is efficient in that it provides the largest area for any one given length of conductor, other form factors (such as a square formed from copper pipe and 90° elbows) have also been successfully employed.

== Theory of operation ==
A wire loop inherently acts as an [[inductor]] with a radiation resistance of a fraction of an ohm. In order to keep other [[resistance]] and [[impedance]]s from becoming predominant, the resistance must be kept to a minimum in transmitting antennas by the use of heavy wire or tubing and the inductance of the loop must be compensated using a large series capacitor.

This yields an antenna which operates as a resonant [[LC circuit]] at one specific frequency with an impedance very close to zero; at other frequencies, impedance rises sharply and the antenna is unresponsive.

== Tuning ==
Due to the need to maintain low impedance, capacitors used must have effective series resistance of near-zero, despite their handling of large amounts of current and RF voltages which (in any larger than a QRP operation) often reach 4kV or more. As the circuit is largely built from reactive elements, voltages and currents at individual points far exceed those which normally would be associated with the real power being transmitted. The capacitors must also be variable over a wide range to allow the loop to be manually tuned to one of various frequencies and bands in the HF spectrum.

Vacuum variable capacitors are very well suited to this task, but may be costly even from industrial-surplus sources. A possible alternative is an air-variable capacitor in which all connections to individual plates are welded and there are no moving connections to the rotor. The ''butterfly capacitor'' ([http://www.mfjenterprises.com/Product.php?productid=MFJ-19 MFJ-19], [http://www.mfjenterprises.com/Product.php?productid=MFJ-23 MFJ-23]) is a split-stator capacitor based on this approach; an air-variable design, it effectively has two stators (one connected to each end of the loop) and a rotor which moves between them to adjust capacitance. No direct electrical connection is wired to the rotor; there are no brushes or slip rings.

Some radioamateurs have constructed their own capacitors for use in tuned loop antennas; these are usually air-variable capacitors built from individually-machined plates or trombone capacitors in which two concentric pieces of copper pipe are separated by an insulator and one slides into the other to vary the capacitance.

As the circuit is very frequency-selective, often a means is desired to remotely adjust capacitance to tune the antenna to the desired channel frequency. Reduction drives may be used to convert a single-turn variable capacitor to more finely-tunable multiturn control and motors (such as steppers designed for computer printers or servos used in radio-control operation) may provide a means to tune the antenna remotely.

== Feedpoint matching ==
As the impedance of the small loop antenna at resonance is near-zero, it must be matched to the higher impedance (typically 50Ω) of the transmitting equipment.

Possible methods to match transmitter to loop are:
* Matching loop - A second loop, typically no more than one-fifth the size of the main loop, is constructed and installed adjacent to one edge of the main loop and used to couple the signal inductively.[http://www.qsl.net/ea5xq/ea5xqpre_magneticloop.html]
* Delta match - One small portion of the loop is used as an [[autotransformer]] by connecting two taps to one portion of the loop circumference, usually at the point most distant from the capacitor. These are then connected using balanced line (two conductors of equal length and size) to a [[balun]] or matching device and fed as a balanced load.
* Army match - The transmitter is matched to the antenna capacitively
* Gamma match - The shield of an unbalanced line is connected directly to the circumference of the loop at a point directly opposite the tuning capacitor. The centre conductor is then installed, unshielded, at a 1" spacing from the loop and hard-wired to the loop at a more distant point - effectively forming an unbalanced matching loop which includes part of the main loop as one side of the feed loop.[http://www.qsl.net/dl7jv/e.mag.htm]

== External links ==
* [http://www.qsl.net/we6w/projects/160_loop.txt 160m Short TX Loop] antenna, WE6W
* [http://web.telia.com/~u85920178/antennas/frameant.htm 80 metre Frame Antenna] and [http://web.telia.com/~u85920178/antennas/servo.htm Remote Antenna Tuner], Harry Lythall - SM0VPO
* [http://frrl.wordpress.com/2009/03/21/limited-space-antennas-the-small-transmitting-loop-antenna/ The AEA Isoloop]
* [http://qrpfr.free.fr/?2006/04/14/20-antenne-cadre-par-f5ngz Antenne Cadre] par F5NGZ + Description F5TZ, QRP FR (en français)
* [http://www.qsl.net/dj3tz/loop2.html DJ3TZ's Small Tuned Loop Antenna] Page
* [http://www.davesergeant.com/loops.htm Experiences with Loop antennas] at G3YMC
* [http://www.qsl.net/hb9mtn/hb9mtn_magnet_80.html Magnetic Loop for 80m - 40m], HB9MTN
* [http://www.qsl.net/g4fon/MagLoop.htm Magnetic Loop Antenna], G4FON
* [http://www.laud.no/la6nca/loop/ Magnetic Loop Antenna], LA6NCA Larvik, Norway
* [http://www.qsl.net/mnqrp/Loop/Mag_Loops.htm Magnetic Loop Antennas], Tony Van Herck ON4CEQ
* [http://home.alphalink.com.au/~parkerp/gateway/nodec97.htm A magnetic loop antenna for HF], Peter Parker VK3YE
* [http://www.kr1st.com/magloop.htm My Magnetic Loop Antenna], KR1ST - a small transmitting loop
* See also [http://www.kr1st.com/swlloop.htm A small receiving loop with a good frequency range]
* [http://www.geocities.com/gw0tqm/magloop/magloop.htm The Myth and Mystery of the Magnetic Loop], GW0TQM
* [http://homepages.ipact.nl/~geurink/magneticloop/ PA3CQR Magnetic loop antenna]
* [http://dt.prohosting.com/hacks/antenna/magloop.html Portable HF Transmitting Loop Antenna], N5IZU
* [http://www.qsl.net/pa3hbb/magloop2.htm Practical Experiments with Magnetic Loop antennas], David Reid PA3HBB / G0BZF
* [http://users.tpg.com.au/users/ldbutler/HFTXLoop.htm A Small Transmitting Loop Antenna for 14MHz and 21MHz], Lloyd Butler VK5BR, Amateur Radio, November 1991.
* [http://www.aa5tb.com/loop.html Small Transmitting Loop Antennas], AA5TB (includes aa5tb_loop_v1.22a.xls small loop spreadsheet calculator)
* [http://www.g4ilo.com/stealth.html Stealth Amateur Radio], G4ILO
* [http://www.qsl.net/ok1fou/e_loop10.html An Unusual Two Band Magnetic Loop Antenna] (for 14 and 10 MHz), OK1FOU
* [http://www.standpipe.com/w2bri/article1.htm W2BRI's Magnetic Loops]

{{antennas}}

File:Small-Loop-Antenna-G4JUV.gif

2012-01-30T11:28:53Z

G4juv: Category:Antennas

[[Category:Antennas]]

Loop antenna

2012-01-30T11:15:30Z

G4juv:

There are two types of loop antennas: '''small loops''' and '''large loops'''. The key difference between the two is that in a small loop, the current is approximately in phase at all points around the loop, while in a large loops the phase varies at different points. The two types of antenna have very different properties and are used for different purposes.

== Small Loops ==

''Main article: [[small tuned loop]]''

A common saying in antenna design circles is "small, efficient, [[broadband]]: pick any two". As their name implies, small loops are small and reasonably efficient, but they are necessarily narrowband antennas. This means that even small changes in frequency require retuning the antenna.

[[Mobile antenna|Short linear antennas]], whether horizontal or vertical, have capacitive reactance and require an inductor for tuning. [[Small tuned loop|small loops]] are just they opposite; they have significant inductive reactance, and require a capacitor for tuning. Most [[Small tuned loop|small loops]] use a variable capacitor, allowing the antenna to be tuned over a wide range (5 MHz - 15 MHz is easily accomplished).

Small loop antennas have a perimeter of no more than 0.12 λ. (Remember that λ is the symbol for [[Electromagnetic Waves|wavelength]].) They are normally mounted in the vertical plane.

This type of antenna has very sharp [[nulls]] at right angles to the plane of the loop. These nulls can be very useful for suppressing [[QRM]] from a local source. Simply rotate the loop until the interference can no longer be heard. Because the [[nulls]] are sharp, small changes in antenna orientation can make a large change in signal or noise received from the direction of the [[nulls]]. The [[nulls]] are sharpest on the smallest loops (perimeter approximately 0.05 λ, and gradually broaden as the perimeter increases to 0.1 λ and beyond.

== Large Loops ==

Large loop antennas have a perimeter of at least 1/2 λ, but they develop significant gain when increased to 1 λ or 2 λ. Large loops are normally mounted in the horizontal plane.

'''Need to insert diagram of large horizontal loop fed by ladder-line'''

== Quads ==

[[Quad antenna|Quad antennas]] are essential multiple large loops mounted near each other, with one of them fed and the others used as [[passive elements]]. [[Quad antenna|Quads]] can achieve significant [[gain]]. They have more theoretical gain than the commonly used [[yagi|yagis]], but they're harder to build since they require significantly more room and are a bit more sensitive so many people just opt for building [[yagi|yagis]] instead.

{{antennas}}

Impedance matching

2012-01-30T11:10:55Z

G4juv:

Impedance Matching is required to '''maximise energy transfer''' from an AC source to a device.

Examples:
* Transform 240V AC to 12V AC for a power supply.
* Transform a 7 Kohm audio source (from an amplifier for instance) down to 16 Ohms for a headphone or loudspeaker.
- both of these can be done by using a transformer.

* Couple an antenna with impedance other than 50 Ohm and non-zero reactance to a transceiver with 50 Ohm purely reactive impedance.
This is done by an ATU. The simplest form of an ATU consists of a variable capacitor between TRTX and ground followed by a series variable inductor, which in turn is followed by a series variable capacitor which leads to the antenna (in case of an unbalanced feed line).

[[File:ATU.jpg]]

{{antennas}}

Gate Spring Dipole

2012-01-30T11:04:45Z

G4juv: /* External Links */

== A Shrunken Dipole with Loading Coils ==

[[User:G4juv|Neil]] built this dipole which uses farm gate springs as loading coils. You can get an 80 metre dipole into quite a small space. Of course you lose efficiency but this is for people with less than 40 metres of back garden.

[[File:Gate-spring-dipole.GIF]]

Visit your local farm supplies store or go on-line and buy two kits like this. Get stainless steel if you can.

[[File:Gate-spring-kit.JPG]]

Make the dipole using the longest wire length that will fit your limited space. Mount it as high as possible. Mine is set up as an inverted V.

Use an ATU to tune it up and you are done. If you have an antenna analyser, it should be possible to optimise the antenna by tweaking the wire lengths and the amount of stretch in the loading coils. This should result in a more efficient antenna.

[[File:G4JUV-Gate-Spring-Dipole-01.jpg]]

[[File:G4JUV-Gate-Spring-Dipole-02.jpg]]

== More Details ==

This is an 80 metre dipole that fits in a small space. An ATU is needed and using the ATU, the antenna works on other bands too. It is ideal for portable use because of its small size.

This antenna idea came from various websites where the metal slinky toy had been pressed into use for an antenna. The slinky suffers from corrosion and is really only suitable for indoor use.

What was needed was an outdoor, heavy duty, corrosion resistant slinky. The electric fence gate spring fitted the bill. Get ones that stretch up to 5 metres. They are available on line too.

Discard everything apart from the springs. Now build your dipole. The wire should be as long as your available space permits. I used about 5 metres on each leg.

The spring need not be stretched far but make sure the turns are not touching, even in strong wind.

My gate spring could not be soldered so the wires were attached with screw down chocolate blocks, well greased with silicone to slow corrosion at the contact points.

My antenna was mounted as an inverted vee with the ends about 2.5 metres above ground.
The centre feed was about 6 metres above the ground.
This configuration is likely to have a high radiation angle, good for more local contacts.
For a lower radiation angle, mount it vertically or as near to vertical as possible. An inverted L might also work but both these configurations might have more unbalanced feeder currents.

Using an antenna tuning unit suitable for balanced line, this could be brought to 1:1 SWR on 80, 40 and 20 metres but not 160 metres.
Using four springs might work for top band. "Fourspring Durch Technik"!

Within minutes, I had QSOs from the UK to Italy and the Channel Islands so the antenna works. Obviously a full size dipole will work better but this is a nice idea for a site with limited space. This whole exercise was done on guesswork. If I ever have time, I might use an antenna analyser to see if the design could be improved. Proper resonance on 80 metres would be a good start.

To make the antenna work better, experiment with the amount of spring stretch and the length of the wire sections.

I plan to raise the entire antenna using three poles, two at the ends and one in the centre. This should reduce losses, raise the feed impedance and improve the efficiency of the antenna. There is space for a longer antenna. This one was cut to length using all my available wire.

I have seen articles that recommend the loading coil goes in the middle of the wire stretch or at the feed point. I attended a lecture by an antenna specialist who made it clear that the high current parts of the antenna should be as large as possible so putting the loading coil at the feed point might tune correctly but will be less efficient.

== External Links ==

*[http://www.radiowymsey.org/FanDipole/slinky.htm M0WYM Slinky Dipole]
*[http://www.nonstopsystems.com/radio/frank_radio_antenna.htm N4SPP Slinky Dipole]
*[http://www.eham.net/articles/23260 N1FDX Slinky Dipole]

== G4JUV ==

User [[User:G4juv|Neil]] wrote this.

{{antennas}}

Gate Spring Dipole

2011-05-15T05:29:38Z

G4juv:

== A Shrunken Dipole with Loading Coils ==

[[User:G4juv|Neil]] built this dipole which uses farm gate springs as loading coils. You can get an 80 metre dipole into quite a small space. Of course you lose efficiency but this is for people with less than 40 metres of back garden.

[[File:Gate-spring-dipole.GIF]]

Visit your local farm supplies store or go on-line and buy two kits like this. Get stainless steel if you can.

[[File:Gate-spring-kit.JPG]]

Make the dipole using the longest wire length that will fit your limited space. Mount it as high as possible. Mine is set up as an inverted V.

Use an ATU to tune it up and you are done. If you have an antenna analyser, it should be possible to optimise the antenna by tweaking the wire lengths and the amount of stretch in the loading coils. This should result in a more efficient antenna.

[[File:G4JUV-Gate-Spring-Dipole-01.jpg]]

[[File:G4JUV-Gate-Spring-Dipole-02.jpg]]

== More Details ==

This is an 80 metre dipole that fits in a small space. An ATU is needed and using the ATU, the antenna works on other bands too. It is ideal for portable use because of its small size.

This antenna idea came from various websites where the metal slinky toy had been pressed into use for an antenna. The slinky suffers from corrosion and is really only suitable for indoor use.

What was needed was an outdoor, heavy duty, corrosion resistant slinky. The electric fence gate spring fitted the bill. Get ones that stretch up to 5 metres. They are available on line too.

Discard everything apart from the springs. Now build your dipole. The wire should be as long as your available space permits. I used about 5 metres on each leg.

The spring need not be stretched far but make sure the turns are not touching, even in strong wind.

My gate spring could not be soldered so the wires were attached with screw down chocolate blocks, well greased with silicone to slow corrosion at the contact points.

My antenna was mounted as an inverted vee with the ends about 2.5 metres above ground.
The centre feed was about 6 metres above the ground.
This configuration is likely to have a high radiation angle, good for more local contacts.
For a lower radiation angle, mount it vertically or as near to vertical as possible. An inverted L might also work but both these configurations might have more unbalanced feeder currents.

Using an antenna tuning unit suitable for balanced line, this could be brought to 1:1 SWR on 80, 40 and 20 metres but not 160 metres.
Using four springs might work for top band. "Fourspring Durch Technik"!

Within minutes, I had QSOs from the UK to Italy and the Channel Islands so the antenna works. Obviously a full size dipole will work better but this is a nice idea for a site with limited space. This whole exercise was done on guesswork. If I ever have time, I might use an antenna analyser to see if the design could be improved. Proper resonance on 80 metres would be a good start.

To make the antenna work better, experiment with the amount of spring stretch and the length of the wire sections.

I plan to raise the entire antenna using three poles, two at the ends and one in the centre. This should reduce losses, raise the feed impedance and improve the efficiency of the antenna. There is space for a longer antenna. This one was cut to length using all my available wire.

I have seen articles that recommend the loading coil goes in the middle of the wire stretch or at the feed point. I attended a lecture by an antenna specialist who made it clear that the high current parts of the antenna should be as large as possible so putting the loading coil at the feed point might tune correctly but will be less efficient.

== External Links ==

*[http://www.radiowymsey.org/FanDipole/slinky.htm M0WYM Slinky Dipole]
*[http://www.nonstopsystems.com/radio/frank_radio_antenna.htm N4SPP Slinky Dipole]
*[http://www.eham.net/articles/23260 N1FDX Slinky Dipole]
*[http://www.ki6yfq.com/projects/slinky_dipole_antenna.html KI6YFQ Slinky Dipole]

== G4JUV ==

User [[User:G4juv|Neil]] wrote this.

{{antennas}}

Gate Spring Dipole

2011-05-12T13:28:01Z

G4juv:

== A Shrunken Dipole with Loading Coils ==

[[User:G4juv|Neil]] built this dipole which uses farm gate springs as loading coils. You can get an 80 metre dipole into quite a small space. Of course you lose efficiency but this is for people with less than 40 metres of back garden.

[[File:Gate-spring-dipole.GIF]]

Visit your local farm supplies store or go on-line and buy two kits like this. Get stainless steel if you can.

[[File:Gate-spring-kit.JPG]]

Make the dipole using the longest wire length that will fit your limited space. Mount it as high as possible. Mine is set up as an inverted V.

Use an ATU to tune it up and you are done. If you have an antenna analyser, it should be possible to optimise the antenna by tweaking the wire lengths and the amount of stretch in the loading coils. This should result in a more efficient antenna.

[[File:G4JUV-Gate-Spring-Dipole-01.jpg]]

[[File:G4JUV-Gate-Spring-Dipole-02.jpg]]

== More Details ==

This is an 80 metre dipole that fits in a small space. An ATU is needed and using the ATU, the antenna works on other bands too. It is ideal for portable use because of its small size.

This antenna idea came from various websites where the metal slinky toy had been pressed into use for an antenna. The slinky suffers from corrosion and is really only suitable for indoor use.

What was needed was an outdoor, heavy duty, corrosion resistant slinky. The electric fence gate spring fitted the bill. Get ones that stretch up to 5 metres. They are available on line too.

Discard everything apart from the springs. Now build your dipole. The wire should be as long as your available space permits. I used about 5 metres on each leg.

The spring need not be stretched far but make sure the turns are not touching, even in strong wind.

My gate spring could not be soldered so the wires were attached with screw down chocolate blocks, well greased with silicone to slow corrosion at the contact points.

My antenna was mounted as an inverted vee with the ends about 2.5 metres above ground.
The centre feed was about 6 metres above the ground.
This configuration is likely to have a high radiation angle, good for more local contacts.
For a lower radiation angle, mount it vertically or as near to vertical as possible. An inverted L might also work but both these configurations might have more unbalanced feeder currents.

Using an antenna tuning unit suitable for balanced line, this could be brought to 1:1 SWR on 80, 40 and 20 metres but not 160 metres.
Using four springs might work for top band. "Fourspring Durch Technik"!

Within minutes, I had QSOs from the UK to Italy and the Channel Islands so the antenna works. Obviously a full size dipole will work better but this is a nice idea for a site with limited space. This whole exercise was done on guesswork. If I ever have time, I might use an antenna analyser to see if the design could be improved. Proper resonance on 80 metres would be a good start.

To make the antenna work better, experiment with the amount of spring stretch and the length of the wire sections.

I plan to raise the entire antenna using three poles, two at the ends and one in the centre. This should reduce losses, raise the feed impedance and improve the efficiency of the antenna. There is space for a longer antenna. This one was cut to length using all my available wire.

I have seen articles that recommend the loading coil goes in the middle of the wire stretch or at the feed point. I attended a lecture by an antenna specialist who made it clear that the high current parts of the antenna should be as large as possible so putting the loading coil at the feed point might tune correctly but will be less efficient.

== External Links ==

*[http://www.radiowymsey.org/FanDipole/slinky.htm M0WYM Slinky Dipole]
*[http://www.nonstopsystems.com/radio/frank_radio_antenna.htm N4SPP Slinky Dipole]
*[http://www.eham.net/articles/23260 N1FDX Slinky Dipole]
*[http://www.ki6yfq.com/projects/slinky_dipole_antenna.html KI6YFQ Slinky Dipole]

{{antennas}}

User:G4juv

2011-05-12T13:11:25Z

G4juv:

== G4JUV ==

Neil is located in Beccles, Suffolk, UK.

=== Neil's Wiki Articles ===

[[Gate Spring Dipole]]

Gate Spring Dipole

2011-05-12T13:10:56Z

G4juv:

[[User:G4juv|Neil]] built this dipole which uses farm gate springs as loading coils. You can get an 80 metre dipole into quite a small space. Of course you lose efficiency but this is for people with less than 40 metres of back garden.

[[File:Gate-spring-dipole.GIF]]

Visit your local farm supplies store or go on-line and buy two kits like this. Get stainless steel if you can.

[[File:Gate-spring-kit.JPG]]

Make the dipole using the longest wire length that will fit your limited space. Mount it as high as possible. Mine is set up as an inverted V.

Use an ATU to tune it up and you are done. If you have an antenna analyser, it should be possible to optimise the antenna by tweaking the wire lengths and the amount of stretch in the loading coils. This should result in a more efficient antenna.

[[File:G4JUV-Gate-Spring-Dipole-01.jpg]]

[[File:G4JUV-Gate-Spring-Dipole-02.jpg]]

== More Details ==

This is an 80 metre dipole that fits in a small space. An ATU is needed and using the ATU, the antenna works on other bands too. It is ideal for portable use because of its small size.

This antenna idea came from various websites where the metal slinky toy had been pressed into use for an antenna. The slinky suffers from corrosion and is really only suitable for indoor use.

What was needed was an outdoor, heavy duty, corrosion resistant slinky. The electric fence gate spring fitted the bill. Get ones that stretch up to 5 metres. They are available on line too.

Discard everything apart from the springs. Now build your dipole. The wire should be as long as your available space permits. I used about 5 metres on each leg.

The spring need not be stretched far but make sure the turns are not touching, even in strong wind.

My gate spring could not be soldered so the wires were attached with screw down chocolate blocks, well greased with silicone to slow corrosion at the contact points.

My antenna was mounted as an inverted vee with the ends about 2.5 metres above ground.
The centre feed was about 6 metres above the ground.
This configuration is likely to have a high radiation angle, good for more local contacts.
For a lower radiation angle, mount it vertically or as near to vertical as possible. An inverted L might also work but both these configurations might have more unbalanced feeder currents.

Using an antenna tuning unit suitable for balanced line, this could be brought to 1:1 SWR on 80, 40 and 20 metres but not 160 metres.
Using four springs might work for top band. "Fourspring Durch Technik"!

Within minutes, I had QSOs from the UK to Italy and the Channel Islands so the antenna works. Obviously a full size dipole will work better but this is a nice idea for a site with limited space. This whole exercise was done on guesswork. If I ever have time, I might use an antenna analyser to see if the design could be improved. Proper resonance on 80 metres would be a good start.

To make the antenna work better, experiment with the amount of spring stretch and the length of the wire sections.

I plan to raise the entire antenna using three poles, two at the ends and one in the centre. This should reduce losses, raise the feed impedance and improve the efficiency of the antenna. There is space for a longer antenna. This one was cut to length using all my available wire.

I have seen articles that recommend the loading coil goes in the middle of the wire stretch or at the feed point. I attended a lecture by an antenna specialist who made it clear that the high current parts of the antenna should be as large as possible so putting the loading coil at the feed point might tune correctly but will be less efficient.

{{antennas}}

Gate Spring Dipole

2011-05-12T12:58:48Z

G4juv:

This is a dipole which uses farm gate springs as loading coils. You can get an 80 metre dipole into quite a small space. Of course you lose efficiency but this is for people with less than 40 metres of back garden.

[[File:Gate-spring-dipole.GIF]]

Visit your local farm supplies store or go on-line and buy two kits like this. Get stainless steel if you can.

[[File:Gate-spring-kit.JPG]]

Make the dipole using the longest wire length that will fit your limited space. Mount it as high as possible. Mine is set up as an inverted V.

Use an ATU to tune it up and you are done. If you have an antenna analyser, it should be possible to optimise the antenna by tweaking the wire lengths and the amount of stretch in the loading coils. This should result in a more efficient antenna.

[[File:G4JUV-Gate-Spring-Dipole-01.jpg]]

[[File:G4JUV-Gate-Spring-Dipole-02.jpg]]

== More Details ==

This is an 80 metre dipole that fits in a small space. An ATU is needed and using the ATU, the antenna works on other bands too. It is ideal for portable use because of its small size.

This antenna idea came from various websites where the metal slinky toy had been pressed into use for an antenna. The slinky suffers from corrosion and is really only suitable for indoor use.

What was needed was an outdoor, heavy duty, corrosion resistant slinky. The electric fence gate spring fitted the bill. Get ones that stretch up to 5 metres. They are available on line too.

Discard everything apart from the springs. Now build your dipole. The wire should be as long as your available space permits. I used about 5 metres on each leg.

The spring need not be stretched far but make sure the turns are not touching, even in strong wind.

My gate spring could not be soldered so the wires were attached with screw down chocolate blocks, well greased with silicone to slow corrosion at the contact points.

My antenna was mounted as an inverted vee with the ends about 2.5 metres above ground.
The centre feed was about 6 metres above the ground.
This configuration is likely to have a high radiation angle, good for more local contacts.
For a lower radiation angle, mount it vertically or as near to vertical as possible. An inverted L might also work but both these configurations might have more unbalanced feeder currents.

Using an antenna tuning unit suitable for balanced line, this could be brought to 1:1 SWR on 80, 40 and 20 metres but not 160 metres.
Using four springs might work for top band. "Fourspring Durch Technik"!

Within minutes, I had QSOs from the UK to Italy and the Channel Islands so the antenna works. Obviously a full size dipole will work better but this is a nice idea for a site with limited space. This whole exercise was done on guesswork. If I ever have time, I might use an antenna analyser to see if the design could be improved. Proper resonance on 80 metres would be a good start.

To make the antenna work better, experiment with the amount of spring stretch and the length of the wire sections.

I plan to raise the entire antenna using three poles, two at the ends and one in the centre. This should reduce losses, raise the feed impedance and improve the efficiency of the antenna. There is space for a longer antenna. This one was cut to length using all my available wire.

I have seen articles that recommend the loading coil goes in the middle of the wire stretch or at the feed point. I attended a lecture by an antenna specialist who made it clear that the high current parts of the antenna should be as large as possible so putting the loading coil at the feed point might tune correctly but will be less efficient.

{{antennas}}

File:G4JUV-Gate-Spring-Dipole-02.jpg

2011-05-12T12:58:02Z

G4juv: Category:Antennas

[[Category:Antennas]]

Gate Spring Dipole

2011-05-12T12:55:22Z

G4juv:

This is a dipole which uses farm gate springs as loading coils. You can get an 80 metre dipole into quite a small space. Of course you lose efficiency but this is for people with less than 40 metres of back garden.

[[File:Gate-spring-dipole.GIF]]

Visit your local farm supplies store or go on-line and buy two kits like this. Get stainless steel if you can.

[[File:Gate-spring-kit.JPG]]

Make the dipole using the longest wire length that will fit your limited space. Mount it as high as possible. Mine is set up as an inverted V.

Use an ATU to tune it up and you are done. If you have an antenna analyser, it should be possible to optimise the antenna by tweaking the wire lengths and the amount of stretch in the loading coils. This should result in a more efficient antenna.

[[File:G4JUV-Gate-Spring-Dipole-01.jpg]]

== More Details ==

This is an 80 metre dipole that fits in a small space. An ATU is needed and using the ATU, the antenna works on other bands too. It is ideal for portable use because of its small size.

This antenna idea came from various websites where the metal slinky toy had been pressed into use for an antenna. The slinky suffers from corrosion and is really only suitable for indoor use.

What was needed was an outdoor, heavy duty, corrosion resistant slinky. The electric fence gate spring fitted the bill. Get ones that stretch up to 5 metres. They are available on line too.

Discard everything apart from the springs. Now build your dipole. The wire should be as long as your available space permits. I used about 5 metres on each leg.

The spring need not be stretched far but make sure the turns are not touching, even in strong wind.

My gate spring could not be soldered so the wires were attached with screw down chocolate blocks, well greased with silicone to slow corrosion at the contact points.

My antenna was mounted as an inverted vee with the ends about 2.5 metres above ground.
The centre feed was about 6 metres above the ground.
This configuration is likely to have a high radiation angle, good for more local contacts.
For a lower radiation angle, mount it vertically or as near to vertical as possible. An inverted L might also work but both these configurations might have more unbalanced feeder currents.

Using an antenna tuning unit suitable for balanced line, this could be brought to 1:1 SWR on 80, 40 and 20 metres but not 160 metres.
Using four springs might work for top band. "Fourspring Durch Technik"!

Within minutes, I had QSOs from the UK to Italy and the Channel Islands so the antenna works. Obviously a full size dipole will work better but this is a nice idea for a site with limited space. This whole exercise was done on guesswork. If I ever have time, I might use an antenna analyser to see if the design could be improved. Proper resonance on 80 metres would be a good start.

To make the antenna work better, experiment with the amount of spring stretch and the length of the wire sections.

I plan to raise the entire antenna using three poles, two at the ends and one in the centre. This should reduce losses, raise the feed impedance and improve the efficiency of the antenna. There is space for a longer antenna. This one was cut to length using all my available wire.

I have seen articles that recommend the loading coil goes in the middle of the wire stretch or at the feed point. I attended a lecture by an antenna specialist who made it clear that the high current parts of the antenna should be as large as possible so putting the loading coil at the feed point might tune correctly but will be less efficient.

{{antennas}}

Gate Spring Dipole

2011-05-12T12:50:43Z

G4juv:

This is a dipole which uses farm gate springs as loading coils. You can get an 80 metre dipole into quite a small space. Of course you lose efficiency but this is for people with less than 40 metres of back garden.

[[File:Gate-spring-dipole.GIF]]

Visit your local farm supplies store or go on-line and buy two kits like this. Get stainless steel if you can.

[[File:Gate-spring-kit.JPG]]

Make the dipole using the longest wire length that will fit your limited space. Mount it as high as possible. Mine is set up as an inverted V.

Use an ATU to tune it up and you are done. If you have an antenna analyser, it should be possible to optimise the antenna by tweaking the wire lengths and the amount of stretch in the loading coils. This should result in a more efficient antenna.

[[File:G4JUV-Gate-Spring-Dipole-01.jpg]]

== More Details ==

This is an 80 metre dipole that fits in a small space. An ATU is needed and using the ATU, the antenna works on other bands too. It is ideal for portable use because of its small size.

This antenna idea came from various websites where the metal slinky toy had been pressed into use for an antenna. The slinky suffers from corrosion and is really only suitable for indoor use.

What was needed was an outdoor, heavy duty, corrosion resistant slinky. The electric fence gate spring fitted the bill. Get ones that stretch up to 5 metres. They are available on line too.

Discard everything apart from the springs. Now build your dipole. The wire should be as long as your available space permits. I used about 5 metres on each leg.

The spring need not be stretched far but make sure the turns are not touching, even in strong wind.

My gate spring could not be soldered so the wires were attached with screw down chocolate blocks, well greased with silicone to slow corrosion at the contact points.

My antenna was mounted as an inverted vee with the ends about 2.5 metres above ground.
The centre feed was about 6 metres above the ground.
This configuration is likely to have a high radiation angle, good for more local contacts.
For a lower radiation angle, mount it vertically or as near to vertical as possible. An inverted L might also work but both these configurations might have more unbalanced feeder currents.

Using an antenna tuning unit suitable for balanced line, this could be brought to 1:1 SWR on 80, 40 and 20 metres but not 160 metres.
Using four springs might work for top band. "Fourspring Durch Technik"!

Within minutes, I had QSOs from the UK to Italy and the Channel Islands so the antenna works. Obviously a full size dipole will work better but this is a nice idea for a site with limited space. This whole exercise was done on guesswork. If I ever have time, I might use an antenna analyser to see if the design could be improved. Proper resonance on 80 metres would be a good start.

To make the antenna work better, experiment with the amount of spring stretch and the length of the wire sections.

I plan to raise the entire antenna using three poles, two at the ends and one in the centre. This should reduce losses, raise the feed impedance and improve the efficiency of the antenna. There is space for a longer antenna. This one was cut to length using all my available wire.

I have seen articles that recommend the loading coil goes in the middle of the wire stretch or at the feed point. I attended a lecture by an antenna specialist who made it clear that the high current parts of the antenna should be as large as possible so putting the loading coil at the feed point might tune correctly but will be less efficient.

Gate Spring Antenna

2011-05-12T12:50:07Z

G4juv: moved Gate Spring Antenna to Gate Spring Dipole: The new name better describes the article.

#REDIRECT [[Gate Spring Dipole]]

Gate Spring Dipole

2011-05-12T12:50:07Z

G4juv: moved Gate Spring Antenna to Gate Spring Dipole: The new name better describes the article.

== The Gate Spring Dipole ==

This is a dipole which uses farm gate springs as loading coils. You can get an 80 metre dipole into quite a small space. Of course you lose efficiency but this is for people with less than 40 metres of back garden.

[[File:Gate-spring-dipole.GIF]]

Visit your local farm supplies store or go on-line and buy two kits like this. Get stainless steel if you can.

[[File:Gate-spring-kit.JPG]]

Make the dipole using the longest wire length that will fit your limited space. Mount it as high as possible. Mine is set up as an inverted V.

Use an ATU to tune it up and you are done. If you have an antenna analyser, it should be possible to optimise the antenna by tweaking the wire lengths and the amount of stretch in the loading coils. This should result in a more efficient antenna.

[[File:G4JUV-Gate-Spring-Dipole-01.jpg]]

== More Details ==

This is an 80 metre dipole that fits in a small space. An ATU is needed and using the ATU, the antenna works on other bands too. It is ideal for portable use because of its small size.

This antenna idea came from various websites where the metal slinky toy had been pressed into use for an antenna. The slinky suffers from corrosion and is really only suitable for indoor use.

What was needed was an outdoor, heavy duty, corrosion resistant slinky. The electric fence gate spring fitted the bill. Get ones that stretch up to 5 metres. They are available on line too.

Discard everything apart from the springs. Now build your dipole. The wire should be as long as your available space permits. I used about 5 metres on each leg.

The spring need not be stretched far but make sure the turns are not touching, even in strong wind.

My gate spring could not be soldered so the wires were attached with screw down chocolate blocks, well greased with silicone to slow corrosion at the contact points.

My antenna was mounted as an inverted vee with the ends about 2.5 metres above ground.
The centre feed was about 6 metres above the ground.
This configuration is likely to have a high radiation angle, good for more local contacts.
For a lower radiation angle, mount it vertically or as near to vertical as possible. An inverted L might also work but both these configurations might have more unbalanced feeder currents.

Using an antenna tuning unit suitable for balanced line, this could be brought to 1:1 SWR on 80, 40 and 20 metres but not 160 metres.
Using four springs might work for top band. "Fourspring Durch Technik"!

Within minutes, I had QSOs from the UK to Italy and the Channel Islands so the antenna works. Obviously a full size dipole will work better but this is a nice idea for a site with limited space. This whole exercise was done on guesswork. If I ever have time, I might use an antenna analyser to see if the design could be improved. Proper resonance on 80 metres would be a good start.

To make the antenna work better, experiment with the amount of spring stretch and the length of the wire sections.

I plan to raise the entire antenna using three poles, two at the ends and one in the centre. This should reduce losses, raise the feed impedance and improve the efficiency of the antenna. There is space for a longer antenna. This one was cut to length using all my available wire.

I have seen articles that recommend the loading coil goes in the middle of the wire stretch or at the feed point. I attended a lecture by an antenna specialist who made it clear that the high current parts of the antenna should be as large as possible so putting the loading coil at the feed point might tune correctly but will be less efficient.

Gate Spring Dipole

2011-05-12T12:49:30Z

G4juv: Created page with "== The Gate Spring Dipole == This is a dipole which uses farm gate springs as loading coils. You can get an 80 metre dipole into quite a small space. Of course you lose efficien..."

File:G4JUV-Gate-Spring-Dipole-01.jpg

2011-05-12T12:38:25Z

G4juv: Category:Antennas

[[Category:Antennas]]

File:Gate-spring-kit.JPG

2011-05-12T12:32:11Z

G4juv: Category:Antennas

[[Category:Antennas]]

File:Gate-spring-dipole.GIF

2011-05-12T12:29:41Z

G4juv: Category:Antennas

[[Category:Antennas]]

T

2011-05-12T12:16:36Z

G4juv: /* T */

{{glossary}}

==T==

'''Telegraphy''' ; text based [[Modes |modes]]. Includes morse and RTTY.

'''[http://en.wikipedia.org/wiki/Vacuum_tube Thermionic Valve]''' : (Also known as an '''Electron Tube''' or a '''Vacuum Tube'''). A device that creates or modifies an electrical signal through the movement of electrons in a low pressure (vacuum) space.

'''THROB''' : An MFSK digital mode based on tone pairs.

'''TNC''' : '''T'''erminal '''N'''ode '''C'''ontroller - a device used in packet radio that disassembles and re-assembles packets of data.

'''TOR''' ('''T'''eleprinting '''O'''ver '''R'''adio): Used in three digital modes; AMTOR, PACTOR and G-TOR.

'''Toroid''' : A donut-shaped solid usually constructed of ferrite, used as the former for transformers and inductors'

'''[[Attenuators | T pad]] ''' : one of the possible configurations used in [[Attenuators]]

'''Transceiver''' : A radio that has both a transmitter and a receiver, which either share common circuitry or a common housing or both.

'''Transient''' : A short spike or trough on a power line, usually lasting for a few microseconds.

'''[[Feedlines | Transmission Line]]''' : Also known as [[Feedlines |feedline]].

'''Tuned Circuit''' : A capacitor and an inductor, usually in parallel. The circuit responds strongly at its resonant frequency and is used to select or tune in wanted signals.

'''[[TVI]]''' : Interference to television reception.

'''TX''' : Abbreviation for transmit or transmission

Portable antenna

2010-12-12T08:20:01Z

G4juv:

Portable antennas are designed to be easily transported from one location to another, and can be set up and taken down quickly. Portable antennas are frequently used when camping or backpacking. See [http://adventure-radio.org/ Adventure Radio Society] and [[Trail-Friendly Radio]] for more information.

Portable antennas should not be confused with [[mobile antenna|mobile antennas]], which are designed to be used while in motion.

== Simple Dipoles ==

== Crappie Pole technique ==

== Portable Verticals ==

{{antennas}}

User:G4juv

2010-12-12T08:17:25Z

G4juv: Created page with "== G4JUV == Neil is located in Beccles, Suffolk, UK."

== G4JUV ==

Neil is located in Beccles, Suffolk, UK.