Talk:Loading coil

Submarine power cable loading

Loading coils for power transmission systems? Can anyone substantiate this statement? While capacitors are installed for power factor correction, I am unaware of the use of coils in power distribution. LorenzoB 04:43, 13 January 2007 (UTC)

Distribution, no; underwater transmission, yes. See Cross-Skagerak for an example of how excess capacitance is dealt with when the distance is too great for load coils, and Submarine power cable for a brief but more general discussion.

Jim.henderson 00:08, 14 January 2007 (UTC)

Both those articles say that the solution for power is DC transmission, not loading coils. I cannot get any ghits on the subject either (except for Wikipedia, its mirrors, forks and copiers). I've tagged it as a disputed fact.

SpinningSpark 23:43, 28 September 2008 (UTC)

Oops, forgot about this for a while. Yes, articles about individual underwater lines are about notable ones, which is to say big long ones, and big long ones have to be DC or their capacitance will be too big a problem. Hundreds of underwater lines, maybe thousands, are a few miles or kilometers, including the one from Glen Cove, New York to Rye, New York, and those are almost all AC and thus, at least to my limited understanding, are the ones that (a) need some sort of compensation for capacitance and (b) can have it without the expense of DC. Those get little bragging in technical journals or political controversy or other publicity, so we need a general source, which I haven't been able to find, alas, so it doesn't really belong in the article. Jim.henderson (talk) 18:35, 9 October 2008 (UTC)

Since water has a dielectric constant of about 80 at low frequencies (even much higher than 60Hz), capacitance adds up fast. Gah4 (talk) 20:19, 19 October 2020 (UTC)

Images?

Does anyone have any images of this because I want to know what they look like. —Preceding unsigned comment added by Komomisp (talk • contribs) 19:19, 7 September 2008 (UTC)

Description missing

This article does a good job of describing how a loading coil is used, but not what it IS, other than to say "it's a coil", which is obvious from the name. The picture makes the reader think of a transformer.

Wikipedia articles can't be written for people who already understand these things.

I barely have time to write this note, but somebody say that it's a electricity-conducting coil (as opposed to a coil of rope), what it's wrapped around (plastic), HOW it increases inductance, and why inductance is a good thing. And take a photo of one they might have seen on a cable, not just a schematic. HelviticaBold 00:18, 17 March 2012 (UTC)

It is just a coil - I think you are confusing yourself by thinking this is more complicated than it actually is. It is a coil of conducting wire, as coils always are in electrical circuits. It is really counterproductive to explain "coil" in all the thousands of articles in which it appears, and if there were any doubt, the links to coil and inductor in the first sentence of the article will instantly make it clear. I agree the diagram of the balanced line could lead to confusion so I have added some explanation of this format. There is indeed some transformer action betweeen the two windings, but it is not actually a transformer as it does not link to any cicuit other than the one it is in.

You say you are in a hurry - I don't think you can have read the article very thoroughly. The section on Oliver Heaviside does a good job of explaining why increasing inductance is a good thing. The reason for the Heaviside condition is deeply mathematical and I am not aware of any simple "hand waving" explanation. Those interested can follow the link.

A picture would be good, but there is currently nothing suitable on Commons. SpinningSpark 10:11, 17 March 2012 (UTC)

But there is on Flickr, I'll upload something. SpinningSpark 14:11, 17 March 2012 (UTC)

Recharger

This is the type of instrument you would need to recharge car batteries, along with a pulsating current to create a fluctuating current of some sort or current which goes one direct ie direct current flow. — Preceding unsigned comment added by Mvdc1980 (talk • contribs) 16:28, 10 May 2014 (UTC)

typo

"A loading coil is not a transformer to provide coupling to another other circuit."

If the page weren't "protected," I'd have made the simple edit, myself. Instead, I should suggest another proofreading by whomever "protected" the page. 75.110.100.120 (talk) 17:55, 13 June 2015 (UTC)

Semi-protected edit request on 7 April 2016

The second sentence in this article:

A loading coil is not a transformer to provide coupling to another other circuit.

Should be changed to

A loading coil is not a transformer and it doesn't provide coupling to another circuit.

Because: 1) "another other" is grammatically incorrect 2) The current wording is ambiguous, as it isn't clear whether the loading coil is a transformer that doesn't provide coupling, or isn't a transformer but provides coupling. Rewording it in the stated way removes this ambiguity.

Note: The word "transformer" could be linked to the Wikipedia page on transformers. 167.220.196.248 (talk) 12:20, 7 April 2016 (UTC)

Done, with some slight copyediting. SpinningSpark 17:10, 7 April 2016 (UTC)

Semi-protected edit request on 9 April 2016

I would like that you add loading coils to the category 'Serbian inventions' as they were invented by Mihajlo Pupin. Thank you. Jwred (talk) 00:59, 9 April 2016 (UTC)

Pupin's claim to invention is disputed, as explained in the article. Even if it was his invention, he did so as an American citizen on US soil, so claiming it as a Serbian invention is dubious at best. I'll leave it to someone else to close this request as I have a strong contribution to this article, but I do not support the request. SpinningSpark 10:14, 9 April 2016 (UTC)

 Not done - as explained above, the invention is in dispute and Pupin became a US citizen in 1883 - 16 years before he lodged his patent application - so if anything, it was an American invention - Arjayay (talk) 12:47, 9 April 2016 (UTC)

Why Protected

...for so long? It's an antenna feature. 178.39.122.125 (talk) 23:26, 28 January 2017 (UTC)

I've removed the protection, it probably doesn't need it any more. Although I don't quite understand why it being "an antenna feature" is a rationale for unprotecting. SpinningSpark 00:58, 29 January 2017 (UTC)

Loading coil is not a transformer

The sentence is unnecessary and I would recommend its deletion: "A loading coil is not a transformer as it does not provide coupling to another circuit."

Coils are common elements in nearly all manner of electrical and electronic circuits. Their use in transformers is a special case. — Preceding unsigned comment added by Rico402 (talk • contribs)

The form of loading coil used on balanced lines is easily mistaken for a transformer. The article concentrates on this form and historically it is the origin of loading coils. I think it is useful to keep this sentence, but it might be better to move it out of the lead into the telephone lines section. Or into the caption of the circuit diagram showing this use. SpinningSpark 15:31, 16 January 2018 (UTC)

Agreed, Rico402 (talk) 20:49, 16 April 2018 (UTC)

Sentence deleted from intro as unnecessary and possibly confusing. Added the following to the "Telephone lines" section: "(Despite the use of common cores, such loading coils do not comprise transformers, as they do not provide coupling to other circuits.)" Hopefully this addresses any confusion re the common cores shown in the circuit diagram.

Cheers, Rico402 (talk) 17:42, 30 May 2018 (UTC)

English variety

@Kbrose: I propose that this article be standardised on British English. I wrote the great majority of this article and I have been using British English (as shown by "favour" for instance). I realise that the word "center" appears in the article (in an image caption for instance) but this is a comparatively recent addition post-dating my work. The subject is by no means an exclusively American one; it is international, and the earliest proponent of loading was the British engineer Oliver Heaviside. SpinningSpark 16:53, 20 August 2019 (UTC)

Fine with me. --Chetvorno^TALK 17:11, 20 August 2019 (UTC)

The American spelling variation was already established as of 2015-03-08T13:07:32, which you changed to British later. Kbrose (talk) 17:32, 20 August 2019 (UTC)

@Kbrose: I did? I don't recall ever changing any spelling on the page until I reverted your change yesterday. The version you refer to is an edit by you in which the word "favour" is already present. Anyway, I am not trying to start an argument about who wrote what when. The point is, the article currently does not have a consistent spelling style established. I am proposing British English on the basis that the great majority of the article was written in British English. SpinningSpark 10:53, 21 August 2019 (UTC)

Lead picture removal

Original lead image

@Chetvorno: pinging you because you seem to be knowledgable in this area. Do you agree with the removal of the lead picture in this edit? The reason given is that it is a phasing coil, not a loading coil. As a photograph, it is a nice image and it's a shame if we can't use it.

Image in antenna section

If you agree, why is the image in the antenna section ok and the lead one is not? As I understand it, a phasing coil joins two sections of electrically short antenna in phase, effectively forming an antenna array. Typically, the two sections are the same length. Neither of the images look like they meet this requirement so the identification as a phasing coil needs justifying. SpinningSpark 17:00, 16 October 2020 (UTC)

As an editorial question, isn't it meant "to make a physically short antenna resonant at a lower operating frequency"?

Or at least, "to make an electrically short antenna resonant at a lower operating frequency"? Because it is a little fuzzy as to the "its" that is resonant. Steve (talk) 21:21, 21 July 2023 (UTC)

@Gah4: who also might know something about antennas. SpinningSpark 17:36, 16 October 2020 (UTC)

I haven't thought about this for a while. I think the ARRL handbook has a good description. As well as I remember, they are loading coils bottom, middle, or top. Top works better, but has problems because it puts weight in the wrong place, especially for mobile (car) use. Bottom is more convenient, but not as good. Gah4 (talk) 20:24, 16 October 2020 (UTC)

Frequency of operation matters, typically loading coils are only necessary on mobile antennas operating on lower frequencies (< 100 MHz) where wavelength makes full size antennas like a 1/4 wave whip impractical. The cellular antenna in the removed image operates around 860 MHz and the phasing coil does not function as a loading coil despite the mechanical similarity. The second image of a citizens band (27 MHz) antenna is a good example of a loading coil used to make the physical length of the antenna shorter than the electrical length.

The coil in the cellular antenna is not a loading coil because it is not used to make the antenna physically smaller. The cellular antenna is a full size 1/4 wave antenna below the coil and a full size 5/8 wave antenna above the coil. The only function of the coil is to feed the two antenna elements in phase.DelosInc (talk) 02:25, 17 October 2020 (UTC)

@DelosInc: For transparency, are you the same person who removed the image? SpinningSpark 11:20, 17 October 2020 (UTC)

I did a web search for cell car roof antenna "phasing coil", as I have never had one. I think I now believe that it is two different names for the same thing. If an antenna is too short, then the reflection off the end will come back too soon. A phase shift fixes that, and note that the phase shift happens both ways. So, a loading coil is always adjusting phase. A phasing coil changes the load, as seen by the source. Is there a separate article for phasing coil? Gah4 (talk) 14:10, 17 October 2020 (UTC)

OK, I now made a redirect from Phasing coil with edit summary and talk page suggesting discussion here. Unless someone wants to make a separate page for it ... Gah4 (talk) 14:15, 17 October 2020 (UTC)

I had never heard of a "phasing coil" until now, but I googled it too [1], [2], [3]. It says they are widely used with 800 MHz car top cell phone antennas. You might be right that it is just another name for a loading coil, but it looks a little different to me. A loading coil is usually used with an electrically short whip, < $\lambda$/4. The phasing coil is used between two $5\lambda$/8 whips (the length at which a monopole has maximum gain) so the total antenna length is greater than a wavelength. This source draws a distinction between them: "Since at UHF the quarter wave whip is physically small, techniques can be used to increase the gain. Two 5/8 wave monopoles can be stacked with a phasing coil between them. This is effectively an antenna array, with a gain of 5 dB." The phasing coil's purpose is not to make the antenna resonant at a length shorter than its resonant frequency, like a loading coil, but to shift the phase so that the current standing waves in the portion of the antenna above and below the coil are in phase, so their radio waves will reinforce.

Anyway, I agree this is the appropriate redirect for Phasing coil, but maybe there should be a short separate section describing them. I think the deleted image could be restored, editing the caption to say this is a phasing coil, not a loading coil. --Chetvorno^TALK 17:55, 17 October 2020 (UTC)

At low frequencies, loading coils allow a shorter antenna to match impedance and radiate well. At higher frequencies phasing coils allow a longer antenna to match impedance and radiate well. There are center loaded CB antennas. Gah4 (talk) 19:21, 17 October 2020 (UTC)

Sure, amateurs and CBers have used center loaded whips for a long time. Center loading requires a larger coil than base loading, to tune out the smaller capacitance of the shorter section of the antenna above the coil. It's also structurally more difficult and expensive to make. If both types can bring the antenna to resonance, why is center loading used? Because it improves the current distribution on the whip, increasing the gain, and also increases the low radiation resistance of a short whip, making it easier to feed, according to ARRL, p. 16-5. Base loading does not change the current waveform on the antenna, it is still a sine wave.

It's clear from the sources that in cell phone antennas, like in CB antennas, the function of the phasing coil is not just to tune the antenna to resonance, which could be done with a cheaper base loading coil, but to increase the gain by altering the current distribution. This article should have a section on center loading and phasing. --Chetvorno^TALK 05:31, 19 October 2020 (UTC)