User talk:Interferometrist

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User talk:Interferometrist/Archive01 - ending 21 April 2011.

Equalization

Since you seem to know as much about the subject as anyone, I am VERY much in favor of your making an outline of what a general article on equalization might look like. I'd like the pages pertaining to basic sound recording and processing concepts to be intelligible to your average non-engineer music fan who comes across terms like "EQ". Never thought this would be such a battle royal, and not sure it matters as much now that there's a page dedicated to audio EQ, but still...

Here's what the page looked like before I decided to start making everyone angry: http://wiki.riteme.site/w/index.php?title=Equalization&diff=381129027&oldid=374320064

To your average person that reads as, "Say what?"

So, I guess I'm saying progress is possible. And also I'm saying, HELP! Fondly,--Atlantictire (talk) 03:34, 24 April 2011 (UTC)

Do you mind if we re-work the lead? You added a lot of excellent information, but it's bit intimidating if you're coming to the page just to get a general idea of what EQ is. I always try to keep in mind: encyclopedia, poor bloke who just wants to know what that nob on a guitar does. Would you mind if I fiddled with it some so that we can give the poor bloke the quick answer he's looking for, then move into the more technical language?--Atlantictire (talk) 16:49, 24 April 2011 (UTC)

Of course not (and you don't really need to ask around here!). But are you moving some of the material, simplifying it, or just proposing to eliminate concepts that are above a certain level? Anyway, go ahead -- after all the worst that can happen is a revert and you're already used to that ;-) -- or seriously, just write it and I'll agree or respond with a compromise version etc. I'm waiting..... Interferometrist (talk) 16:56, 24 April 2011 (UTC)

Thanks! I'll work with it and then you can tell me what you think. Basically, I try to start by explaining things in terms of "pitch", "loudness" and "sound" before discussing "frequency", "amplitude" and "signal".--Atlantictire (talk) 16:59, 24 April 2011 (UTC)

Ok. Though I should also say that I don't think using those words makes it like a "textbook," though I can appreciate that it's nice for an article to be readable by those who are going to look it up. But there are all levels of articles on Wikipedia, and if you look up a real specialized term you'll get a description in terms of less specialized terms which are still obscure to the "average guy." But anyway, you'll do better with this than I did since I was thinking about what was correct and important, than the best way to explain it to dummys. Good luck -- Interferometrist (talk) 17:34, 24 April 2011 (UTC)

There are a few things in the lead where I don't know what you mean. I'll paste them to the talk page so that you can explain them.--Atlantictire (talk) 17:48, 24 April 2011 (UTC)

Ah, tone bloody tone. I can definitely see your point and tone is a perfectly good term, but there's a good chance you won't understand it correctly unless you are already familiar with some basic EQ concepts. There are fewer garden paths to go down with "pitch" and "loudness", whereas there are many many many ways to misunderstand tone. Speaking from experience!--Atlantictire (talk) 04:59, 25 April 2011 (UTC)

I never said write an article on tonal balance! Good sir, sometimes your replies read as if you've only glanced and what I've written and haven't actually read it. If this is the case, it's going to make this process much more difficult and take much longer. :-)--Atlantictire (talk) 19:06, 26 April 2011 (UTC)

Right. You said to write a section on it on the other page so that it could be linked to. Again, the section should be in the eq (audio) article itself. And I do read what you write and value communication: you must have noticed that all this is getting settled on the talk pages and not through revert wars with insulting edit summaries, ok? :-) --Interferometrist (talk) 20:44, 26 April 2011 (UTC)

Tone balance

In favor of changing pitch volumes to "tone balance". It could read as "Audio engineers initially used equalization to improve the fidelity of an audio system, so that the tone balance--[Interferometrist's definition]--as heard through speakers would better resemble that of the original sound."

Or if you like you could write a lengthier explanation of tone balance in the body of the article, and then link to that part of the article. Up to you. :-)--Atlantictire (talk) 06:54, 27 April 2011 (UTC)

Ok, we're converging toward something. I don't have much time now but yes YOU go ahead and write something that seems right and (of course) you will get my feedback (and hopefully from others too). I'm not sure a little phrase in the lede needs to link to anything since it won't sound so technical that someone thinks the article is too intimidating, and the meaning of any such terms will become clear shortly thereafter (though something less technical needs to be added before jumping into the part on filter functions). Is that good? Interferometrist (talk) 09:22, 27 April 2011 (UTC)

Si!--Atlantictire (talk) 19:40, 27 April 2011 (UTC)

Speaking of our fine friend tone, this is interesting: there's someone editing the Effects unit article who is hell bent on changing its classification system ("it's all modulation, man!"). While I don't necessarily agree with how he wants to classify things, I do think the categories are sorely in need of a review.--Atlantictire (talk) 14:22, 29 April 2011 (UTC)

RING LASER GYRO

---

Hello interferometer! Thanks for the talk item. Yes, I worked with the HeNe for many years; in fact Rigden and I have the patent on it. An account of the discovery is on the IEEE website in the Global History Network. Don't know if it's accessible to non-members. Can send you a copy if you can't access the site. Ring Laser Gyros generally use the 6328 wavelength because is is shorter than the 1.15 micron wavelength so gives higher sensitivity. See "Fundamentals of the Ring Laser Gyro" by Frederick Aronowitz, <ftp://ftp.rta.nato.int/PubFulltext/RTO/AG/RTO-AG-339/$AG-339-03.PDF> . Not sure how to add footnotes so didn't. Withead (talk) 14:58, 8 May 2011 (UTC)

Hello again, Yes, there is a lot of confusion about the invention of the red laser which has become exceedingly difficult to clear up. It arises because both lasers use the same medium, helium and neon, even though the inversion that leads to gain at 0.633 microns is with respect to a completely different upper energy level of neon. I gave up writing "letters to the editor" about the misconception years ago. It is my hope that these contributions to the Wikipedia article will help clarify the issue. I plan to modify some of the material in the "History...." section which might shed more light on the issue and put things in proper perspective. Withead (talk) 01:34, 11 May 2011 (UTC)

Linear filter

I think it might be useful to have a crack at explaining what a linear filter does to a signal in the "Terminology" section of the EQ article. I'm new to this concept, so I'm wondering: is it overly simplistic/wrong to say that the parameter (amplitude, frequency, phase) modified by a linear filter is directly proportional to that of the input?--Atlantictire (talk) 01:47, 17 May 2011 (UTC)

Re fair use: I know you're allowed to upload snippets of copywrited song to articles about the songs, but I don't know if you could, say, use a 15 second sample of "Living On a Prayer" in the Talk Box article. My best guess would be you can't. I've included sound samples on the Effects unit page, but none are actually songs... just brief chord progressions or sustained notes. Once you have the sample you'd like to use, you convert it to an ogg file and upload it to wikipedia commons. This is a slightly involved process that requires you choose a licensing agreement and attach it to your file... but the commons walks you through it.

Ok, so a basic linear filter used in audio equalization is just something that determines the frequency response of a signal (i.e. how loud the sound is at a given frequency). It sounds like either dB or frequency can be independent variables. Explaining that in conjunction with a graph would be excellent. Is this a good one: [File:Butterworth response.svg]? Of course, a math illiterate dumbo like me is going to ask, well then why is the graph curved. Also, would you want to go into the circuitry a little bit? I always find that really interesting.--Atlantictire (talk) 16:09, 18 May 2011 (UTC)

Fidelity of re-contstructed holograms

I added these comments onto the Holography discussion page in response to your comments, and am putting them here as well for your attention:

From Hariharan, Optical Holography. page 88

"With any practical recording medium, its MTF will, in general, affect the resolution as well as the intensity of the reconstructed image."

If the scene being recorded consists of two point sources which produce essentially Young's fringes, and if the spacing of these fringes is well below the resolution of the recording medium, then no fringes will be recorded, and no image will be obtained. Any feature in a complex scene with the same separation as the point source will likewise not be reconstructed. Epzcaw (talk) 23:37, 18 May 2011 (UTC)

Gaussian beam

Would you be willing to help correct the Gaussian beam page? I believe the normalization is incorrect in the section on Hermite-Gaussian modes, and I agree that the form is needlessly awkward. I would vote for one of the alternates you suggested except I'm concerned that the normalization may be incorrect in those also. I'm willing to propose corrections but I'd like to have them checked before updating the page. I also agree that the mention of the uncertainty principle doesn't belong. Mwregehr (talk) 17:36, 12 August 2011 (UTC)

Hi, thanks for the interest and invitation. I haven't been able to do much with wikipedia lately, but yes, in principle I could help enhance the article. The specifics need to be discussed on the article's talk page so that everyone concerned can be involved in deciding the eventual content, so I will try to post something there fairly soon, so check that page again. By normalization, I assume you mean that the u_nm functions should have their power |u|^2 integrated over x and y (or just x for the separate x or y function) at any z equal to 1. The form given there based on the q parameter makes it difficult (without doing a bit of algebra) to see whether it corresponds to the forms in my reference books, but I'll work on it sometime. I think a much more transparent equation should be included in which the amplitude and phase factors in the expression are clearly identifiable, even if using the complex q is more elegant in some respect, so I would replace that equation (or at least add the more readable one). And when I have time I could ADD some more useful explanation concerning the Gouy phase, but removing the current misleading/confusing text got me to waste a bunch of time reading an esoteric paper and arguing with someone over philosophy, so I gave up on that! Cheers, Interferometrist (talk) 12:34, 16 August 2011 (UTC)

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Cut-and-Paste

Hi,

You did a rather crude cut-and-paste of material from the Common path interferometer article to Sagnac effect. The material that you cut out relied on the illustration in the Common path interferometer article, and made references to other material in the Common path interferometer article that do not exist in the Sagnac effect article.

Also, the whole point of the zero area Sagnac interferometer is that, while being a common path interferometer that exhibits the high stability inherent to the Sagnac configuration, it does not exhibit the Sagnac effect because of the net zero enclosed area, so its presence in an article about the Sagnac effect is confusing without some degree of rewrite.

We obviously need to chat about this some. If you want this material in Sagnac effect, the material has to be re-written to make sense within the context of this article. I can also draw a custom illustration for you to illustrate how the zero area is achieved.

Stigmatella aurantiaca (talk) 23:17, 9 February 2013 (UTC)

Dubious

Hi again. I also notice that you applied a "Dubious" tag to a section in Sagnac effect dealing with an interesting modification of the Sagnac interferometer that uses a looped, moving optical fibre. The effect is quite straightforward, but without an illustration the whole section is rather confusing. Perhaps we can work together to improve it? I can draw an illustration, and you can rewrite the section?

I might mention, by the way, that anti-relativity nuts seem to think this simple variant of the standard Sagnac interferometer makes some sort of case against relativity. If we explain its operation clearly enough, perhaps we can do something to help silence these cranks. Stigmatella aurantiaca (talk) 23:49, 9 February 2013 (UTC)

Original research

Please do not add original research or novel syntheses of published material to articles as you apparently did to Sagnac effect. Please cite a reliable source for all of your contributions. Thank you. - DVdm (talk) 17:21, 10 February 2013 (UTC)

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Helmholtz reciprocity for magnetic field

Thank you for this valuable edit. It is good to have your expertise. Perhaps you can say whether, if the magnetic field is of known form, there is some modification of the Helmholtz principle that can account for its effects on a ray of light?Chjoaygame (talk) 01:22, 24 February 2014 (UTC)

Hi, thank you. Yes I do have expertise is in electromagnetism, but not really concerning the reciprocity principle. I just knew enough to distinguish a mistake. Although magnetic fields are involved (obviously) in EM waves, they are created by changing electric fields and then create electric fields and the net effect retains reciprocity in terms of electric fields and currents. It is when you have a static magnetic field acting on a material to obtain the Faraday effect that you create anti-reciprocity (which permits an optical isolator or circulator). I'm not prepared to edit the page any further but if you'd like to research this further and add any such wording, please do so (I'll surely see your edit!). Good luck, Interferometrist (talk) 15:04, 27 February 2014 (UTC)

Thank you for this. I am not remotely near your level of expertise in this. I just wrote "in a simple form" to indicate that there is some closely related principle, such as the one that you have pointed to, anti-reciprocity, that does deal with the presence of magnetic fields. I regarded that as a complication of reciprocity tightly construed, but still a form of 'reciprocity' loosely speaking. I didn't, and still don't, think it necessary to fill in the detail. As for optical activity, it seems I guessed wrongly. Optical reciprocity, as I understand it, is a special case of electro magnetic reciprocity, and has special features that do not hold for the general case.Chjoaygame (talk) 00:09, 28 February 2014 (UTC)

I have tentatively added the following sentence. "For a known magnetic field, a modified version of the principle may apply." If it needs editing or deletion, please go ahead as you think fit. As a curiosity, there is a current article in the American Journal of Physics [1] that explains rather precisely how under some circumstances, motion of the medium can mess up optical reciprocity. I don't think this calls for an edit to the article.Chjoaygame (talk) 12:51, 28 February 2014 (UTC)

Hi. I applaud your interest in the subject and will mention a few things. But the statement you added to the page isn't really accurate or helpful and I'd advise you to revert it (which is nicer than someone else doing so :-)

I looked at your reference, but mainly jumped to the section in question regarding reciprocity. I believe the author is mistaken in discussing the reciprocity principle in this situation. AFAIK the principle only applies to linear time-invariant systems, and a changing system (with movement inside of it) would be excluded.

In the course of looking through the references (perhaps it was cited by the paper you mentioned?) I found this rather good review article (though again I have only skimmed it) on the subject which specifically deals with the question of magneto-optics in section 9. Let me know and I could help if you're unable to access the text: http://iopscience.iop.org/0034-4885/67/5/R03/ - Interferometrist (talk) 18:10, 2 March 2014 (UTC)

Thank you for this. I have undone my edit about magnetic effects. Without your expertise myself, I agree that "the principle only applies to linear time-invariant systems, and a changing system (with movement inside of it) would be excluded". I seem to recall that I listed Potton's important review in the references somewhere, and I have a copy of it; but I confess not to have digested it all. Obviously, further contributions from you will be very good.Chjoaygame (talk) 01:44, 3 March 2014 (UTC)

Thanks. I should add that my remark about the author being "mistaken" in the paper you referred me to were a bit rash. I looked at it again. The author wasn't under any illusion about an internally moving system following reciprocity and didn't present the contrary conclusion with any degree of surprise or novelty. In fact it was his very intention to find a "light diode" (usually called an "optical isolator") and identified a way of doing it using a moving Bragg reflector. So he found exactly what he was looking for using one case in which reciprocity is not expected (the other being magneto-optics). Hopefully he isn't reading this ;-)) -- Interferometrist (talk) 02:13, 3 March 2014 (UTC)

I didn't get the message that you were referring to the recent article I mentioned here, about a light diode, and so I didn't catch on to what you meant anyway! Somehow I feel that a known static magnetic field would have some kind of simple principle complementary to reciprocity and not too different from it, that might be mentioned with the right wording? My edit failed to require the magnetic field to be static; is that what you found unsatisfactory?Chjoaygame (talk) 02:23, 3 March 2014 (UTC)

No I'm sorry, but there just isn't anything of the sort. The question isn't the magnetic field per se but a magneto-optical component in a static magnetic field. By itself it is anti-reciprocal. But combined with a pair of polarizers (to create an optical isolator) it is neither. It simply isn't reciprocal, even though its components are linear and unchanging, and that is possible BECAUSE of the magneto-optical element, which is I believe the only way you can violate reciprocity under those other conditions (which is why an optical isolator is considered a rather "exotic" component, and can't be made in an easier way). That is as far as you can go with it. Either reciprocity holds (as it does under some rather general conditions) or it doesn't. There is no such thing as a "correction term" to it. Interferometrist (talk) 03:36, 3 March 2014 (UTC)

Thank you for that careful explanation. Such is life!

There is also a separate article called Helmholtz reciprocity that I wrote that I would be grateful if you would check and correct as appropriate or whatever you find time to do. It has a few more references. It took me a little struggle to get optical reciprocity explicitly and separately stated into the general electromagnetic article. I don't draw too much attention to the Helmholtz reciprocity article, because there is a risk that someone might want to merge it or remove if they were provoked. I like the article to be there, because for an ignorant person such as myself, it is verging on too much of a struggle to see that optical reciprocity aka Helmholtz reciprocity is a special case of the general electro magnetic reciprocity, and an article on Helmholtz reciprocity under that name is an easy way out, when you just want to have some idea of what Planck is talking about when he uses Helmholtz reciprocity.Chjoaygame (talk) 06:04, 3 March 2014 (UTC)

I didn't actually start the Helmholtz reciprocity article myself. Someone had already started it, and I built on that.Chjoaygame (talk) 06:08, 3 March 2014 (UTC)

Since you are a pretty clued up fellow, perhaps you might kindly be willing to give me a comment as follows. I am aware that to suggest that there might be something that relates silly old classical physics to the wonders of God-given quantum mechanics is a sign of insanity if not a criminal offence punishable by being shot at dawn every morning for a month. But even so, I wonder if you might comment on the book by the brothers Grimes that I think you can download for free at http://en.bookfi.org/book/516304. I paid money for a pdf version some time ago but I am not permitted to send it to you, as I understand. I would be grateful for a comment from someone who knows a thing or two. I will not report you to the thought police if you make incorrect or unacceptable remarks.Chjoaygame (talk) 10:29, 3 March 2014 (UTC)

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Polarization

I am very glad that you appreciate my edits. I mainly translate from English to Chinese. Whenever I see places where references are needed and I can find good references, I would go ahead and add those references. --老陳 (talk) — Preceding undated comment added 19:08, 3 May 2014 (UTC)

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The rescue of polarisation

An invitation: Talk:Polarization_(waves)#bloated. 22:12, 14 July 2014 (UTC)

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Thanks, Interferometrist; I replied at Asidepa (talk). (Sorry, if I am doing this wrong; I'm a Wiki newbie.)

Thanks for the plot of Dipole antenna impedances; it is much appreciated. Similar plots are available in web searches, but not in Smith Chart format. Are you able to post that same data plotted on a Smith Chart, please?

(You can reply to me, Asidepa.) — Preceding unsigned comment added by Asidepa (talk • contribs) 20:59, 7 August 2015 (UTC)

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General expression for skin depth

I have made a proposal on Talk:Skin effect to suppress or delete the general expression for skin depth as published in Jordan in favor of your simplified version which is much easier to understand and readily reveals both the low frequency approximation and the high frequency limit. I have independently derived the result and verified that is exactly equivalent to the version in Jordan. I feel that we can do without the redundancy. Comments? Constant314 (talk) 16:15, 6 September 2015 (UTC)

Can you post your derivation? In general, I think it would be a good idea to stick to sources rather than derivations unless the derivation is posted on the talk page of the relevant subject. A.d.vannes (talk) 04:49, 12 April 2018 (UTC)

Hi, I'm not sure that Constant314 saw this, but as he said in the comment reverting your change, the exact equivalence of the two forms was attested to by both him and myself. My derivation of that equivalence was on some scrap of paper almost surely since discarded and although I could reproduce the algebra I don't really think I need to. It appears and we agreed that Wikipedia allows for such a change just involving straight-forward algebra. If you aren't sure then you should do the algebra yourself -- or subtract one form from the other and see if it can be non-zero. Likewise for the silicon example, it is permissible for editors to apply a formula in a specific case when the formula and data applied are uncontroversial. Wikipedia has enough errors that can be found, and your finding them is useful, but this isn't one of them. Interferometrist (talk) 13:26, 13 April 2018 (UTC)

The key steps are this

${\frac {1}{\left\lbrace \left[\left(1+\left({1 \over {\rho \omega \epsilon }}\right)^{2}\right)^{1/2}-1\right]\right\rbrace ^{1/2}}}={\frac {1}{\left\lbrace \left[\left(1+\left({1 \over {\rho \omega \epsilon }}\right)^{2}\right)^{1/2}-1\right]\right\rbrace ^{1/2}}}{\frac {\left\lbrace \left[\left(1+\left({1 \over {\rho \omega \epsilon }}\right)^{2}\right)^{1/2}+1\right]\right\rbrace ^{1/2}}{\left\lbrace \left[\left(1+\left({1 \over {\rho \omega \epsilon }}\right)^{2}\right)^{1/2}+1\right]\right\rbrace ^{1/2}}}={\frac {\left\lbrace \left[\left(1+\left({1 \over {\rho \omega \epsilon }}\right)^{2}\right)^{1/2}+1\right]\right\rbrace ^{1/2}}{\left\lbrace \left[\left(1+\left({1 \over {\rho \omega \epsilon }}\right)^{2}\right)-1\right]\right\rbrace ^{1/2}}}={\frac {\left\lbrace \left[\left(1+\left({1 \over {\rho \omega \epsilon }}\right)^{2}\right)^{1/2}+1\right]\right\rbrace ^{1/2}}{\left({1 \over {\rho \omega \epsilon }}\right)}}$

${\frac {\left\lbrace \left[\left(1+\left({1 \over {\rho \omega \epsilon }}\right)^{2}\right)^{1/2}+1\right]\right\rbrace ^{1/2}}{\left({1 \over {\rho \omega \epsilon }}\right)}}={\left[\left((\rho \omega \epsilon )^{2}+1\right)^{1/2}+(\rho \omega \epsilon )^{2}\right]^{1/2}}$ (wrong!)

Correct (I think):

$={\left[\left((\rho \omega \epsilon )^{2}+1\right)^{1/2}+(\rho \omega \epsilon )\right]^{1/2}}(\rho \omega \epsilon )^{1/2}$

I think the steps before are probably obvious. Constant314 (talk) 14:54, 13 April 2018 (UTC)

Yes, great! You made one typo and I corrected it ABOVE (with your permission!). So I hope that A.d.vannes is reading this (since you're not proposing it be included on Wikipedia, for the reasons already cited, I assume). Thanks, Interferometrist (talk) 17:00, 13 April 2018 (UTC)

The steps are obvious. Multiplying by one with the 'conjugate'-like term is nice, however. Thank you. A.d.vannes (talk) 08:47, 14 April 2018 (UTC)

@Constant314: Still a formatting error I fixed above, but still a small math error I (hopefully!) got right on the next line, please check! .Interferometrist (talk) 22:32, 17 April 2018 (UTC)

Evanescent wave is now Evanescent field

The article contains many instances of wave that need to be changed to field. It is more complicated than just substituting field for wave so there is a lot of work. If I had realized that, I might not have requested the change.Constant314 (talk) 14:18, 25 October 2015 (UTC)

=== you mention below about how evanescent fields oscillate - does that mean they propagate to nothingness perpendicular to the surface, or paralel, or not at all?

"That's not exactly true. You're thinking of a fully standing wave which happens when a wave (on a transmission line or a plane wave in space) is fully reflected. When the reflection is partial there is incomplete cancellation and the field has a general "motion" in the direction of the stronger component. Also, even with perfect reflection of a plane wave at an angle, you get "motion" of the standing wave in the transverse direction. I'm not sure why this is important though. Interferometrist (talk) 18:01, 17 October 2015 (UTC)" — Preceding unsigned comment added by 2600:1700:846A:780:6D24:C44E:7154:E4DA (talk)

Hi, I'm not sure I understand your question but I'll answer quickly. If you're interested in helping with Wikipedia, you should sign up with a username and it would be easier to communicate as you'd have your own talk page, whereas I have no way of even knowing if you're reading this.

As far as I am concerned, anything that propagates is a wave and anything that is bound to a surface DUE TO fields under or at that surface caused externally is not. We are only talking about alternating fields, so yes they oscillate but spatially they fall off exponentially. NOW, a travelling wave in an absorbing medium also does that, but for a different reason, and I call it a wave nonetheless. The distinction in my parlance has to do with the fact in that case the wave propagates to point B due to fields at point A in the same medium, rather than a field tailing from those in a different medium. But that's just linguistics. For examples of evanescent fields, read up on the fields beyond TIR or outside of a waveguide (the cladding of an optical fiber for instance), contrast these with any wave that is indefinitely self-sustaining (or at least would be if losses were removed). I hope that helps. Interferometrist (talk) 22:51, 2 December 2020 (UTC)

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Magnetic free Poynting vector

Hello ! I tried two times to add here the idea of a magnetic free Poynting vector useful, according cited authors, in quasi-static conditions. The contribution was deleted twice mainly because such a vector is not a relativistic invariant. May be, I should have started by a reference to the fact that Quasi-electrostatics and Quasi-magnetostatics can be shown to be Galinean approximations of Maxwell equations (see for instance Levy-Lebond Galinean Electromagnetism). As a result none of energy density flux defined in these domains would be relativistic invariant. Nevertheless they can be useful tools in their respective domains, in the same way that Kepler laws are useful without being relativistic. — Preceding unsigned comment added by Henri BONDAR (talk • contribs) 11:19, 22 January 2016 (UTC)

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Wave

Thanks for working on the Wave article. Feel free to respond here if you need more discussion than what we're doing via edit summaries. Dicklyon (talk) 22:13, 13 August 2020 (UTC)

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Thanks for making the halo antenna article more succinct!

Hello Interferometrist:

Thank you for your good emendations to the halo antenna article. I especially appreciate your skill at shortening the article without loosing substance, whereas I tend to put in too much. However there are a couple of things that I have issues with: One is already changed; the other will be in a few days.

I have reverted some of your more conservative reduction of the range of frequencies a small transmitting loop is capable of: Neither the upper nor the lower bound is "crisp"; both are based on what's tolerable, and what's feasible. The upper frequency limit at circumference = ⁠1/3⁠ λ comes from the difficulty tuning out the high reactances just above the frequency that gives circ. = 0.3 λ. The widely repeated ⁠1/4⁠ λ limit is a practical goal that most freshman antenna-builders can manage.

The lower frequency bound for small transmitting antennas is a matter of personal taste, and a consequence of skillful loop construction (or not). If you're a klutz, like me, you'll have to use a higher frequency limit around ⁠1/8⁠λ, since conductor resistance losses from poor construction will overwhelm the skimpy radiation resistance. If you can build or buy a very low-loss loop, and can tolerate the low R_R (and exceptionally dangerous voltages) you might be satisfied with performance at ⁠1/10⁠ λ, or push down to ⁠1/20⁠ λ, just to show off and / or see what it can do. At that extreme, of course, it might be the feedline that's successfully radiating, rather than the loop.

The point of this is that the bounds are subjective, based on what's practical for antenna building. As with all things in amateur radio, especially since some antenna designs and their names are now more than 100 years old, including small loops (think of Hertz's first experiments), the names people use now to describe antennas and radio parts are a mishmash of old and new, and strict and loose. Your pointed comments in your edit descriptions, though often valid, suggest that you think that the terms are or should be sharply defined. Some are (e.g. "balun" and "whip antenna"). Many are decidedly not precise (like "shortwave", "Windom antenna", "Marconi antenna", or "flat top"). (Another example: there is no frequency on the 40-meter band where the wavelength is actually 40 meters; likewise the 60, 20, 17, 15, & 10 m bands.) (And let us note that the so-called "UHF" (PL‑259 & SO‑239) connectors are not usable (with 50 Ω cable) on UHF or even upper VHF.)

As far as the definition of "small" loop, some (excessively) fussy writers declare that only ⁠1/10⁠ λ is sufficiently small, since they demand that for a loop to be a "small" loop, the current must be more nearly uniform than the current through a ⁠1/4⁠ λ loop, which is too uneven for formulas based on uniform current to be accurate. But please note: That is a subjective standard: The standard is based on how much error the objector finds tolerable in the impedance and radiation formula results. Even the dissatisfaction with a non-uniform current is based on the larger antenna not matching well the analytic assumption of uniform current. In essence it's as absurd as saying "Your feet are too big for your shoes." A better, less simple approximation is required (truncated sinusoidal, actually) for a ⁠1/4⁠ λ loop, rather than defining it off of the playing field for performance not conforming to the approximation. I say, make bigger shoes, don't demand smaller feet!

So please, temper your enthusiasm for precise amateur radio terminology; under this topic, precision is in short supply – not nearly available enough to suffice for your enthusiasm – and a lot of precise statements are based on personal, and arbitrary choices. I want your edits to keep on coming. I think almost all of the changes you made are legit and improved the article, but I fear you'll be frustrated to the point of switching to physics or mathematics, where the terms are (mostly) strict and clear. Some of your criticisms I found quite valuable: Like your demands for citations. I am indeed the one who wrote the footnote about half-wave and quarter-wave loops being merely a matter of frequency, because I've done it. You were very right to call me up short for using my own authority, rather than bothering to find a citation. That's why it's going to take a week or two over Christmas, digging through my reference books & articles, before I put the footnote back.

And please note that the point I was trying to hammer home with the remark in the footnote is exactly what I'm worried annoys you: The terms in use (like "halo" and "small loop") are just not that precise, and often are clearly flawed under minute technical examination. The "halo" fails the acid test by blissfully transmitting at half its design frequency, with just a bit more capacitance across the breakpoint, or an inductor near the feedpoint. (A wide reactance-range antenna tuner and high-impedance feedline help a lot.) As far as I can tell, in many cases, there are no authorities who present or enforce strict definitions. (For English terms the nominees might be the U.K. IEE and the U.S. IEEE, but my take on their online dictionaries of terms is that they're being carefully non-committal, and just trying to explain the gist of common use. I tried to include a link to the IEE glossary, but have lost track of it.)

Regards from soggy Oregon/
Dr. Tom Lougheed (K7TLI)
Astro-Tom-ical (talk) 05:34, 23 December 2020 (UTC)

Some suggestions on the halo article

I appreciate many of the changes you have made. I also agree with much of what Dr. Tom has said. However, I have a few comments.

I think we have more than enough information about small transmitting loops in this halo article. There is a reasonably good article on the small transmitting loop, and we do not need to overdo the comparison in this article, except to mention that the halo is close to a half wave in circumference, while the small transmitting loop is considerably smaller and thus need a large tuning capacitor. Actually a small transmitting loop becomes a halo as its tuning capacitor becomes very small. Thus I do not see them as radically different since on becomes the other in the limiting case. Of course as this limit is approached the pattern changes radically. So it really is true that definitions became a bit squishy.

As to the high voltage on the small transmitting loop, one of the serious design factors in a small loop is the voltage rating of the tuning capacitor. Voltages across it can be many thousands of volts. Most of the recent designs for small transmitting loops are fed with a small loop placed just across from the tuning capacitor. If properly sized, the feed loop has 50 ohms input impedance and no excessively high voltages anywhere near it. It is possible to feed a small transmitting loop by putting a relatively large capacitor in series with the smaller high voltage capacitor. In that case indeed there would be high voltage near the input terminals, but I haven't seen such a feed method used in practical antenna designs.(possibly because of the danger). Actually, since the current in the loop is taken to be nearly uniform, at least at the lower frequencies, a "matching" capacitor could be inserted anywhere, even on the opposite side from the tuning cap. But again, I haven't seen this done, since the loop feed method works so well. Or perhaps, I have misunderstood what you are saying about the matching method and high voltage points.

On very small receiving loops, a good rule of thumb is to make the diameter 1 meter or so regardless of frequency to guarentee that one hears "antenna noise". That is to say, the loop will pick up enough signal (or noise) to swamp the noise figure of the receiver input. However, many AM radios were built in the old days with considerably smaller loops. This was acceptable in most locations because man made noise was considerably more than the noise floor in a very quiet location, which was used to come up with the rule of thumb of 1 meter. If we take that rule at 540 KHz a 3.14 meter circumference divided by 555 meters wavelength is .0056 of a wavelength. Using the dimensions of the loops found in many radios of the era the number would be about .002 wavelength. Thus I don't think that the limiting value of 1/100 of a wavelength for small receiving loops is correct as mentioned in the article on loop antennas. The figure of 1/16 of a wavelength is very far off. Is it possible that you have in mind single turn receiving loops? Of course the small receiving loops consist of multiple turns. And in the old AM receivers,(and long wave direction finders) the multi-turn loop had a parallel capacitor and fed directly into the grid of the first tube as a high voltage, high Z source. JNRSTANLEY (talk) 13:00, 29 December 2020 (UTC)

Hi, I also copied the above to Talk:Halo antenna in order that anyone else (?) editing or interested in that page would be looking there, not here, and to have it all in one place. So please look there for further discussion! Interferometrist (talk) 07:39, 30 December 2020 (UTC)

Skin depth in poor conductors

@Interferometrist: Greetings. We have collaborated before in the skin effect article on the formula for skin depth when the conductivity is low. I’d like to have a dialog about that, if you are interested. Sorry to bother you, but you are the only editor that I know that could or would look at the math.

I have concluded that the formula is less than useful in that it does not take account of dielectric loss. There are missing terms that involve resistivity multiplied by dielectric loss tangent. In a good conductor with low resistivity, those terms are insignificant. But when the resistivity is high, they become dominant. So much so that the conclusions about the asymptotic minimum depth in silicon is, I believe, incorrect. Constant314 (talk) 22:38, 14 March 2021 (UTC)

Hi @Constant314, and sorry for the late reply! I just haven't had time lately to devote to Wikipedia (yes I know everyone else is bored while stuck at home, but me the opposite!).

I do remember editing that, and if it's at all wrong then please remove or (as I know you will!) improve it. Someone else put in the original statement about an asymptotic skin depth as frequency increases, being important for poor conductors. So I threw in some numbers for that example but obviously didn't consider everything about silicon that maybe you have (but I take it you are not questioning that there is such a minimum skin depth that applies in other cases following the equation written to that effect?). In fact I got involved in an agreed-on equation for the skin depth "in general" consisting of two correction factors, neither of which I thought would ever be important in the cases where skin depth is ever discussed, conductive metals at RF or mains frequencies. If one asked me about the penetration at some greater frequency (say in the IR) in silicon or something, I would quit thinking about currents and consider the index of refraction and the imaginary part in particular which gives you the decay coefficient. So come to think of it, silicon is opaque in the visible, obviously a much smaller "skin depth" than the supposed limit! But do go ahead and edit as needed and dispense with what I wrote - especially if it's plain wrong!

Best wishes, Interferometrist (talk) 23:37, 27 March 2021 (UTC)

And thinking about it more, I realize that wave propagation into a material is a more complex analysis than skin depth which is based on a simple model of magnetic field cancellation by eddy currents, calculated for a given finite conductivity. Which obviously doesn't take into account polarization currents in a dielectric. Or therefore the resulting power of an EM wave lost due to resistance to that current (dielectric loss) so that alone increases or will dominate (especially in very poor conductors, as I can see!) over field losses due eddy currents. So again, I think the text should emphasize the leading factor (not the two corrections) and that it's a concept useful for rather or very good conductors. It's not the entire story, just a good model used in certain fields, engineering really, not science. Interferometrist (talk) 01:03, 28 March 2021 (UTC)

Hi. @Interferometrist, thanks for the response. I did not want to dump a bunch of math on you if you were not interested. It is straight forward, but tedious, to insert the complex forms of permittivity and permeability into the formula for the wave number and gather the terms. I don’t think I made any mistakes, but it happens. Anyway, with silicon it appears that the skin depth goes down inversely with the square root of frequency, then levels off and then when dielectric loss becomes important the skin depth continues to decline inversely to frequency. So, I think that the statement that there is an asymptotic depth is wrong, but the conclusion that skin depth can be ignored is probably still correct. I’ll give some more thought to fixing it. It is not likely to cause any harm as is.

I’m glad that you are finding plenty to keep you distracted. Constant314 (talk) 01:05, 28 March 2021 (UTC)

And also come to think of it, I'm pretty sure I did NOT introduce the silicon example, which was rather farfetched anyway but I did edit that section and left it so I'm responsible anyway. Is there not some COMMON poor conductor that would make a useful example, with realistic/understandable results? Interferometrist (talk) 01:12, 28 March 2021 (UTC)

All poor conductors that I can think of I would expect to have some dielectric loss. I'll look around. Maybe I can change out silicon for something else. If you want to look at some math, have a look at my sandbox User:Constant314/sandbox.

The simplest that I can get it down to (by assuming no magnetic loss) is this

$\delta ={\sqrt {\frac {2\rho }{\omega \mu ^{'}}}}{\frac {\sqrt {{\sqrt {1+2\rho \omega \epsilon ^{'}\tan \delta _{e}+{(\rho \omega \epsilon ^{'})}^{2}}}+\rho \omega \epsilon ^{'}}}{1+\rho \omega \epsilon ^{'}\tan \delta _{e}}}$

The primed terms indicate the real part of the quantity.

You can see that if $\tan \delta _{e}$ is zero, that this formula reduces to the formula in the article.

At high frequency becomes this.

$\delta ={\frac {2\rho }{1+\rho \omega \epsilon ^{'}\tan \delta _{e}}}{\sqrt {\frac {\epsilon ^{'}}{\mu ^{'}}}}$

So, if the frequency is high, but not too high, there is a plateau. But if the frequency keeps going up, that $\rho \omega \epsilon ^{'}\tan \delta _{e}$ term dominates.

Constant314 (talk) 02:09, 28 March 2021 (UTC)

Radiansphere and Effective Aperture

Hello Interferometrist,

Regarding your edits of 16:54, 25 June 2021‎, your comment on "‎Derivation of aperture of an isotropic antenna from the radiansphere definition:" was that this was "Invalid (or actually, missing) derivation. Radiansphere is arbitrarily defined to match the already-known average crosss-section of an antenna to be λ^2 / 4π, so this is basically a circular argument."

Radiansphere in Wheeler's work is not "defined to match the already known cross-section of an antenna to be λ^2 / 4π" as you claim. It is defined to be the transition point between the radiative near field and the reactive near field of a small antenna, at which distance the three terms of the field are equal in magnitude. Its radius is one radianlength, or lambda/2pi, and its cross sectional area is 1 radiancircle or PI*R^2. The effective aperture using his definition is the product of the radiancircle with its radius set to 1 radianlength, revealing that the effective aperture is simply the projected area of the radiansphere. By this definition, within a radiansphere, fields within this region will interact with the antenna through inductive or capacitive coupling. Fields outside of this region do not couple to the antenna. The average cross section of an antenna (2D^2/lambda) relates to the far field zone onset (known as the fraunhofer distance), but Wheeler's definition refers to the transition between the reactive near field and radiative near field, occurring at lambda/2pi, and thus does not relate to the antenna cross section at all. The derivation starts from Wheeler's work and leads directly to the effective aperture expression. I like many of the other changes you have made, but I think you have missed the opportunity to convey the simplicity of effective aperture in terms of the reactive near field distance of 1 radianlength, in which fields actually couple to the antenna, and the resulting cross section of the sphere based on it. Wheeler's work is powerful and insightful, and effective aperture naturally falls out of it in simplicity. It isn't circular, and startlingly simple if one understands the meaning of the reactive near field. For this to be circular, Wheeler would have had to start his derivation of radiansphere from the average cross section of an antenna effective aperture definition λ^2 / 4π which he does not. It should be noted Wheeler's definitions are for a small antenna with maximum dimension less than 1 radianlength, and applies to ideal isotropic antenna whose geometry is not defined but may be considered to be small. If you think repeating Wheeler's paper derivation for the 1 radianlength definition of the reactive near field distance (where capacitive and inductive coupling occur and hence the antenna has aperture) is appropriate, we can add it. Also, in general, I believe neglecting the work of Wheeler, Harrington, and Chu in this topic is a major omission.

make_waves (talk) 06:59, 11 July 2021 (UTC)

Loop antenna

Hello, I understand if you are tired of talking about loop antennas. I don’t know if you saw my last comment and figure, but I believe it visually illustrates the point that I was trying to make about the loop antenna and the E-field. I hope that you take a look at it, even if you do not want to continue the conversation. Constant314 (talk) 00:40, 22 October 2021 (UTC)

@Constant314: Hi, thank you for your message. Indeed I had lost interest in "continuing the 'discussion'" and realized I should have stopped with a completely repetitive exchange much much earlier and devote my time to something useful. I considered including a small section in the article explicitly stating, in equations, the response of the infinitesimal loop to a radio wave (or not wave). But I realized that I would have been doing it more to satisfy (which it wouldn't!) a few editors on the talk page rather than the 100's of Wikipedia readers who would not find a similar equation (I believe) in the page of ANY antenna article even including the Hertzian dipole. What's more, since it would be beyond anything I saw written compactly in any antenna book, I'm sure someone would mark it OR, and indeed I'm astounded to see that even Faraday's law of induction has been marked CN when it appears on this page as if it applies in all cases except where you call the wire loop an "antenna!"

Yes I understand your diagram and don't disagree with your rationale or the clear fact that you can represent the loop's response to a radio wave from a specified direction only in terms of the wave's E field with no regard to its H field, just as you can (more usefully!) only in terms of H (vector) with no regard to E (and no regard to the direction of the wave, or if there is a wave). When you start talking about which field causes which, then the discussion inevitably degenerates and arguments cannot be "won" because their subject is invalid. But from an engineering standpoint (which Hddharvey dismisses as a "colloquialism") when you have more than one equally valid (thus equivalent) way to solve something, you use the simpler equation which of course is V=N×d(B⋅A)/dt. Moreover, using that formulation you can then count as contributing to B the result of a current in the loop and proceed to find, for instance, the current induced when the loop is shorted in which case the E field around the loop is zero (it's shorted!) and thus doesn't tell you anything, or more generally for any specified electrical load. Again, I could write that into the article but it would be marked OR and CN and would mainly be there to make a point to a few editors rather than the typical reader. So yes, I'm taking a break from this page right now and will look at it in the future after this "debate" has been cleared from my mind and I can take a fresh look at what is there, what should be there, and anything that is wrong. Interferometrist (talk) 16:26, 25 October 2021 (UTC)

The CN is referring to the claim about "magnetic loop" terminology and not Faraday's law of induction per se. I apologise that it was not clear. I have adjusted the positioning of the template to try to clarify that. Hddharvey (talk) 05:28, 28 October 2021 (UTC)

@Hddharvey: Fair enough. I hadn't even known you were the one who placed that CN, but with your explanation I understand that that portion of my complaint was invalid. Still, I can't help but noticing that the expression for V in terms of d(total flux)/dt doesn't contain any other terms having to do with E, which was my point all along.Interferometrist (talk) 21:45, 28 October 2021 (UTC)

@Interferometrist: I agree that Faraday's flux rule ${\mathcal {E}}=-N\,d\Phi _{B}/dt$ gives a simple expression for the emf in terms of flux. However, the emf along a path ${\mathcal {P}}$ is defined as:

${\mathcal {E}}=\int _{\mathcal {P}}({\text{Force per charge}})\cdot \mathrm {d} {\boldsymbol {\ell }}=\int _{\mathcal {P}}(\mathbf {E} +\mathbf {v} \times \mathbf {B} )\cdot \mathrm {d} {\boldsymbol {\ell }}$

If the antenna is stationary and not deforming, then this just reduces to the line integral of E. So that's where the E is hiding. (Even if the conductor is stationary, there will be a magnetic force if there is current flowing, since the charges will be moving - however, this magnetic force will usually be perpendicular to the path ${\mathcal {P}}$, so has no contribution to the integral for sane choices of a path ${\mathcal {P}}$.) In a sense, the line integral of E is what Faraday's flux rule is trying to calculate. Given a known (rate of change of) magnetic flux, we can easily calculate the electromotive force (in this case, only due to E) along the small loop - which is what will determine the voltage we read at the terminals. If the small loop is moving or deforming, then the emf that we're trying to calculate is both due to E and B. Again I have no absolutely no objections to:

• "A small loops response is determined by the magnetic flux/field"
• "A small loops response is easily calculated from the magnetic flux/field"
• "A small loop detects the magnetic flux/field"

these are correct statements and I do not regard them as colloquialisms. Thinking this way is common since it's often more useful to measure $\mathbf {B}$ than to measure $\nabla \times \mathbf {E}$. What I do regard as more colloquial language is:

• "A small loop rejects/ignores/is insensitive to the electric field"

This language often makes sense since we often ignore toroidal E and consider it a magnetic phenomenon. However, the only E present in an electromagnetic wave is toroidal E, so I think it makes less sense to pretend that part of the electric field doesn't exist when talking about antennas or waves. At the least, one should be more specific about what parts of the electric field are being rejected - since it's clearly not the "wavy" part of it. Hddharvey (talk) 04:05, 29 October 2021 (UTC)

"Matching to an antenna array" section of the Antenna "Antenna Array" article

Dear Interferometrist, I like your comment of 24 September 2021. In fact, I have spent a lot of time trying to explain to antenna designers that: what is often referred to as "output impedance" of a single port transmitter is only the complex conjugate of the load impedance for which the amplifier was designed. In fact, the output of most PAs is not linear at all, so that discussing the actual impedance of their output is risky. Hence, if an amplifier output is labeled 50 Ohms, it typically does not mean that an impedance presented by the output is close to 50 Ohms. Nevertheless, I would like to discuss your comment. Being not an experienced contributor to Wikipedia, I do not know how to do this. I hope that this message will reach you, somehow. Regards, FreddyOfMaule — Preceding unsigned comment added by FreddyOfMaule (talk • contribs) 07:36, 29 October 2021 (UTC)

I second these remarks by Freddy. This whole section "Matching to an antenna array" is not helpful and should be deleted. The array should present the load value, (typically 50 ohms) for which the transmitter is designed It has no relationship to the output Z of the amplifier. JNRSTANLEY (talk) 11:24, 29 October 2021 (UTC)

@FreddyOfMaule: - thanks for your remarks (if you're seeing this!). The best place to discuss this is on the talk page of the antenna array article, and/or to just go ahead and edit the page accordingly. Also, when you finish a comment on a talk page, type four tildes "~" ×4 (I can't write it out here 4 times or it would become a command!) to create your signature and time of edit.

But where you are sure that a statement in a Wikipedia article is wrong, or could be made clearer, then go ahead and edit it to make it correct. The worst that can happen is someone will disagree and you'll have to convince them or supply references supporting your change. If you are not sure enough about what to write, then express your reservations on the talk page Talk:Antenna_array. I haven't been active myself with that page but saw the invalid text and marked it so someone else (like you) could fix it! But feel free to ask me for further advice or knowledge, or if needed to support you in that effort should you encounter resistance :-) Interferometrist (talk) 22:01, 29 October 2021 (UTC)

@Interferometrist: - Thank you for your detailed reply. I have added a paragraph introducing a background of matching metrics, which I think covers adequately your concern. The main issue here is that many antenna array designers still optimize multiport antenna arrays using only the $|S_{ii}|$ over the bandwidth of interest. The plot at the end of the "Matching to an antenna array" section, and the corresponding explanations clarify why metrics such as $|F_{M}|$ or $|F_{R}|$ are much better, though they are of course subject to the limitations explained in the added paragraph. I wish to ask you a question: do you have (a) good reference(s) that explain(s) the typical characteristics of RF PA outputs, for different PA classes (e.g., class A, class AB, class C, class F, etc) and different amplifying devices (e.g., bipolar transistor, RF mosfet, RF triode, RF tetrode, etc)? In this area, I have only some application notes about amplifying device data sheets, and my own experience, but I could use a good reference relating to RF PAs. Regards, FreddyOfMaule (F5OYE).FreddyOfMaule (talk) 11:55, 30 October 2021 (UTC)

@FreddyOfMaule: Hi. Good edits overall. However, I notice that you are writing in text-book voice or academic voice instead of encyclopedic voice. I made the same mistake when I started editing. You may want to revoice your edits.

I thought that we agreed that the power amp is typically not an LTI generator. It seems off-topic to spent so much effort on matching an LTI generator. We should be having this discussion on Talk:Antenna array. Please consider moving the conversation to there. Constant314 (talk) 13:38, 30 October 2021 (UTC)

@FreddyOfMaule: Hi, I don't have too much time and only skimmed your reworked section on matching (as I gather it) M transmitters to N antenna elements (I expected M=1, but then you mention a MIMO system) using a M+N port network, which I guess is within my expertise on linear systems though my original objection didn't so much have to do with linear networks as simply what impedance a transmitter should see and why. Now thanks for your questions but I have to say that even though I am willing to approach the subject, my only practical experience in radio transmitters is from long ago (before they had MOSFETs!). It isn't clear how much your remarks and edits are based on practical experience and industry practices or just principles of electronic circuitry. I'm perfectly willing to read what you have to say about connecting transmitters to antennas but (again, having only skimmed it) I'd have to say that what you wrote had me rather lost, partly as the quantities and systems you had in mind weren't laid out explicitly. And I cringed when I read "where Tmn is the least element of the set of the values...." which runs counter to most all linear analysis in which you avoid non-linear operators such as "least element of." Unless it was a practical rule-of-thumb sort of measure, but that wasn't how the preceding discussion appeared. Although you must have worked hard to produce this text, I think it is either too sparse (in terms of laying the foundations for the treatment) or more likely just so beyond the level of the first half of the article which had to do with basic descriptions and concepts, that one would get lost when they get to your section unless they were already very familiar with the subject and just wanted to read about impedance matching using N-port networks (which I already find rather daunting when N>2).

I wouldn't have exactly complained that you are using "text-book voice or academic voice" as Constant314 mentioned (I wonder if he thinks I do?) but stating your intention to supply information "which can be used to design an antenna array" is the wrong way to start because Wikipedia is supposed to be a source of knowledge and not a "how-to" manual -- perhaps this is part of what Constant314 meant. But that's just the way it was introduced, and nothing that you wrote (if correct) is unacceptable but I wonder if it shouldn't be (with a change of emphasis) rather turned into a section in the Impedance matching page which currently only discusses the usual case of connecting ONE source to ONE load using a 2-port. It would seem that the design of an N-port for feeding an array of antennas would need to at least mention and hopefully quantify the needs for relative phasing (and amplitude control) whereas your treatment seemed to be so general that this was just understood, and I'd expect that in general (unless the array elements are excessively spaced) you'd need to know the mutual impedance (or other) matrix governing the antennas' near-field interaction. Maybe that's what you were questioning where you started with "If there is no interaction between the port of a multiport antenna array...." which wasn't clear and at which point I got lost (I hadn't seen a clear model setup for which these words have a clear meaning).

But listen, this all is way beyond what I was originally objecting to, which is to say that a transmitter with a specified 50 ohm load, does in general NOT have a 50 ohm source impedance nor need it (unlike reception at VHF+ where you WOULD want maximum power transfer to the actual input impedance of the receiver). You dealt with this saying " In fact, many transmitter outputs are not linear at all, so that discussing their actual impedance is risky" though I would have gone further and said "irrelevant" rather than "risky." I was more just pointing out, what would be obvious to anyone with basic electronics knowledge, that just because my house wiring presents 230v with an internal impedance of 1 ohm (when you draw N amps, the line voltage drops to 230-N), you DON'T want to "maximize your power transfer" by plugging in a 1 ohm load! Or as stated in the Impedance matching page "Audio [power] amplifiers typically do not match impedances, but provide an output impedance that is lower than the load impedance (such as < 0.1 ohm..)" and which could have gone on to say that of course you don't take advantage of that by building a .1 ohm speaker, which WOULD work and be linear (up to a certain volume level!) but NOT efficient (you'd be burning up much more power in the amp than supplied to the load) or desirable (a voltage-source amplifier with an internal impedance << the speaker impedance is desirable for "damping" the speaker's natural resonance). Really, THAT is all I was trying to point out. You took it much much further! But again, although I assume what you wrote is accurate, if it is difficult (or impossible!) for me to understand then I doubt many readers will do a lot better with it. Remember, the most important thing in communication isn't what you say but what the reader hears.Interferometrist (talk) 19:22, 1 November 2021 (UTC)

@Interferometrist: - Thank you for your comments. Your last sentence was so convincing that I completely rewrote the beginning of the "Matching to a multiport antenna array" section, before dinner. Could you please forget the previous version, as well as everything we discussed, and read it with a fresh and open mind. I look forward to read your comments. Regards, FreddyOfMaule (F5OYE).FreddyOfMaule (talk) 17:54, 3 November 2021 (UTC)

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Waste

Re this: A waste of ink, I don't know, but most likely a waste of electrons. And of photons . I replied, carefully avoiding going technical, as that would go nowhere. - DVdm (talk) 00:17, 11 December 2021 (UTC)

@DVdm: Listen, I overreacted. My automatic reaction to shutting down discussion is always negative, and even if someone's contribution to that discussion is pointless or unproductive, there is little actual harm in just retaining it compared to the potential harm of selectively ignoring valid concerns. Now it's clear that the paper he pointed to does not represent established physics nor even a significant school of thought, so it doesn't merit any inclusion in Wikipedia. But what I read initially was that the coverage of the photon was too disconnected from the EM wave it's associated with, but this isn't too surprising given that wave-particle duality is not a resolved issue in physics, at least from the philosophical standpoint. Looking through the article again, I don't see anything wrong with it, and I'm sorry for getting so hot under the collar about the matter. Interferometrist (talk) 10:21, 11 December 2021 (UTC)

@Interferometrist: No worries. But note that in the message that I had removed ([2]), they did not point to a paper: [3]. The edit being nonsense and the absence of any kind of source prompted my removal. In the next edit ([4]) someone else pointed to some paper, so I did not remove that, and left it hanging there for anyone to comment, which is unlikely to happen, for the reasons you gave . Cheers. - DVdm (talk) 10:52, 11 December 2021 (UTC)

@DVdm:You see, I assumed from the time coincidence that those two edits were by the same person, using a different IP address (possibly intentionally but probably just from a different computer). Neither one was a registered user or even had edited before so the first edit wouldn't have popped up on the second's watchlist, say. But my (over-) reaction just had to do with the hastiness in which the first comment was reverted, and also not reading through and digesting it. I don't think that bad edits on a talk page (I see enough!) generally need to be removed, but better ignored. If the concern is a discussion breaking out over a fringe theory, then I'd break that off after it gets replied to at least once. But I won't press the point, and will try to remember not to edit until I've calmed down from something :-) Interferometrist (talk) 17:15, 12 December 2021 (UTC)

Good point! I should have checked that. - DVdm (talk) 17:19, 12 December 2021 (UTC)

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