User talk:Chetvorno

I will reply to comments below on this page, in order to keep the dialog in one place

I believe far field radiation corresponds to the radiation carried by what is usually referred to as electromagnetic radiation, light, radio waves etc. The reason it diminishes with 1/r in earth based situations is because we do not use spherical transmitters like the sun. Instead our transmitters generally have a straight axis. Therefore the radiation spreads like a cylindrical section rather than a spherical one so that changes in distance only impact one dimension rather than two . Our drawing in the two articles electromagnetic field and electromagnetic radiation is deficient because it shows waves which do not decrease with distance -- a case only applicable to photons.

The near field radiation deserves a good drawing as well. This radiation is caused mainly by the charges which move back and forth directly. Unlike far field the max velocity magnetic peak occurs at the same time as the minimum electrical field. So unlike the drawing the peaks are perfectly offset. It would have a drawing where the magnetic and the electric field peaks are offset and fall away much faster with distance.

Do you agree that the oscillating field drawing on both articles is incorrect showing either a laser or photons which do not diminish with 1/r? Bill field pulse (talk) 19:38, 28 January 2024 (UTC)[reply]

I agree with some of your points, but not that the drawing should be changed:

• The fields of electromagnetic waves sufficiently far from the source decrease with ${\displaystyle 1/r}$ not because they spread cylindrically, but because energy is conserved. In order for the total amount of power striking the surface of a spherical shell enclosing the source to be constant regardless of radius ${\displaystyle r}$ (a definition of conservation of radiated energy), the power density ${\displaystyle S}$ of the radiation must decrease with the inverse square ${\displaystyle 1/r^{2}}$ of the radius (because the area increases with the square of radius ${\displaystyle r^{2}}$). The power density is proportional to the square of the fields: ${\displaystyle S={\epsilon _{0}c \over 2}E_{p}^{2}}$ so far from the source the peak electric and magnetic fields of electromagnetic waves must decrease linearly, as ${\displaystyle 1/r}$ with distance from the source. They decrease at that rate whether on Earth or in space.
• The "near field radiation" is not radiation. The near fields of a radiating antenna or atom look pretty much like ordinary dipole electric and magnetic fields that are oscillating. You can see what the electric fields of a radiating dipole antenna look like in this gif animation I made. I agree it would be useful to have a drawing, preferably an animation, of the near fields.
• I agree far from the source the amplitude of the fields of an electromagnetic wave in free space decrease with ${\displaystyle 1/r}$, but in most of the far field the decrease is too small to see in a drawing. The drawing Onde electromagnetique.svg you are complaining about shows about 2 wavelengths of an electromagnetic wave. As an example, a radio wave from a 300 MHz television station has a wavelength of 1 meter. At a distance of 1 kilometer, the decrease in amplitude of the electric and magnetic field over the 2 wavelengths from one end of the drawing to the other would be only a factor of ${\displaystyle 1-{1000-2 \over 1000}=}$ 0.002 = 0.2%. This would be completely imperceptible in the drawing. A light beam from a red laser pointer has a wavelength of 650 nm. Ten centimeters from the laser the decrease factor would be only ${\displaystyle 1-{0.1-2*0.00000065 \over 0.1}=}$ 0.00013 = 0.013%. Far field radiation is usually approximated as a plane wave, a flat wavefront with the fields as constant amplitude sine waves similar to that in the drawing. I think it would be confusing to show a drawing of the fields with the amplitude decreasing, as that would only be an accurate representation of the fields near the source.

--Chetvorno^TALK 00:39, 30 January 2024 (UTC)[reply]

1) I see that my assumption that radiation amplitude and the power density at a point is wrong for the far field. Is it just a coincidence that amplitude and power density drop equally in the near field with r squared? So it is just like the sun where the total power in a thin spherical shell is constant and the radiation decreases with r squared. I imagined that maybe with a radio transmitter the geometry impacted the power drop. For example, with a laser the power drop is reduced because all the radiation is aligned and there is less diffusion with distance.

2) I completely agree that the near fields must be exactly like the normal fields around charges in this case oscillating. I also do not like to refer to these inner fields as "electromagnetic radiation" preferring to restrict that term to the radiation involving photons. However, do you agree that if a charge moves quickly the field is not infinitely rigid but establishes around the charge from the charge first on outward at the speed of light. This is still very, very rigid much more rigid than macro objects -- like a steel ball -- which establish around fixed points less quickly due to stretch of molecules etc. If you agree with this then around near light speed quarks the establishing from the center out is equivalent to "radiating" and EM field must be flexible and for quarks a field intensity wake must result.

If you have a good drawing of the near field I support you putting it in to the article. It would help people see that the field around charges is always there. I have not yet looked at your animation but I will look at it soon.

3) I think the drawing must say "looking far from the source". If we are looking at the first two 1 meter wavelengths then the second one should be half the amplitude of first one. I think a drawing was taken from a photon lecture. I like a slight change in amplitude rather than the appearance of constant amplitude. Bill field pulse (talk) 20:44, 30 January 2024 (UTC)[reply]

Your animation is excellent for the far field and better in some ways than the one we are using.

Your animation clearly shows a near spherical spread. I have seen others drawings where there is a frontal lobe of less than 45 degree spread and a smaller rearward lobe also less than 45 degrees. The radiation power in other directions was far lower in the practical examples I saw. I guess designers can direct the far field to minimize power waste depending where they want the most power to go. Bill field pulse (talk) 20:57, 30 January 2024 (UTC)[reply]

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Thanks for catching all my spelling errors--danger of late-night editing w/o LanguageTools turned on! DrKC MD (talk) 18:48, 6 April 2024 (UTC)[reply]

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All 95 addresses are mine. Even ones you marked as "not" here [1]. You don't understand that some ISPs rotate addressed more frequently and often reuse them. I was posting only on Tesla board , none of other contributions of the 2 ips with more contributions are mine. The IP was reused and someone else made contributions. For ip 95.168.116.19, the only edit that is mine is from 5th July. Even the edit on 26th May which is about Tesla isn't mine. For IP 95.168.120.122, the only edit that is mine is from 4th August. All other edits before and after that aren't mine. Ip got reused and assigned to other users. Bdw, this is often the problem with Check User. It sometimes misidentifies editors because 2 editors can be assigned the same IP. Croatia is small and there is significant chance that 2 Croatian editors on the same board will be assigned the same address. Look. It happened to me on ip 95.168.116.19. Someone posted Tesla related post on 27th May and on 5th July I got assigned the same Ip and I also posted Tesla related post. If we had accounts, CU would identify that as a proof of shocking, but it isn't. Anyways, all 95 ips are mine.

Other editors are ip 77 who did vote and done discussioning. Ip 5.39.134.145 who just put a vote, didn't discuss apart from posting one comment from 93.141.183.145, and later from ip 93 challanged the consensus. Ip 31.217.16.206 who just voted. Ip 72.139.121.219 who didn't vote , but posted a comment attaching Trimpos2.

So to summerize, we had 5 people posting from Ips. I don't think anyone is socking here, but you are free to open SPI 95.168.124.26 (talk) 11:54, 23 August 2024 (UTC)[reply]

Okay, thanks. There has been some sock activity on the Talk page during RfCs in past years, so the question sometimes comes up when IPs join the discussion. Is it okay if I move this conversation to Talk:Nikola Tesla/Nationality and ethnicity since it concerns the RfC? --Chetvorno^TALK 12:32, 23 August 2024 (UTC)[reply]

If you have a moment... could you check my edit to the Ground plane article? I found myself asking this specific question on SE because the Wp article implied that the reflector's connection quite simply didn't matter https://ham.stackexchange.com/questions/22968/ground-plane-connection-to-screen/22974 but there's a lot I'm unhappy about: the operating principle of a "no ground-plane" antenna e.g. magmount on a vehicle roof, the potential screening effect of a non-connected ground plane (could it be said to have any effect at all?) the difference between reflectors for a monopole and a yagi and so on: I've basically focussed on trying to make my edits safe, and a bit more use than the original.

Many thanks for your https://en.wikipedia.org/wiki/User:Chetvorno/work6#Radiation_pattern which I found most enlightening. MarkMLl (talk) 12:00, 15 September 2024 (UTC)[reply]

Thanks for asking me. I'll take a look. --Chetvorno^TALK 14:24, 15 September 2024 (UTC)[reply]

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TheWikiToby (talk) 05:08, 4 November 2024 (UTC)[reply]

Sorry I apologize. I was just asking for suggestions and did not realize this post would happen. Johnjbarton (talk) 06:23, 4 November 2024 (UTC)[reply]

No problem. --Chetvorno^TALK 18:16, 4 November 2024 (UTC)[reply]

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