Talk:Dipole antenna

message: Does the discussion of voltages in the Half-wave antenna section make any sense? It's not clear what the y-axis is in the :File:Dipole Antenna.svg graph, since potential difference is not well defined in a non-conservative field unless a path of integration is specified. Perhaps the intended path is a quarter-circle arc from the plane normal to, and through the centre of the dipole, to a point on the conducting element - but this is not stated. The statement: A standing wave on an element of length approximately λ/4 yields the greatest voltage differential is likewise unclear, and the sentence The larger the differential voltage, the greater the current between the elements. is perhaps a misunderstanding. I'm inclined to delete the voltage plot and any mention of voltages - or can somebody explain the intended meaning? --catslash (talk) 19:07, 25 December 2012 (UTC)
thread_title: Half-wave antenna: 'voltage distribution'

message: What is a billboard antenna?
When I click on "billboard antenna" in some other Wikipedia article,
I expect to go to an article that at least mentions the word "billboard".
Instead,
I end up here at the dipole antenna article,
which currently never mentions the word "billboard".
Is there maybe some other article that mentions "billboard antenna" that the redirect should go to instead, or does this article need to say a few words about "billboard antenna"?
--DavidCary (talk) 16:06, 14 May 2014 (UTC)
replies: text: See Reflective array antenna. Don't think it's a very common term though. --catslash (talk) 17:55, 14 May 2014 (UTC)
replies: text: I've changed the target of the Billboard antenna redirect page from Dipole antenna to Reflective array antenna. --catslash (talk) 18:04, 14 May 2014 (UTC)
replies: text:  Thank you, catslash. --DavidCary (talk) 15:59, 21 May 2014 (UTC)
thread_title:  Billboard antenna 

message: What is 5.12 dBi? What is a dBi. Is that decibels of the current ratio? If so, what is the numerator and what is the denominator?
WithGLEE (talk) 13:17, 9 October 2014 (UTC)
replies: text: As the article antenna gain makes clear in its introduction, dBi is decibels isotropic, the ratio of the signal power radiated by the dipole in the direction of its main lobe to the signal power produced by an isotropic antenna, which radiates equal signal strength in all directions.  It is the usual units used to express antenna gain. --ChetvornoTALK 19:50, 9 October 2014 (UTC)
replies: text: And I got the figure wrong.  The figure that was in the article, 5.12 dBi, was for a quarter-wave monopole, not a half-wave dipole, which is 2.16 dBi.  My bad. Thanks for catching that. --ChetvornoTALK 20:06, 9 October 2014 (UTC)
thread_title:  5.12 dBi perpendicular to the antenna axis, 

message: In the Hertzian Dipole equation for µH, why isn't the µ subscripted with 0? Jim Bowery (talk) 20:36, 23 August 2015 (UTC)
thread_title: Hertzian Dipole µH 

message: This is another term for a dipole antenna, and the Doublet antenna article is almost a stub. --ChetvornoTALK 06:50, 4 September 2015 (UTC)
replies: text: Done --ChetvornoTALK 22:18, 16 November 2015 (UTC)
thread_title:  Merge [[Doublet antenna]] here? 

message: There seems to be a focus on feeding the dipole in its center despite the IEEE definition of a dipole antenna not dictating such feed placement.  To wit...
"dipole antenna (antennas).  Any one of a class of antennas producing a radiation pattern approximating that of an elementary electric dipole.  Note: Common usage considers the dipole antenna to be a metal radiating structure which supports a line current distribution similar to that of a thin straight wire so energized that the current has a node only at each end.  Syn: doublet antenna."
An additional definition is found in the EIA/TIA-329-B...
"A dipole whose electrical length is half a wavelength and is formed by a straight metallic radiator, one-half wavelength long, whose diameter is small compared to its length, so energized that the current has two nodes, one at each end, producing maximum radiation in the plane normal to its axis."
The dipole is defined more by its function, than form.  It can be fed in the middle, end or anywhere in between and doesn't necessarily have to be two conductors as the text currently suggests (think J-pole).
crcwiki (talk) 17:22, 28 April 2016 (UTC)
thread_title:  Feedpoint not always in center. 

message: This article is woefully short of references and some sections have none.  Unless the points made are backed up with external references in a timely matter, I will begin marking problematic sections as Unreferenced or Refimprove.  I will do my part to search and insert references, but in the mean time viewers need to be made aware of the missing and required references. crcwiki (talk) 17:31, 28 April 2016 (UTC)
thread_title:  Severe lack of references to back up content 

message: ::You don't need metal to have a voltage. There is an electric field between the feedpoint, and at any point that field has an electric potential, measured in volts. I've said it before, now I'll say it again: part of what makes these images confusing is they don't specify precisely what they are illustrating. "Voltage" is anything measured in volts. Is that electric potential difference, and if so, relative to what reference? Electric field potential? 161.97.224.110 (talk) 14:19, 1 November 2020 (UTC)
replies: text: Well, I have to agree, the animation does not specify what the voltage reference point is, and this has been confusing readers.   Dipole antennas, like two wire transmission lines, are balanced loads.  From symmetry, the voltage is referred to a "center" potential midway between the voltage on the two feedline conductors. As you mentioned, there doesn't have to be an actual metal terminal at this potential.   You can imagine the AC voltage source at the bottom of the drawing split into two sources of half the voltage in series, and the wire connecting them grounded.  I'll add something to the caption about this. --ChetvornoTALK 21:18, 1 November 2020 (UTC)
replies: text:  I don't have any problem with the voltage in between the terminals being shown as a continuous slope from +V to -V, which implies a constant electric field in that region. Except to point out that that doesn't have to be the case, I could place a battery somewhere in the space between the antenna terminals and then the voltage between the positions of the two battery terminals would always be 1.5v DC, contrary to the diagram (and the antenna wouldn't be affected). But on the more general point raised by 161.97.224.110, one can NOT generally talk about a unique voltage in between point A and point B except in a DC (static) situation, or where the distance between A and B is much smaller than a wavelength as it indeed is in between the feedpoints, which is why you CAN talk about the voltage being fed to the antenna. But the only reason we can talk about the voltage along the antenna, is because we've agreed to conform to the Lorenz gauge. What is well defined at any point and time is the electric field E, but not how that is divided between the gradient of the scalar potential V and dA/dt due to the vector potential A. This is fixed by agreeing to the Lorenz gauge which stipulates the divergence of A in terms of V. You cannot just ask for a "reference point" for 0v and measure with a voltmeter (or scope) since what the meter measures depends on the geometry of the two leads (since we're talking about points not much closer than a wavelength, they can't take the same net path, like the ground clip right at the end of a scope probe). Pointing all this out in the article would be distracting and showing the voltage as if it were a unique measure without caveats is justified, but the full answer to 161.97.224.110 is that we have agreed to call a certain thing voltage in order to make the mathematics workable, and makes the antenna element look similar to a transmission line. Interferometrist (talk) 16:32, 2 November 2020 (UTC)
thread_title: Definition of "Voltage"

message: There is no information specifically relating to DAB.  — Preceding unsigned comment added by 84.93.82.80 (talk) 20:23, 7 October 2016 (UTC)
replies: text: Same kind of antennas work for DAB, just have to be suitable for the frequency. The bandwidth of DAB is not cause for concern. Graeme Bartlett (talk) 10:33, 16 August 2021 (UTC)
thread_title:  DAB - digital radio. 

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thread_title:  External links modified 

message: I've marked the sentence in the main article, topic heading above, as needing some verification the mildest way Wikipedia allows. The goal of compensating for the feedpoint inductance with antenna shortening has everything to do with maneuvering overall reactance of the antenna elements, not the velocity of propagation of the wire. I'd love to be proven wrong. If someone can provide a good reference from a college text book or engineering paper backing up the claim k = v/c, please do so. crcwiki (talk) 20:15, 30 October 2017 (UTC)
replies: text: Yes you are absolutely right: the wire itself propagates signals at the speed of light, period. With the end reflecting the signal and the wire radiating some of its energy, you get a voltage & current pattern from which this isn't clear, but that confusion is not a property of the wire. The only reason I haven't changed it is that I was overruled when I attempted to, though this was on the Antenna page (but I think I remember it happened on this page too) see Talk:Antenna (radio)/Archive 1#Invalid reference to "velocity factor" . But you are right, v<c is just wrong and should be fixed. Interferometrist (talk) 16:13, 4 June 2018 (UTC)
thread_title:  The adjustment factor k is equivalent to v/c. 

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thread_title:  External links modified 

message: I challenge the notion the longer antennas described in the "Dipole antennas of various lengths" section of the main article meet the definition of dipole antenna according to the IEEE-100-1984 and ANSI/EIA/TIA-329-B-1999. According to the definition a dipole antenna has no more than two current nodes. This rules out longer antennas with three or more current nodes that are more like long-wire than discrete dipole antennas.crcwiki (talk) 20:27, 1 March 2018 (UTC)
replies: text: I am not familiar with ANSI / EIA / TIA-329-B-1999. I have owned a copy of the IEEE standard dictionary (I don't recall which edition I had). The IEEE standards dictionary just copied definitions from various IEEE standards, out of context. Definitions that made sense in the context of a particular standard do not make sense outside of that context. I found the dictionary so unreliable that I threw it away. Jc3s5h (talk) 20:43, 1 March 2018 (UTC)

text: Yes I noticed IEEE-100-1984 is a compendium of definitions from other documents as well. The dipole definition comes from a predecessor of IEEE-145-1993 (that I have in front of me) that states the same definition as seen in another talk section above. IEEE-100 and now also IEEE-145 are currently our only primary references to the definition of a dipole from none other than the IEEE. The key part of the definition is "Any one of a class of antennas producing a radiation pattern approximating that of an elementary electric dipole." Any definition of a dipole that includes more than two current nodes violates this. If you have a primary reference that carries more weight than a standard from an organization catering precisely to work in electromagnetics, let's see them.crcwiki (talk) 21:26, 1 March 2018 (UTC)
replies: text: Yeah, that definition doesn't seem to be consistent with usage in most of the literature.  The antenna textbooks I've looked at include dipole antennas with more than 2 nodes; the 3/2 wave dipole, the 5/2 wave dipole, etc. , , , , although some technology encyclopedias seem to restrict the def to the half-wave dipole . --ChetvornoTALK 04:51, 1 April 2018 (UTC)
replies: text: I see the same as you in some of the literature. Most annoying is the text books rarely get around to actually defining what a dipole is. It's as if it is assumed. All that said, that IEEE definition just didn't come out of thin air. The contributors to IEEE-145 are likely antenna nerds from industry, research and universities. For them to come together on something like this definition of a dipole says a lot and carries some weight.crcwiki (talk) 15:08, 11 September 2018 (UTC)

text: I took that qualification out of the "definition." It is clearly wrong, whoever came up with it. Also wrong (marked CN) is saying that its radiation pattern must be similar to a short dipole. Maybe unqualified "dipole" doesn't have a concise definition. Interferometrist (talk) 18:44, 3 June 2018 (UTC)

text: Actually I see now I shouldn't have marked it CN since that there IS a citation. I'll invite someone else to deal with it. No definition is better than an incorrect one IMO. Interferometrist (talk) 18:48, 3 June 2018 (UTC)
replies: text:  Now I've reconsidered the objection to the portion of the "definition" about only 2 nodes. Indeed the resonant portion of the current that dominates the current along the antenna (especially if hi Q) is a standing wave in quadrature with the voltage pattern and crosses zero where the voltage is at a maximum (including at the ends). But that ignores the smaller out of phase (thus in phase with the voltage) component that is NOT zero at an intermediate node, so not technically a node. It occurred to me, that if there were really no current at some point along the element, then it wouldn't be possible for power to be electrically transferred to (and then radiated from) the outer portion of the element (just as the voltage doesn't go to zero at the feedpoint, just the component of voltage in quadrature with the current). Which doesn't completely settle the matter since it could be that the outer segment of the element doesn't radiate net power, just resonates (receiving power from the field), but I don't think that's the case. (Though I still wonder why this fine point is an important defining quality of the dipole.) So sorry, I edited without really being sure of what I was saying or thinking it through. Interferometrist (talk) 14:40, 4 June 2018 (UTC)
replies: text:  I will remove the citation needed then.crcwiki (talk) 15:08, 11 September 2018 (UTC)
thread_title:  Section: Dipole antennas of various lengths 

message: The article makes repeated use to the term "directive gain" which is a term I see rarely used elsewhere. The 1983 edition of the "Use of Standard Definitions of Terms for Antennas & Propagation": IEEE Std. 145 says:
"A substantive change included in this revision is the deprecation of the term directive gain and its replacement by the term directivity. This change brings this standard in line with common usage among antenna engineers and with other international standards, notably those of the International Electrotechnical Commission (IEC)."
Given the term "directive gain" was depreciated 36 years ago, it makes sense to use directivity instead of directive gain. The latest edition of the IEEE standard just says "directive gain: [Deprecated.] See: directivity."  Drkirkby (talk) 11:03, 28 December 2019 (UTC)
thread_title:  The term "directive gain" is repeatidly used, when directivity should be used instead 

message: This is kind of minor but Hertzian dipole should either have e^{-i \omega t} or e^{j \omega t} dependence by convention; e^{-i k r}/{r} in the dipole field formula (which comes from the Green function) indicates a converging (not diverging from the source) spherical wave as well. Classical Electrodynamics uses e^{-i \omega t} dependence as well, while Microwave Antenna Theory and Design, which the section cites, uses e^{j \omega t}. -Myxomatosis57 (talk) 21:27, 13 February 2020 (UTC)
thread_title:  Hertzian dipole time dependence 

message: I changed the chart to say "Resistive and reactive" rather than "Real and imaginary" and tried to make the comment "'j' is imaginary but reactive impedance is very real." Twice in a row the edit Published before I was ready. I don't know why, but I'm using a (rather clumsy) tablet and must have slurred a key - but I'm pretty sure I didn't hit the Enter button. Nor did I get a final look at what I was about to submit.
Could someone who knows how please submit this comment to the appropriate area, with the request "Please add more confirmation before a mobile device Publishes an edit".
And I have previously had the comment (not quite as bluntly put): "Mobile devices are crap; why are you using one". No, I think it should be possible to use a mobile device to make a minor edit and have it work the way you would expect.  203.220.159.238 (talk) 10:44, 8 October 2022 (UTC)
replies: text: Mobile devices are intended only for displaying advertising; you'd be better off using a Morse key for editing. --Wtshymanski (talk) 04:05, 17 October 2022 (UTC)
thread_title:  Two botched edits in a row.