This article is within the scope of WikiProject Physics, a collaborative effort to improve the coverage of Physics on Wikipedia. If you would like to participate, please visit the project page, where you can join the discussion and see a list of open tasks.
This article is within the scope of WikiProject Engineering, a collaborative effort to improve the coverage of engineering on Wikipedia. If you would like to participate, please visit the project page, where you can join the discussion and see a list of open tasks.
This article is part of WikiProject Electronics, an attempt to provide a standard approach to writing articles about electronics on Wikipedia. If you would like to participate, you can choose to edit the article attached to this page, or visit the project page, where you can join the project and see a list of open tasks. Leave messages at the project talk page
This article is within the scope of WikiProject Radio, a collaborative effort to improve the coverage of Radio-related subjects on Wikipedia. If you would like to participate, please visit the project page, where you can join the discussion and see a list of open tasks.
The line: "For computers, it's used the de facto standard Mcx cable." is not just bad english, but also probably very POV as there are lots of different cables used for antennas (The link points to a company called MCX Inc!).
The reference "Understanding electromagnetic fields and antenna radiation takes (almost) no math", by Ron Schmitt, EDN Magazine, March 2 2000 is linked to a host that is not related to the publisher (very useful article, by the way). Since the article is freely available on the EDN website, shouldn't the link be made to that page? Here is a direct link: http://www.edn.com/article/CA82250.html That page contains a link to the PDF version, which is the same as the one currently linked.
The June 2009 Antennas and Propagation article addresses only magnetic dipole antennas, but the conclusions apply to electric dipoles by the symmetry between electric and magnetic fields. It gives a tighter upper bound for loop antenna band widths. Magnetic materials help by lowering H for a given B.
Antenna converts electron movement into photons
Its not disruptive editing. There are hundreds of reliable sources that says the carrier of all EMF is the photon and that photons have dual wave particle properties as defined by the theory of quantum mechanics one of the most accepted models of subatomic physics. Thus, an antenna converts electron movements in the antenna into radio frequency photons. — Preceding unsigned comment added by 184.108.40.206 (talk) 14:22, 10 November 2013 (UTC)
Your addition will be confusing to people because antennas are not analyzed that way. Because the energy of the photons is so small the operation of an antenna is completely classical. The photons radiated by a television transmitter have an energy of 10-26 J and would be extremely difficult if not impossible to detect. We also don't describe a transformer's action by saying the primary and secondary exchange photons, and we don't describe how a hammer exerts force on a nail by saying it exchanges virtual photons with the nail, but of course it does. --ChetvornoTALK 14:58, 10 November 2013 (UTC)
All the sources I've ever seen describe radio frequency phenomena in terms of Maxwell's equations and approximations derived from them. If radio frequency phenomena are to be described in quantum mechanical terms, find a reliable secondary source that specifically discusses radio frequency antennas in quantum mechanical terms. I regard it as original research for a Wikipedia editor to attempt to apply quantum mechanical descriptions of phenomena at optical and shorter wavelengths to radio antennas. No doubt a qualified person (not a Wikipedia editor) could write such a description, but I don't know if it would turn out to be only theoretical or whether it would be experimentally verifiable. Jc3s5h (talk) 19:21, 10 November 2013 (UTC)
Reliable sources could be found; I found some. My point above is that it is not OR to describe the emission of radio waves by antennas using photons, it is misleading and UNDUE weight. Like all of classical physics, the functioning of antennas is at base quantum mechanical and could be described, as the IP suggested, in terms of the antenna's "energy levels" and radio photons. A process is called "classical" if the energy levels are too close together to measure, so the energy can be considered a continuous variable. Or equivalently if the individual photons are too low in energy to detect individually so the electromagnetic field can be considered continuous. From the Planck relation the energy of radio photons is between 10-21 and 10-26 J, far too low to measure, so an antenna operates completely classically. So describing the antenna as emitting photons is not technically untrue but is misleading, as it implies that antennas are not classical and are analyzed by quantum methods, like the emission spectra of atoms. --ChetvornoTALK 17:46, 22 November 2013 (UTC)
Interferometrist Could you please clarify "references to this usage IN PRACTICE", specially the last word. Thanks. Fgnievinski (talk) 01:53, 20 November 2014 (UTC)
I should have said "in common usage." We surely don't disagree about the physics, after all. Rather "Multipath" as a term of art has to do with the appearance of random/unpredictable/unanticipated paths for the wave in a communications link which cause certain well-known effects due to the additive reception of two waves having different propagation times. Now thinking about it further, this could well apply to the ground in certain instances where the lcoation of the ground is uncertain, such as driving around hills, or communications from an airplane (where the ground distance is varying and hills are moving with respect to the airplane). That has to do with propagation, not antennas. With antennas, a deterministic formula applies to the sum of two waves, not with regard to a particular receiver location, but to ALL receivers located in the direction theta. Thus the ground is part of the antenna which is why it is discussed under antennas. That deterministic effect (which could only be known about by inspecting the antenna at its location, not through signal fading, or intersymbol interference, the observable effects that the "Multipath" term applies to) is as much a part of the antenna as is a steel building an antenna is mounted next to which reflects an antenna's radiation pattern into a half space, or a corner reflector which concentrates the power into a quarter space, or the "reflector" of a Yagi antenna that re-emits radiation in a "second path" to cause predictable interference or a driven array with N paths for the same purpose. The term is not used in those cases, though of course these all involve multiple wave paths. That is because they are considered part of the antenna, and not part of the topography. This page is about the antenna system (thus including its ground) regardless of what happens to the wave after it leaves the vicinity of the antenna. The multipath page is about what happens to a wave between here and there without specific reference to the transmitting or receiving antennas (even though their radiation patterns and polarizations can very well affect the likelihood or magnitude of multipath effects). "Multipath" is considered a problem, whereas the predictable ground reflection (and other examples I gave) can be for the better or worse but are part of antenna design and implementation.
Now I have written more about this just for you (and a few editors watching this) whereas I'd rather spend my real time contributing to the encyclopedia and consider this exchange a nuisance, albeit required for cooperation. Now I would like YOU to cooperate and (appreciating the division I have delineated between the scope of the two pages) kindly revert your last edit. I don't appreciate having to revert something I know is inappropriate, and would like you to accept what I am pretty sure is the common usage of the term as opposed to the physical description of wave interference at the antenna itself. Thank you.Interferometrist (talk) 21:06, 20 November 2014 (UTC)
As an editor watching from the outside, I think you both make good points. On one hand it is true that the ground or ground plane near an antenna is part of the electrical circuit of an antenna and helps determine the radiation pattern. It is also true that especially in the near field, people don't talk about propagation paths; there is just the dynamics of the radiation field given the electrodynamic media and constraints imposed by antenna design and placement. Propagation paths and the eikonal approximation is for farther away. On the other hand, antennas don't exists in isolation and multipath propagation indisputably plays a role in some antenna designs. Antenna polarizations, heights and placements may all be optimized in part to avoid the problems of multipath interference. Ground bounce and hill/mountain bounce play a role in that optimization problem.
My opinion is that these two different roles for the ground should be clarified in this article. Treat the near field ground circuit in the effect of ground section and discuss associated antenna designs and radiation patterns. Move the antenna design considerations due to multipath propagation problems into a separate section or subsection and mention ground bounce as one of the possible paths producing interference. --Mark viking (talk) 01:37, 21 November 2014 (UTC)
In general I agree with Interferometrist that Multipath is not an appropriate place to merge ground reflection content. On the other hand I think the article is getting huge and bloated, and the Effect of ground section is pretty big, so I think with Fgnievinski that it should be moved somewhere. But I've only heard one side of the issue. Hey, Fgnievinski, can we hear your side of this? --ChetvornoTALK 02:37, 21 November 2014 (UTC)
@Chetvorno, Mark viking, and Interferometrist: 1. merge section into ground plane. 2. the ground/soil/earth may be considered multipath or not depending on whether it is part of the antenna design or not, i.e., whether ground reflections are desirable or undesirable ("unanticipated paths" as the Interferometrist calls it); I'll refer to these as primary and secondary meanings, respectively. 3. I've cited a handful of references referring to ground reflections as multipath reception, therefore the secondary meaning is indisputable. 4. primary and secondary has nothing to do with random or deterministic, e.g., ground multipath in L-band base stations is deterministic and undesirable. 4. I'm not sure if both primary and secondary meanings should be discussed in ground plane or only the primary meaning in ground plane and the secondary in multipath propagation -- your thoughts? Fgnievinski (talk) 05:05, 21 November 2014 (UTC)
Well no, not exactly. But thanks for all your comments and I believe we are approaching a consensus. I don't have time now to respond sufficiently but will try to do that soon (this weekend). In the meantime I will also make a few relevant edits. Let's avoid reverting/removing any material unless it's technically incorrect or completely out of place. We can discuss the proper framing of the material here, but it's not an emergency. Interferometrist (talk) 15:29, 21 November 2014 (UTC)
It seems to me a particular eyesore in this article is the Basic antenna models and Antenna gallery sections. The former section does not list "basic models", but merely some of the more widely used antennas; dipole, Yagi, random wire, horn, parabolic, and patch. This has huge holes: what about monopole antennas, array antennas, loop antennas, traveling wave antennas? I think the section should be rewritten to give a comprehensive overview of antenna types, organized under headings in some way, with individual antennas listed under each heading so readers can see where each fits in. --ChetvornoTALK 13:52, 22 June 2015 (UTC)
The other problem is with images. The images in both sections seem very haphazard, they have just collected over the years. A lot of them are not the best illustration of that antenna type. There's a lot of duplication, and gaps: types of antennas which are not shown. The images should be culled, and new ones selected to best illustrate the different antenna types. --ChetvornoTALK 13:52, 22 June 2015 (UTC)
I helped make the "eyesore", but I made it out of a bigger eyesore ;). Headings like "Basic antenna models" were someone else's idea, I just moved images to that context. Looking at it a year and a half later I would delete the galleries, they seem to have no encyclopedic value per WP:IG. In other words I agree with the idea of a rewrite. Fountains of Bryn Mawr (talk) 19:44, 22 June 2015 (UTC)
I see what you mean, it's better than it was. Sorry, "eyesore" was a little strong. Actually I think the images could serve a purpose. One of the things I would want from this article, if I were a general reader, is to see what the different types look like. Antennas are very visual things; they are out where people can see them, and have distinctive shapes. I'm always noticing new antenna types I've never seen before and wondering what they are. If the "Antenna types" section had one good image of each of the major antenna types along with its description, it could serve as a "beastiary" where readers could recognize antennas they have seen? --ChetvornoTALK 21:02, 22 June 2015 (UTC)