Talk:Antenna (radio)/Archive 1

This page is an archive of past discussions. Do not edit the contents of this page. If you wish to start a new discussion or revive an old one, please do so on the current talk page.

Staggering Length of this Article

This article has grown by each of us throwing in a nugget until it is overwhelming textbook. Check out this TOC! I have seen some of this addressed better in other articles anyway. Someone please help list the mainstream stereotype antenna ideas that need to be put in front of someone who looks up the word "Antenna." Can we move or merge the esoteric issues that antenna experts want to know about into specialized articles? If we do this will everyone be hurt if we don't each get our favorite topic covered well enough? I propose the following outline; can anyone help make it 'good'?

-.-

Lead Sect (Layman’s view of ‘antenna’)

Historical Origins (Hertz dipoles, loop, monopoles...)

Properties of Antennas (Briefly! "survey" level)

Resonance (length and loading)

Gain

Bandwidth
Impedance
Radiation pattern and reflectors
Polarization
Efficiency
Transmit & Receive Reciprocity

Kinds of Antennas

Imaginary Ideal Isotropic Radiator
Monopole (Distinction between ground and counterpoise, -Vertical, -Long Wire, -Beverege, -Helical)
Dipole (-Basic Dipole; -Quad; -Yagi; -HF Curtain)
Inductive Loop
Waveguide horn and orfice

John 07:05, 23 November 2006 (UTC)

I already started a subpage dedicated to television antennas. They are unique and common and look cool. Daniel Christensen (talk) 19:06, 10 November 2009 (UTC)

Please note that per WP:LINK, this article should contain only one link to any other Wikipedia article. --Jc3s5h (talk) 20:06, 10 November 2009 (UTC)

AltairPayne (talk) 15:43, 11 August 2010 (UTC)

Antennas: A decent taxonomy of antennas is necessary but not sufficient. I'd like to take a stab at a comprehensive taxonomy.

A taxonomy useful for teaching engineers, soldiers and hobbyists begins with basic elements: the simple electrically small dipole and loop, resonant loops and dipoles, their analogs, slots and patches, non-resonant elements. Then proceed to methodically map out the antennas that can be constructed from arrays of simple elements. For instance the Yagi-Uda dipole array versus the log-periodic dipole array, which look similar but are functionally quite different. Again, their analogs are with us such as waveguide fed planar slot arrays used on aircraft weather radars, etc. Generally, arrays may be linear, planar, periodic, log periodic, fractal, etc. Yet more generally an antenna is a discrete optical device, a resonant dipole transmits and recieves photons of RF energy. This leads to treatment of antennas with reflectors, lenses, etc.

All along, the taxonomy can sprout links to articles on particular antennas, such as resonant wire antennas or Yagis, since the taxonomy itself could easily become unwieldy.

Should the taxononmy be an article unto itself? A brief taxonomy in the main article, and a detailed and exhaustive one separately?

The taxonomy of antennas is not sufficient, below based on the previous suggestion.

Lead Sect (Layman’s view of ‘antenna’)

Historical Origins (Hertz dipoles, loop, monopoles...)

Properties of Antennas (Briefly! "survey" level)

   * Directional vs omni
   * Radiation pattern 
   * Gain  (vs  directivity)
   * Efficiency
   * Transmit & Receive Reciprocity
   * Bandwidth
   * Resonance
   * Impedance
   * Polarization

Brief Taxonomy of Antennas

* Simple elements
   * Imaginary Ideal Isotropic Radiator
   * Simple elements: infinitesimal dipole and loop
   * Practical elements: large / resonant dipole and loop
   * Monopoles, slots, patches etc. derived from above 
   * Distinction between ground and counterpoise
* Arrays of simple elements
   * Endfire arrays of dipoles, Yagi vs LDPA (below),
   * Other Endfire arrays: quads, loops etc.
   * Broadside arrays: curtains, planar dipole or slot arrays (radar)
   * Log periodic arrays for wide bandwidth: LPDA, spirals, conicals, sinuous
   * Aperiodic arrays and fractals
   * Non-scalar antennas: bicone, discone, etc
   * Travelling wave antennas: helical, beverage, rhombic, "infinite Yagi" as an ideal
* RF optics
   * Waveguides, horns
   * Reflectors and lenses

Uses of Antennas << where anybody can find a place to link to their favorite "nuggets"

   * Broacdasting, fixed and mobile <<links out to ants for SW, AM, FM, TV
   * Two-way LOS radio, cellular <<link out to cellular ants
   * Wireless data (WiFi, Bluetooth)  <<links to commercial and DIY (pringles can) ants
   * Satellite and satellite reception (fixed)  <<link out to TV dish ants
   * Aeronautical and marine communications (LOS and mobile satellite)
   * Radar <<link out to weather, primary and secondary air traffic surveillance radars
   * Microwave fixed and satellite
   * HF and shortwave   <<link out to Shortwave, CB & Ham ants
   * VLF and ELF

Well, it ain't perfect, but the basic idea is for "properties" to be a brief tutorial overview, the taxonomy to become a place to hang all the technical articles dealing with specific types of antennas with theory and synthesis, and the "practical uses" gives a home for anybody's link to their favorite application

External link question

I think that this is a very useful link for readers. I think it is especially true given the overly technical nature of this article. I would like to see this added to the external links section. Thoughts?

"Antenna Guide" A practical guide to selecting a WiFi antenna.

Networkingguy (talk) 17:05, 26 February 2008 (UTC)

Nature of the EMF

What is the amplitude of the EMF that is applied to a transmitting antenna to provide a signal?

The amplitude depends on the desired power output. Family Radio Service is limited to 500 miliwatts. 5 watts is considered to be the maximum safe power output for a handheld radio. 50 watts is considered to be the maximum safe power output for a radio with the antenna on a car roof. Commercial radio stations use power on the order of 20 kilowatts. See also Effective radiated power. --ssd 05:37, 9 January 2006 (UTC)

And the RMS voltage (amplitude) applied to the antenna can be calculated from the power given above:

V_{rms}={\sqrt {PR}}\,

where R is the characteristic impedance of the antenna (often 73 ohms). The RF voltage on commercial broadcasting antennas can reach tens of thousands of volts. --Chetvorno^TALK 23:56, 9 January 2010 (UTC)

Electrically Short Antenna

The electrically short antenna is far less than 1/4 wavelength in length. Unlike nearly all other antennas in this list, this antenna detects the electric field of the wave instead of the electromagnetic field.

I don't understand this statement. I'm fairly certain the distinction made between "electric field" and "electromagnetic field" doesn't make any sense, but could somebody please confirm?--Jfbolus 07:11, 29 Mar 2005 (UTC)

There is a difference since you can receive more or less completley only the electric component of the electromagnetic field. There are also antennas for the magnetic component for ex.: coil antennas, loop antennas, ferrite antennas. --Xnor 17:55, 18 May 2005 (UTC)

If you're trying to say that a short antenna is excited only by the electric field of a propogating wave, then you're correct, but the quoted statement still doesn't make sense. The electric field is part of the electromagnetic field. The whole "electrically short antennas" bullet point should probably be removed anyway, since its already covered in the Dipole antenna page. --Jfbolus 12:57, 18 November 2005 (UTC)

Stuff to add to this article

I'd add this stuff but I either don't understand it yet or am too (tired | busy | distracted) to do it just now. If you know something, feel free to add it yourself.

More antenna models:
- Log-periodic antenna
- feed horn
- corner reflector (almost always used on tv yagi's)
- patch
- bow tie / Biconical antenna / discone variations
antenna like things that aren't antennas
- dish (and variations)-- reflector that still needs an antenna at the focus

Added this (paragraph about Parabolic antennas)and a link to the parabolic antennas page OH3GPJ --Miikka Raninen 23:59, 14 April 2006 (UTC)

- lens -- practical at >10ghz(?) negative refractive index! wave guide construction, diameter <4 ft?
incorporate as many of Glossary of antenna terms as reasonable

(Is it possible to have too many antennas listed here? Is order important? They're already listed more or less in order of complexity I think.) --ssd 07:25, 17 Apr 2004 (UTC)

Actually, I now think this article is long enough. Additional antennas that have their own page should just be added to Category:Radio frequency antenna types. They should only be added to this article if they are really common antennas or are too short to have their own article. --ssd 13:50, 31 Jul 2004 (UTC)

Plural of Antenna

What should the plural of antenna (in the sense of a radio antenna) be? Several sources give it as 'antennas' and the insect variety of antenna as 'antennae'. I have always used the latter for radio antennae. Are both correct, or, as I suspect, the 'American' spelling the one that prevails?

People who know latin or greek use antennae. People who know english use antennas. I suppose both are correct in context. --ssd 13:50, 31 Jul 2004 (UTC)

Isn't antennae used when referring to more than one insect antenna, while antennas is used for radio antennas/aerials? --/ɛvɪs/ /tɑːk/ /kɑntɹɪbjuʃ(ə)nz/ 18:02, July 20, 2005 (UTC)

The plural of antenna is aerials--Dumbo1 22:49, 11 August 2005 (UTC)

That's like saying the plural of pig is porks. --ssd 05:34, 8 January 2006 (UTC)

The correct plural of antenna is, in the radio sense, antennas. The correct plural of antenna, in the biological sense of what insects have on their head, antennae. They are not interchangable, and antennae is wrong for radio usages (though still occasionally used within the industry by people who think they know better). DWaterson 11:33, 28 February 2006 (UTC)

In the UK at least, engineers use the plural Antennas but as this is a little known fact outside the field you will hear the general public speaking of Antennae. I asked the BBC about this a few years ago and they agreed to change policy on their news web site news.bbc.co.uk and you will see (radio) Antennas used consistently these days. CDovener 17:22, 24 March 2007 (UTC)

That sounds consistent with what I have heard. Also, Latin bases are very important in biology, but precise engineering and physics are in mathematics, so there is less need for classical languages. David R. Ingham 07:18, 2 March 2006 (UTC)

transmitting vs. receiving antennas

Someone added a comment that an antenna can't be designed for both transmitting and receiving. This is a false statement. It's something I do every time I make an antenna.

Transmitting antennas are really a subset of receiving antennas. If you design it to transmit well on a specific frequency range, it will also receive well on that range, and with the same radiation pattern. Designing and testing for optimal transmission also insures optimal reception.

The biggest difference between the two is that transmission antennas work best if impedance matched. With a receiving antenna, the receiver(radio) needs to be optimally impedance matched. (It helps if the radio and antenna are matched to each other, but the load is more critical--as already stated in the article.)

Also, most antennas desgined for receiving only are tuned for broadcast frequencies, where the transmitter uses extremely high power (KW typically), and so can be smaller and still get enough input power to be effective.

This type of info would be more appropriate for a real antenna theory article that would go into depth in theory, rather than just glossing over it as I have in this article.

It's not quite true that transmit antennas are a subset of receive antennas (I give an example in the article, now) - a receive antenna may be designed to lose efficiency in favor of noise rejection. Such designs are common in amateur low-band setups. In fact, I've used one: we had a big delta loop and a 120ft tower, and the best configuration was to transmit into the tower and receive using the loop.

That said, I think an antenna theory article would be excellent - of course, it can't cover the whole subject, but a good introduction would be wonderful. I don't know nearly enough about it. --Andrew 03:44, May 10, 2004 (UTC)

Good point, and I've also desgined antennas specifically for receiving. I may tweak the emphasis a bit. Good job on adding polarization--I forgot about that. I may expand on it a bit, at least link it in right. --ssd 04:10, 10 May 2004 (UTC)

Oh, btw, all components in an antenna (including wire!) are important for maximum power. I generalized your otherwise excellent wording. Note that even coax feedline is susceptible to diaelectric breakdown, but that kinda detail is probably too much here.

I heard a rumor that some transmitting antennas use cryogenic superconductors for something, presumably to allow increased power with lower resistance. I've not actually seen any literature on this, or I'd add something about it. --ssd 04:43, 10 May 2004 (UTC)

I read it is used for sharp filters and sensitive recievers in cell phone basis stations--Arnero 21:37, 30 December 2005 (UTC)

After studying for Extra, I now understand why. Cooling various parts of the system can lower the noise floor (and noise figure) in certain components (as you said). --ssd 05:28, 5 September 2007 (UTC)

Antenna Theory Section

We need to work on an antenna theory article, or severly work on this article. As you say, a lot is glossed over and said to be difficult to do. More explanation is needed for everything! I am very interested in working on this topic with you. Please reach me via email at brandon.irwin <at]gmail dotcom Brandon.irwin 21:46, 9 Jul 2004 (UTC)

Antenna theory is now scattered between various specific articles and Antenna measurement. --ssd 05:37, 26 August 2007 (UTC)

Canadian Flag

I like Canada as much as the next man, but a flag on the antenna? C'mon guys. We all know how the reaction would be if it were a US flag up there. --195.195.244.6 15:34, 9 Mar 2005 (UTC)

Feel free to supply a better antenna picture (this one is duplicated on the Yagi page anyway) but the flag was actually up there, and it is a common tradition to fly flags on antenna towers... --Andrew 17:18, Mar 9, 2005 (UTC)

I'm rather offended that a yagi antenna image was used instead of a dipole! In fact, I'm so outraged that I refuse to change the picture. --Hobophobic 21:26, 14 Mar 2005 (UTC)

LOL. You are jusy a yagiophobe! Stop trying to keep the yagi down. Rob 12:00, 10 March 2006 (UTC)

HF dipoles are very difficult to take pictures of. Sometimes all you get is a picture of a tower with invisible guy wires (which are really the antenna, not the tower). It might be fun to get pictures of more interesting antennas, but meanwhile, the yagi with the canadian flag does fine IMHO. It's more typical than some of the more scary antennas in some of the antenna articles here, and less boring than a dipole. I too refuse (for now anyway) to replace the picture. :) --ssd 12:38, 15 Mar 2005 (UTC)

Now, now, there are other interesting-looking antennas. Some UHF or microwave stuff is really interesting-looking. I'd be happier if we had a separate picture for here and for Yagi antenna. Somewhere I have a picture my parents took of a 42-element 2-meter quagi they built; I can ask them for permission to use it next time they see it. In any case, until we come up with a picture to replace it with, talk about replacing this picture is rather silly (even more so than otherwise, I mean).

Hey, I wonder if there's a picture (or article) for Armstrong rotator? I think you can see it hanging from one end of this yagi... --Andrew 17:53, Mar 15, 2005 (UTC)

Impedance? Electrically short?

Is there any references to the discussion in the article about impedances for recieving antennas? This RF-engineer does not understand the text... And is there any reference to the electric field vs. electromagnetic field part in the description of short antennas? I dont follow that explanation at all...

Hey! Feel free to improve it more! I believe the text I added is accurate, but others have added things I can't verify, and I'm only an amateur, so I could be wrong too. All my text is refenced from one of the ARRL books, probably either the Antenna book or the Handbook. --ssd 06:28, 29 Mar 2005 (UTC)

Gain and how does it work

I don't clearly understand yet how Gain works. Imagine I have 1 Watt for my isotropic antenna. No i use a gain antenna. Logically, this new antenna won't have more than the 1 Watt provided by the circuit. So, how does the gain antenna get more power to send? Is the antenna amplified? That would need the antenna to be powered by another energy source additionally. Actually, are there antennas that can amplify a signal by using an additional energy source connected to the antenna? Thanks, --Abdull 09:48, 5 Apr 2005 (UTC)

Well, there are setups where you put an amplifier on the output of your radio; sometimes it lives on the antenna. The opposite situation is actually more common: many antennas (especially for radio telescopes) have a receive amplifier as close to the antenna as possible to reduce the thermal noise.

But this is not what is meant by the gain of an antenna. In your example, the antenna still radiates only one watt. But there is normally only one (or a few) direction you care about - toward the receiver. So if the antenna is pointed towards the receiver and puts out all its power in a hemisphere (instead of a sphere) it will have a gain of 2 (3 dB). In practice, antenna radiation patterns are complicated, but a Yagi antenna (for example) puts out most of its power in one direction, so that the signal strength in that direction is increased compared to an isotropic antenna (at the cost of other directions).

This is complicated by the existence of "omnidirectional" antennas with gain. In fact such antennas are not omnidirectional; normally there are directions that are almost certain not to be useful to send signals to: stright up and down. For HF antennas, radiating at a low angle results in long skips and better communications over long distance, so (for example) a 5/8th wave vertical has gain because it suppresses radiation stright up. --Andrew 10:19, Apr 5, 2005 (UTC)

There is still only 1 watt radiated but it's concentrated like a searchlight in one direction, which makes it as powerful as say 5 watts spread in all directions. --Joe VK4TU

patents

I find it surprising that there's less than thirty patents on antennas. I'd think there'd be thousands. Are these patents being added just the significant ones, or just the recent ones, or just random ones? If this is only a few recent ones (as I suspect is the case), is it really appropriate to add these at all? --ssd 8 July 2005 04:39 (UTC)

I can't see that they belong here without any accompanying or descriptive information. I will remove them until they can be described or put into some contextual purpose for the article. Wiki is not a raw datadump... --Blainster 17:04, 14 July 2005 (UTC)

Gain, what is it?

Under the definition of gain seen here http://en.wikipedia.org/wiki/Gain

"In electronics, gain is usually taken to mean the ratio of the signal output of a system to the signal input of the system. A gain of 10 would imply that a property of the signal (usually voltage or power) had increased by a factor of 10."

Which sounds an awful lot like amplification http://en.wikipedia.org/wiki/Amplifier

"An amplifier can be considered to be any device that uses a small amount of energy to control a larger amount, although the term today usually refers to an electronic amplifier. The relationship of the input to the output of an amplifier--usually expressed as a function of the input frequency--is called the transfer function of the amplifier, and the magnitude of the transfer function is termed the gain."

And http://en.wikipedia.org/wiki/Electronic_amplifier

"An idealized amplifier can be said to be "a piece of wire with gain", as the output is an exact replica of the input, but larger."

Which sound like what the term "gain" should be.

Now this page is saying something completely different.

"An antenna has gain if it radiates more strongly in one direction than in another. Gain is measured by comparing an antenna to a model antenna, typically the isotropic antenna which radiates equally in all directions."

Here we are defining gain as the difference in signal strength in one area vrs another area for an output signal only. It considers nothing to do with an amplification procedure.

Correct. So there are two meanings of "gain" as used in electronics. --Heron 18:27, 11 August 2005 (UTC)

Since an antenna has only one pair of terminals, a supplementary reference is needed for the generalization. This is usually taken as the gain of a perfectly efficient isotropic radiator. --David R. Ingham 19:34, 11 August 2005 (UTC)

An important point to note with amplifiers is that we are not creating energy out of nothing.. that is not possible. We will be having a DC supply which supplies the energy for amplification. A crude definition of antenna is it's a passive device which radiates energy.So the gain here is not the relation between the output and input but it tells us about the directivity of an antenna. that is maximum power transferred.

Contradiction, what's correct??

One of the two (bolded) statements below must be false. Which one? If you know, please correct it :)

The small loop antenna, also called the magnetic loop antenna is less than a wavelength in circumference. (Typically less than 1/10 for a receiving loop, less than 1/4 for a transmitting loop.) Unlike nearly all other antennas in this list, this antenna detects the magnetic field of the wave instead of the electric field. As such, it is less sensitive to near field electric noise when properly shielded. The receiving aperture can be greatly increased by bringing the loop into resonance with a tuning capacitor. Due to the small size of the loop, the radiation pattern is 90 degrees from that of the large loop. The radiation pattern is perpendicular to the plane of the loop, with sharp nulls in the plane of the loop.

The electrically short antenna is far less than 1/4 wavelength in length. Unlike nearly all other antennas in this list, this antenna detects the electric field of the wave instead of the electromagnetic field. Its receiving aperture can be greatly increased by increasing the voltage; by adding an inductor or resonator tuned to resonance with the signals of interest. Electrically short antennas are typically used where operating wavelength is large and space is limited, e.g. for mobile transceivers operating at long wavelengths.

TH 12:43, 13 October 2005 (UTC)

There is no contradiction. The loop antenna is just that - a closed loop of wire. The short antenna is NOT a closed loop - it is a wire with one end connected to the radio and the other in free space. They are two different things. N0YKG 13:46, 13 October 2005 (UTC)

Surely there is a contradiction, if there isn't it's not explained well enough for normal people (like me) to understand. Both paragraphs claim that "unlike nearly all other antennas in this list", they detect respectively the electric field rather than the magnetic field of the radio wave. So "Unlike nearly all other" must be wrong since that could only possibly be true for one of them.

TH 13:56, 14 October 2005 (UTC)

The difference may not be clear, but that does NOT make this a contradiction. However, see the rewrite, and see if that helps. N0YKG 16:00, 14 October 2005 (UTC)

The rewrite helped me understand the facts, and the new explanation about the electrically short antenna is much clearer. But I still see a blaring contradiction: The section about the small loop antenna claims that "unlike nearly all other antennas in this list, this antenna detects the magnetic component of the electromagnetic wave instead of the electrical component" while the section about the electrically short antenna claims that "unlike nearly all other antennas in this list, this antenna detects the electric field of the wave instead of the electromagnetic field". It follows from simple logic that either the majority of the antennas detect the magnetic fields, and the first statement is right and the second wrong, or the majority detect the electric field and the first statement is right and the second wrong. I think that the electrically short antenna is the exception here and that makes its description correct, while the description of the small loop antenna should be corrected. But I leave it to you or someone else with expertise in the field to actually do the change. TH 15:18, 22 October 2005 (UTC)

OK, what I will do is change the loop to read "detect the magnetic component of the signal only" and the short antenna to be "The electrical component only" - the other types detect both aspects of the field. Better? N0YKG 00:55, 23 October 2005 (UTC)

Excellent, thanks a lot. I missed the idea that the others detected both types, I thought the majority only detected the magnetic. It is much clearer now. TH 22:32, 23 October 2005 (UTC)

Antenna / Ariel

What is this US / British English thing ? Never heard of the difference in terms of variants of English. From my British education the difference is that an ariel is only designed for reception, whilst an antenna is designed also (or solely) for transmission.

Do others agree ? --jrleighton 15:01, 17 October 2005 (UTC)

According to the article, most antenna designs work equally well for reception and transmission of the wavelenghts they support, so that distinction doesn't seem to me to make much sense. TH 15:20, 22 October 2005 (UTC)

Antenna / Ariel

Do you mean Antenna / Ariel or should it rather be Antenna / Aerial? AA2HT

The term 'antenna' (pl. 'antennas') is used throughout the microwave and RF industry in the UK. 'Aerial[s]' is now only used colloquially (i.e. outside the industry). I've got two UK written and published books infront of me now 'ANTENNAS': F. R. Connor 1972-79, and 'Short Wave Wireless Communication including Ultra-Short Waves': A. W. Ladner 1932-50, which contains 'Chap. VIII Aerials' and 'Chap. IX Aerial Arrays' - so usage probably changed between 1950 and 1972. --catslash 14:37, 28 July 2006 (UTC)

I've always believed an antenna is resonant at the operating frequency e.g. yagi, dipole etc. whereas an aerial is a "rough and ready" non-resonant device e.g. an untuned length of wire used over a large frequency range without any particular concern for efficiency.118.208.125.94 (talk) 06:46, 19 July 2008 (UTC)

Well, that'd be wrong too. Most receiving antennas are either not resonant, or are barely resonant. But I just found a whole book of non-resonant transmitting antennas. Please give up on trying to find a distinction between ariel and antenna. There really isn't any. --ssd (talk) 04:56, 14 September 2008 (UTC)

Yes, rhombics, V's and T2FD's are non-resonant antennas which can be used for tranmission as well. Their efficiency may suffer on some frequencies, but they do work. Sv1xv (talk) 09:29, 14 September 2008 (UTC)

My original distinction centered around resonance/non-resonance. How does usage (transmitting/receiving) make this "wrong"? —Preceding unsigned comment added by 118.208.120.70 (talk) 10:06, 27 September 2008 (UTC)

Because antennas can be either resonant or non-resonant, and they are still antennas. The only distinction beteween ariel and antenna is that the first is a colloquial term whose use is fading. There is no difference in meaning at all. --ssd (talk) 13:02, 27 September 2008 (UTC)

Loop antenna

Loop antenna is currently a redirect to this article; it should be replaced with an expanded article. --ssd 23:42, 28 December 2005 (UTC)

Just to say. The chapter on the large loop is wrong. Read the Balanis, it is the best book ever on antenna,actual and both practical and academic (It is not spam, it is true). A small loop has its maximum gain on the plane of the loop, but when you increase the size of the loop, this maximum shift until the circumference have reached the same size as the wavelength where the maximum gain is perpendicular to the plane of the loop (on the axe).--85.218.2.215 19:52, 2 August 2006 (UTC)

All of the above is wrong. You've got it exactly backwards. --ssd 07:32, 26 August 2007 (UTC)

OK Balanis is pretty good, but if you don't want to go out and buy it, a good text/reference book available online in about 20 separate PDF chapters is Orfanidis. I've added a link to it in 'External articles and further reading'.--catslash 10:23, 3 August 2006 (UTC)

Loop antenna now has its own article. Previous text here was moved (and deleted) and then corrected, and referenced. --ssd 08:07, 26 August 2007 (UTC)

Overview section

IMHO the overview section is a bit rambling and unclear. I'm not sure it really adds any information. What do you think? (I wish someone would either delete it or rewrite it. Or maybe just trim it down a bit?) --ssd 05:46, 8 January 2006 (UTC)

Can the article be structured like this:? --Arnero 12:15, 8 January 2006 (UTC)

(NO -- deleted your bad outline to prevent confusion --ssd 07:34, 26 August 2007 (UTC))

I can't say I care for that. Time vs. Space is not really a valid separtaion of concepts, and I'm not sure that separation is needed. Also, mixing antenna models with theoretical discussion is not a good idea at all. Also, you have miscategorized the directional vs. omnidirectional antennas, which is just further proof that this heirarchial structure is inappropriate. (ex: loop can be omnidirectional, but is usually directional. The reverse is true for dipole.) Perhaps I'm missing the point of this reorganization?

Also, looking at the current list of antennas, I would object to any structural change that did not keep the isotropic and dipole antennas first. The yagi should probably be next, but I could be convinced that one of the others is more common. --ssd 06:16, 9 January 2006 (UTC)

Time is what every electrician understands (as it is 1 dimensional) and were many wiki links are possible. Space is very poorly understood by most readers and hard to show as I have not seen any 2d radiation pattern in wiki, yet. (small loops are omnidirectional, big ones are not. Same with electric dipole antenna, if you omit the coil and instead tune it to high frequency by a capacitor, it will not radiate a dipole pattern).--Arnero 01:38, 13 January 2006 (UTC)

dipole antenna has a nice 2d radiation pattern diagram. Small loops are very directional. They are one of the classic direction finding antenans. Large loops can be omnidirectional if they are oriented horizontally. Any antenna, when used out of its rated frequency, will act differently, and is pretty much not the same antenna. --ssd 07:06, 13 January 2006 (UTC)

Ideal dipole (to show in introduction). electric, magnetic.
Praktikal dipole (to show in a separate article) electric. magnetic
2d radiation pattern diagram. What is more demonstrative: Radiation pattern or [1].
What is simpler: radiation pattern or [2]
"omnidirectional if they are oriented horizontally". Maybe we should stop thinking in terms of ground based antennas. The overview article should also hold for cell phones, satellites, and airplanes and there "omnidirectional" does not mean "along the horizon"
"out of its rated frequency"> But the coil is ok, I hope: [3]

--Arnero 14:26, 13 January 2006 (UTC)

You can't stop thinking of antennas in terms of the ground unless you are an astronaut or a satellite. It is important if the loop is horizontal or vertical not because of ground itself, but because of the orientation of the radiation pattern with respect to a potential population of receivers. --ssd 17:00, 8 April 2007 (UTC)

Ordering of Ideas

In the Antenna parameters section you have an overview of antenna parameters subsection. This makes sense, but it's put in the middle of the other subsections, this does not flow right. Either put it first or put it last, but not in the middle.

One of the problems with this article is it's very hard to read. The concepts are very jumbled as it's layed out in general. Someone needs to go at this article with an axe and chop out 1/3 to 2/3 of the content... some of which could be farmed out to other articles on those particular concepts. Remember this is an encyclopedia, not a scientific text. The article needs to be clear and to the point, crossreferenced with supporting material. The article should not contain enough information to make anyone an expert on this subject, rather give a fair working concept of it. As it stands now, I have a hard time understanding the article while already knowing the subject.

The A few basic antenna models is anything but. I don't have an exact definition of the word few, but this ain't it. As it stands now it's just a list, it doesn't really support any content and is confusing in its layout. I would think a few antenna models would be more like: Those that detect the electro-magnetic field, those that detect the electric field and those that detect the magnetic field. -That's a few. I wouldn't call the section a few types of anything at all, it isn't very encyclopedic. But whatever it's called, it ought to be shorter! Shove the details to articles in Category:Radio frequency antenna types. Anonym1ty 22:46, 11 January 2006 (UTC)

I can't fairly address the antenna parameter section, but I still don't think time vs. space is relevant here; frequency is not really time. Bandwidth is not time at all. Impedance has nothing to do with time. Polarization is not space (it's shape or direction). None of the antennas should be categorized as "time" or "space" as they are both or neither. Organization is needed, but I don't think time/space is the right concept to organize on.

The basic antenna model section has run away with itself (I think we totally agree here), and most of the content there should be moved to individual articles. I think specific radiation pattern and methods of combining elements are much more important than E or M field. Perhaps, rather than this huge list, it should just list isotropic, dipole FAMILY, loop FAMILY, yagi, phased array (very different), and maybe synthetic aperture. Each of these should be very short; Yagi I think is perfect. Isotropic is long, but good for its significance. Dipole should be two sentences. The rest should probably be one sentence. All the removed material for the rest should go to individual articles. As they are removed, a mention is needed in the parent article for the family (some of the dipoles are already there), and make sure (as you say) it is in category:radio frequency antenna types. The antennas that are redlinked need articles. Perhaps what is here would be a good stub start? --ssd 07:26, 13 January 2006 (UTC)

Introduction

Some antennas have dielectric or magnetic material. This may not be needed in the first paragraph, but to me it sounds funny to say they are composed of conductors. Less basically, there are structural materials and ray domes.

Now that Si can be used for LEDs and soon lasers, chips may have optical frequency dielectric antennas soon. (With lenses [or mirrors] to focus to and from the plane of another chip.)

When I was a kid, AM radio antennas had iron cores. Maybe some still do. For RAM coatings, and I think also for antennas, magnetic materials give better band widths to thin coatings or small antennas than can (theoretically) be obtained with only conductors and dielectrics. David R. Ingham 02:42, 13 January 2006 (UTC)

Conventional antennas generally avoid dielectrics (as opposed to outright insulators) as they tend to introduce loss, but you are right anyway. The AM broadcast bands use a large wavelength, and so the loopstick is the most popular AM antenna. The "stick" in loopstick is a ferrite powder core (note quite the same as iron). Many commercial quality colinear antennas (very long stick) have a copper core for lightning conduction purposes. -ssd 19:05, 16 January 2006 (UTC)

slow revisions, other ways to reduce size

The practical antenna section is (I think we all agree) too long. I'm going to slowly review each one that has its own article, make sure everything listed here is in the main article, and then cut what is here to the bare essentials. My goal is to make all but the first two practical antennas (with their own articles) about two sentences long, but I may not get it that tight. --ssd 06:58, 13 February 2006 (UTC)

well unfortunately added to your work by adding a paragraph about parabolic antennas OH3GPJ --Miikka Raninen 23:59, 14 April 2006 (UTC)

The loop and electriclly short antennas need their own pages so those sections can be shortened. --ssd 14:39, 14 March 2006 (UTC)

Everyone want their antenna to be electrically small, but still broad band and high efficiency, so it does seem there should be a page on that subject. There are theoretical limits that could be explained. "Super-gain" antennas could be a sub-heading. David R. Ingham 06:02, 15 March 2006 (UTC)

I like the idea, but what would you put on a page that just lists antennas that is not already in Category:Radio frequency antenna types? --ssd 17:10, 10 May 2006 (UTC)

Origin of word "antenna"

Added origin of word antenna to the introduction, as this is something I never knew until recently, despite working with antennas for over 35 years. Yaf 16:31, 31 March 2006 (UTC)

Polarization secton

The section on polarization has become wordy and redundant. I think I spotted the same phrase in there several times. Also, I think the loss due to mismatched polarization is overstated. I seem to remember (i.e., without references) that horizontal vs. vertical polarization is only a 7dB loss. Circular polarizations of opposite circularities is about 14dB loss. Neither of these could be described as "tens of dB"... --ssd 13:34, 10 May 2006 (UTC)

Marconi and term "Antenna"

Did something change? pole in Italian is "palo" OR is translate.google wrong? 204.56.7.1 16:20, 27 June 2006 (UTC)

What is and isn't an antenna

The paragraph beginning with The use of "antenna" usually excludes non-communication applications needs to be sourced (to the patent class description?) and clarified a bit.

My knowledge of physics is limited, but I'm fairly sure that electron beams (beta rays and cathode rays) are not usually described as electromagnetic radiation.
Should radiant EM energy be described as having a kinetic component?
What are "partial rays"?

-- JP 70.150.177.5 16:10, 17 July 2006 (UTC)

Antennas are certainly called 'antennas' when used in radar, navigation, meteorology and EMC testing - and possibly in some other areas, such as radio astronomy. The whole Terminology section might benefit from radical pruning? --catslash 15:43, 28 July 2006 (UTC)

Headings name the article title

Wikipedia:Manual of Style (headings) includes mention that headings should not repeat the article title, if possible. It can be assumed that we are talking about antennas. --Charles Gaudette 23:52, 16 August 2006 (UTC)

angle of incidence

I'm pretty much confused by this "angle of incidence". As illustrated in the picture, the angle (phi) is the angle between the horisontal axis and the direction of the reflected wave. However, in it's own article, the angle of incidence is defined different, so it actually comes as 90-(phi). Which is correct? Did I miss anything ?

No, you are right. The angle

\scriptstyle {\theta }

(theta) in the drawing is not the angle of incidence. I will correct my mistake. LPFR 06:26, 5 September 2006 (UTC)

Some clean-up

I erased two paragraphs in "Terminology". The first one, beginning "The use of antenna... ", used to many incorrect terms and mixes. I did not found how to rearrange it. The definition of antenna at the beginning of the page is complete. The second paragraph, redefined the term "radio waves". This definition is not as good as the one given in radio waves, linked in the first line of the page. LPFR 08:56, 8 September 2006 (UTC)

Good work! - this clean-up was long overdue (see above). --catslash 14:53, 8 September 2006 (UTC)

Physical background

As some wikipedians seem to ask for a more theoretical basis, I changed two descriptive paragraphs about "how the antenna work" for a more "academic" version. LPFR 14:09, 8 September 2006 (UTC)

A Query..

Does anybody hv the idea about why an antenna length should be a multiple of the wavelength?? This is a question for which i hv not found an answer in any book ( as far as i hv seen).. Can anybody suggest an answer or a book..

The reasons is that the impedance of the antenna is resistive (with no reactive part) when the total length is near (but not exactly) a multiple of half wavelength. Adaptation to the feeder cable is easier as there is no capacitive or inductive part to compensate. This is a good condition but it is not necessary for an antenna to emit or receive. LPFR 12:28, 9 September 2006 (UTC)

Thank you very much. But i hv another query. Can we have a similar resitive antenna at some other lengths larger than half the wavelengths, say 1000 times the wavelength of the signal.

An alternating voltage applied at one end of a wire creates a traveling wave in the wire. This traveling wave is formed by an alternating current in the wire plus a tension on the wire. In an infinite wire, the wave travels down the wire and radiates power in the form of an emitted radio wave. Therefore, the current and the voltage attenuate as the wave progresses.
When the wave arrives to the end of the wire, a new wave is created. This wave travels backward and, added with the forward traveling wave gives a zero current at the extremity of the wire. The reflected wave also radiates power and attenuates. When the reflected wave arrives at the feeder cable, some of it enters the cable and the rest reflects and goes back in the forward direction. And so on. The phase of the sum of all the reflected waves, at the feeder cable, gives the impedance of the antenna. If the phase is 0° o 180° the impedance of the antenna will be resistive (no reactive part). If not, it will be more or less capacitive or inductive.
This is the reason why the impedance of an antenna depends on its length. However, when the wire length is too long, the amplitude of the reflected wave becomes negligible, and the impedance of the wire does not change with the length. In the Smith chart, as the length of the dipole increases, the impedance of the antenna describes a spiral line closing to the point corresponding to twice the impedance of an infinite wire. This impedance depends on the diameter of the wire, but it is of the order of the impedance of free space (the wikipedia page on this subject is bad), about 377 ohms. Your almost infinite dipole, which is no more a dipole or a resonant antenna, will have an impedance of about 800 ohms (resistive), and a gain of 15-20 dBi (but this is just my guess). LPFR 08:02, 14 September 2006 (UTC)

Excellent explanation, but you talk only about the wave in the wire. When the wave is radiated from the wire, you get wave fronts in free space. These wave fronts interact with each other constructively and destructively. If the antenna is longer than half a wavelength, wavefronts from neighboring sections will cancel out and reduce antenna gain. To fix this, a phasing section (as in the Super J-pole antenna) can be added, or the phase can be reversed outright (as in the colinear antenna). Antennas of this design have a 2-d omnidirectional pattern that is a very flat disk in 3-d (the more sections, the flatter the disk). --ssd 20:20, 14 July 2007 (UTC)

Reordering the article

I wish to know what you think about reordering this article in this way:

Definition: unchanged.

Terminology: Shortened to origin of the word and included in the definition on antenna.

Antenna parameters (definitions stuffed and completed if necessary)
- Working frequency / bandwidth.
- Directive gain (definition, etc.)
- Impedance.
- Radiation patterns (different possible drawings). Half power lobe width.
- Polarization
- Efficiency
- Cost. Say that cost is also an important parameter and that there are cheap antennas and very expensive ones (phased arrays).
Receiving antennas. Reciprocity: same parameters as in transmission. Equivalent circuit. Effective length. Capture area. Maximum available power.
Physical background. Unchanged.
Practical antennas. To be rewritten, including problems of adaptation and SWR that are now in "overview of antenna parameters".
Effect of ground. Unchanged.

I suggest putting a link to a new page "antenna models" containing a list with a brief description of several antenna types with links to pages dedicated to each antenna (if there is enough stuff). The idea is to keep in the Antenna page only the properties and aspects common to all antennas and send each type or family to a specialized page.

I do not think feasible to give a classification or an order for antennas. There are too many possible criteria: resonant/non-resonant, electric/magnetic, simple/composite, professional/amateur, linear/circular polarized, etc. I suggest using just alphabetical order.

Let me know your opinion. LPFR 13:54, 12 September 2006 (UTC)

Agreed, that would be an improvement. (but "Antenna types" rather than "Antenna models" ?) --catslash 14:08, 12 September 2006 (UTC)

I like wiki for aiming higher than most amateur stuff I have read in that it is written and ordered according to physical principles and not to the price anno 2006 or filled with gibberish of clueless marketing guys. For example WiFi is just moving to phased arrays. And some people need to understand that directivity gain has more in common with radiation pattern than with impedance. Arnero 17:15, 12 September 2006 (UTC)

It is positive to talk of all types of antenna form simple whip to phased arrays. My suggestion is not to give the actual prices but just to tell if an antenna is of low or high cost (independent of time). After all the cost criteria is important for most of the people. LPFR 07:20, 13 September 2006 (UTC)

I'm not convinced any discussion of cost (relative or actual) is appropriate here, as cost is more a factor of who made it than what kind it is. --ssd 14:58, 19 October 2006 (UTC)

Agreed. I know this is a huge challenge, but hopefully each section will be understandable by laymen; experts have textbooks on the shelf. Maybe we can do this step by step. First step is the massive re-org. No dissenters? Someone? please take action! John 15:08, 10 August 2007 (UTC)

$120\pi$ or $Z_{0}$ ?

Most (all?) of the formulae on this page use $120\pi$ for the impedance of free space $Z_{0}$ . This is a very common convention to be sure but...

It's not numerically exact. It comes from $Z_{0}={\sqrt {\frac {\mu _{0}}{\varepsilon _{0}}}}=\mu _{0}c$ , where $\mu _{0}$ is the permeability of free space, and by the definition of the SI Amp $\mu _{0}=4\pi 10^{-7}$ H/m (exactly). Then putting the speed of light $c=300000000$ m/s (approximately), so $Z_{0}=120\pi$ (approximately). But $c=299793000$ m/s is closer, so $Z_{0}$ =119.917 $\pi$ is better.

The units are wrong. $120\pi$ is a pure number, whereas $Z_{0}$ has units of Ω, so the units of the various formulae don't come out right.

It obscures the fact that the formulae relate to what (at least in the SI view of things), is a universal constant of nature.

So, if nobody objects in the next couple of weeks, then I may go through and change $120\pi$ to $Z_{0}$ --catslash 14:19, 14 September 2006 (UTC)

You are right. The exactitude argument is not very important for antennas but the units argument is a killer. I will correct the formulas. LPFR 16:53, 14 September 2006 (UTC)

Unfairly

I wrote Those elements are called – unfairly - parasitic elements. I wrote "unfairly" because their usefulness does not deserve the pejorative name of "parasitic". If the name had been chosen in a recent past, they would have probably been christened "slave" instead of "parasitic". User Heron erased "unfairly". Although I appreciate his (or hers) English corrections, I think that this time it was a wrong correction. If the word "unjustly" is better than "unfairly", I agree to the replacement. For the time being, I reset "unfairly". LPFR 12:07, 16 September 2006 (UTC)

I don't think parasitic is a pejorative here. Adding a parenthetical "unfairly" or "unjustly" breaks the flow of the sentence and obscures the important meanings with irrelevant minor details. I don't think the feelings of those poor parasitic elements will be greatly hurt much by ignoring this issue. --ssd 15:01, 19 October 2006 (UTC)

In this phrase, "unfairly" had a physical (or electrical) meaning. As neither Heron nor ssd seem to understood this. I put this meaning in a separate sentence. LPFR 08:03, 20 October 2006 (UTC)

"Unfair" is not a technical term, and in this context, has no meaning. Your added sentence, while still not technically meaningful, at least didn't disturb the flow of the previous sentence, and gave me some insight as to what you were trying to say. I think the usefulness of parasitic elements is sufficiently covered elsewhere in this article, but I have duplicated it at this spot as well. --ssd 18:21, 8 April 2007 (UTC)

Human body as antenna

I would very much like someone to add why when I touch an antenna with my hand the signal gets much louder and clearer on a VHF radio. Can that be put in the article about how/why this happens and why the body is so go and being an antenna etc. Thanks JulianHensey 21:00, 2 December 2006 (UTC)

Your body is an electrical conductor (not a good one, in fact). When you touch the antenna, the result is the same as to lengthen the antenna with a length of wire. In MW, all antennas are always too short and a long antenna works better than a short one. Your body is not an antenna, but it can be used as an antenna, a conductor and even as a heating resistance (but this last utilization is not recommended). LPFR —The preceding unsigned comment was added by 90.2.204.70 (talk • contribs) 07:58, 3 December 2006 (UTC).

While the above is true, there is a bit more to it than that. Many radios, especially hand held radios, use only half a dipole as their antenna. The other half of the dipole exists as an image in the ground plane. By holding the radio, you are extending the ground plane of the radio beyond its case and into your body. Many handheld radios are designed with this in mind, and work best when held. Transmit power for these devices is nearly always less than 5 watts, and thus is safe. --ssd 18:25, 8 April 2007 (UTC)

Computer external antennas for wireless connection

I have removed the following paragraph because I think it is inappropriate for this article. It needs to go in an article on coax connectors or an article on WiFi. --ssd 06:01, 26 August 2007 (UTC)

The most common external connectors for IEEE 802.11/WiFi antennas are reverse polarity SMA, MCX, and in laptops or other small form-factor devices, MMCX. Home-made antennas (colloquially referred to as cantennas) typically use N connectors.

Merging Antenna measurement with this Article

After reading (and writing some parts) of both articles, I think we should consider merging them. The explain the same concepts and are so closely related... Should it be a stub?

Germ 22:46, 8 August 2007 (UTC)

More the other way around, seems to me. This article is already quite large (See WP:SIZE) and the measurement article is not tiny. I'd rather see portions of this one shortened to summaries and their meat broken out into new articles such as a RF polarization one. Jim.henderson 21:26, 9 August 2007 (UTC)

While I agree the article is too long, I think removing the sections entirely is not good either. I've at least added a link to the measurements article. It would be nice to leave a one sentence description of each of the parameters here. I hope you're not done with your transfer. (Please continue the good work!) --ssd 13:52, 12 August 2007 (UTC)

You seem to have abandoned the cleanup, so I have started working on it a bit. I have put back short blurbs for all the parameters -- if you are going to remove those, remove the entire parameter section, and make sure there is ONE article that at least lists it all. I also have started shortening all the parameter sections, moving any long math either to Antenna measurement or a page specific to that parameter. If someone else happens by and wants to shorten things more, feel free. For instance, the section on gain could probably be shortened a bit more and reduced to a single paragraph. (I might do this later if someone doesn't beat me to it.) --ssd 05:07, 26 August 2007 (UTC)

Please continue removing the highly technical parts of this article and the math. It has become unusable as an encyclopedia article; it is too much like a text book. An outline has been proposed (above). Can we us it or fix it to limit the scope of this article? John 05:37, 26 August 2007 (UTC)

Not sure what you mean. I"m not changing the scope of the article, just summarizing long sections that have been split out. None of the outlines proposed above are suitable -- either they already describe existing article structure, or they are poor, or they leave out sections that were added afterwards. --ssd 05:44, 26 August 2007 (UTC)

I am suggesting we change (reduce) the scope. I think we could do a nice job on a narrow scope instead of doing everything poorly. This article is no longer readable. Can you suggest an outline that can be used as a guide to remove entire sections? John 04:26, 27 August 2007 (UTC)

I think the outline of the current article is fine. I think the math sections (which are mostly relocated now) made it less readable, and a few sections probably could use rewording, and there are still a few trailing sections that could be better integrated, but I think the core of this article is fine. What parts are you having trouble reading? --ssd 05:34, 5 September 2007 (UTC)

After reading the current version of the article, I don't think we need an outline to justify removing sections. I think some sections appear to have been dumped here without any context, and their relevance needs to be explained and related to an an antenna. Also, some sections are still too technical (and long) and might be better in their own article, but I'm not up to splitting them out into complete articles. --ssd 06:08, 5 September 2007 (UTC)

I have been away for a while, and am pleased with the work! Good work ssd! I think Mutual impedance and interaction between antennas should be a separate subject...

Germ 23:25, 6 September 2007 (UTC)

Too many antenna models

I think the number of antenna models listed here has gotten out of hand. I said I'd weed it out in 2006... I just created an article for loop antenna, so now everything is covered. I'm going to trim all the non-basic ones now. --ssd 07:40, 26 August 2007 (UTC)

Do we even need to address antenna models? John 04:29, 27 August 2007 (UTC)

Just the basic ones. That's why I moved the rest out. --ssd 05:36, 5 September 2007 (UTC)

Navbox

I found the navigation between the different articles on Antenna a little confusing and thought that maybe adding the box Template:Antenna_Types to this article and other articles on antenna types might help:

Mgoerner (talk) 22:16, 8 June 2008 (UTC)

Mgoerner, That's a very good idea!! --Ŧħę௹ɛя㎥ 19:43, 19 July 2008 (UTC)

Fractal Antennas

I saw the PBS TV show Nova recently about fractals, and they mentioned that certain cell phone antennas are now based on a fractal design. The idea was that a fractal shape allowed a very small antenna to operate over a very wide range of frequencies. I thought someone might want to mention this in this article. CosineKitty (talk) 02:08, 13 November 2008 (UTC)

Fractal antennas are those based on fractal design as mentioned. It should be noted that this antenna is not inherently broad band, although it is marketed as such. Due to the complex current distribution, one may notice multiple points of resonance, which is clearly seen when viewing the following paper: [[4]]. Georgia Tech is working on designs that many mistakenly refer to as fractal, where in fact they are antennas that have undergone genetic algorithm or particle swarm algorithm type optimization. In the antenna world, there tends to be trends as in any other field of expertise that do not fully pan out to the promised characteristics. Fractal antennas is one of these fields. It is also note worthy to mention that fractal antennas and their efficiency rely heavily on their feed point and structure. Wallace (talk) 18:22, 30 October 2009 (UTC)

any LC circuit

why does one need to work around the antenna stuff, a simple LC coil circuit suitable tuned and suitably amplified should do the trick right? I mean if I simply take a simple LC circuit and feed it lot of power and send out a sine wave at a particular freq, it anyways covers a large area. —Preceding unsigned comment added by Alokdube (talk • contribs) 07:59, 6 April 2009 (UTC)

This may be correct, yet what is the efficiency? What is the directivity? This is all based on how we match from our transmission line to free space or the surrounding environment. Wallace (talk) 18:25, 30 October 2009 (UTC)

Antenna element length

Okay many antenna's are 1/4 of the wavelength; but it says a more efficent design is to be one half. What if the elements were the full length of the waves being received; how well would that work? Daniel Christensen (talk) 19:07, 10 November 2009 (UTC)

It greatly increases the feed impedance. The should be a graph somewhere that shows how imput impedance varies with length of element, but the article is already very big, so we may need a new article on the whole topic. Graeme Bartlett (talk) 20:35, 10 November 2009 (UTC)

There are ways to feed a full wave antenna to deal with the high impedance. Once this is accomplished, the effect will be to have a stronger signal perpendicular to the element, and consequently, a weaker signal in other directions. --Jc3s5h (talk) 22:00, 10 November 2009 (UTC)

So, it would be more directional, and more "powerful" in it's strongest direction and weaker in all other directions. It would be better, right? Daniel Christensen (talk) 23:12, 10 November 2009 (UTC)

It depends. If it is, say, FM radio, and a vertical antenna, then signals near the horizon, which is where the FM stations are, would be stronger, so that's good. If it is a horizontal antenna for TV, and the signals are around the same frequency, then the full wave would be better if all the stations are in the same direction, or if you have an antenna rotor. If the stations are in several different directions and you have only one antenna and no rotor, you might be better off with the half wave. --Jc3s5h (talk) 04:38, 11 November 2009 (UTC)

But for the best of the best for me trying to get all the crazy farthest stations just to say I got them a full wave would be VERY directional and work the best for that one-at-a-time game? Daniel Christensen (talk) 00:47, 12 November 2009 (UTC)

If you are talking about TV, then the easiest way to proceed is to buy a deep fringe model. Or if you ahve a lot of space build that stacked rhombic, but that is not steerable. The Yagi is the easiest to rotate. Graeme Bartlett (talk) 12:22, 12 November 2009 (UTC)

Wiring

How are all the elements of a multiband antenna such as a television antenna connected? What would be some of the major mistakes I'd make if I tried to make my own? The impedance would probably be God-knows-what for one thing. Daniel Christensen (talk) 23:12, 10 November 2009 (UTC)

There is modeling software yaginec around that can calculate different arrangements gains and impedance.[5]. A vaiation of Numerical Electromagnetics Code. You need a signal combiner if you use more than one active element. Parallel connection is easy. Graeme Bartlett (talk) 12:33, 12 November 2009 (UTC)

Aerial made of multiple "rabbit ears"

What if I made a television antenna out of a bunch of rabbit ear antennas cut and/or adjusted to the right lengths; wouldn't that be better? Aren't they more anodized becuase they get adequate reception with just ONE dipole versus a whole directional apparatus? What if I formed an aerial just like a regular one just formed out of a bunch of rabbit ears. Done right wouldn't it kick ass? 192.156.234.170 (talk) 23:27, 11 November 2009 (UTC)

One rabbits ears is about as good as one dipole, so your average yagi antenna is better. Graeme Bartlett (talk) 07:53, 13 November 2009 (UTC)

Resonance?

As I understand it, antennas are basically always or nearly always driven in resonance. The article is very coy about this. It talks about the bandwidth, and the resonant frequency, and the gain (directional), but it never actually bothers to tell you why they drive it at resonance; and no I don't think it's just low impedance ;-), you actually get more volts and more magnetic field this way and this causes a bigger E-M field. In other words, in the transmitter antenna you get higher current and voltages than you put in- because it's *ringing*. At the receiver you get much higher voltages than the E-M wave has, because it resonates. This is the key invention that makes it all work. Am I wrong?- Wolfkeeper 03:43, 14 November 2009 (UTC)

A resonant antenna does indeed make adjustment of the transmitter and matching network less critical, and allow components in the transmitter and/or matching network with lower ratings. However, if there is a need for a great deal of frequency agility, it may be better to use a non-resonant antenna and a more robust transmitter or matching network. Jc3s5h (talk) 03:54, 14 November 2009 (UTC)

But isn't that just a question of degree? It's still resonant, just lower Q.- Wolfkeeper 04:10, 14 November 2009 (UTC)

If the antenna is far from resonant then it can be very reactive, appearing as a capacitor or inductor. These items store energy in the form of electric or magnetic fields instead of radiating it. A matching network has to store al;l this energy for each cycle of the RF. Far off resonance will have this energy far exceeding what is transmitted, so you will need extra efficient components, eg a copper pipe instead of a thin wire to cut the loss due to current, or have smooth raound surfaces with no sharp bits when the voltage gets into the tens of thousands of volts. If the antenna appears resistive, the transmitter can jsut drive all its energy into the antenna and have it transmitted. For receive if you don't match, the energy will bounce back out and not go into the receiver. Graeme Bartlett (talk) 07:54, 14 November 2009 (UTC)

No, by definition, the feed point impedance of a resonant antenna is purely resistive, and has no capacitive or inductive reactance at all. In practice, small amounts of capacitive or inductive reactance are ignored to the extent a transmitter designed to drive a resistive load does not encounter any problems. --Jc3s5h (talk) 17:12, 14 November 2009 (UTC), clarified 18:36 UT

Careful here, that's only as seen from the amplifier. The antenna has a great deal of inductance and capacitive ~~impedance~~ in fact, and the voltages and currents it generates as the energy sloshes between capacitance and inductive modes is what makes the antenna radiate strongly. This is the thing that's missing from the article.- Wolfkeeper 18:22, 14 November 2009 (UTC)

Exactly, so me not being an expert on antennas I didn't know that, matching networks make a whole lot more sense now to me. In a sense the matching network is almost part of the antenna. Anyway, my point is, that needs to be in the article, it skirts all the way around it, like it's some kind of lacuna; the high voltages/currents at resonance is what makes the whole thing work at all.- Wolfkeeper 15:30, 14 November 2009 (UTC)

Television antenna

So, how about that article; I was unsure of even creating it in the first place; but it has become quite a good article. The problem still just as much exists with the staggering length of this article, though, because even though all sorts of articles exist on each type of antenna and such; most of the context is still kept here in the sections of the same name... Daniel Christensen (talk) 08:10, 19 December 2009 (UTC)

Image gallery

I added a gallery of images of different antenna types. Its pretty bad; there don't seem to be many simple representative images of common antenna types (dipole, whip, ground plane, yagi, log periodic, long wire, horn, etc.) out there. Maybe someone could find (or photograph) some. --Chetvorno^TALK 00:11, 10 January 2010 (UTC)

Log periodic antennas not mentioned!

Hi, I'm noticing that among other shortcomings, this article completely fails to mention log-periodic (ultra broadband) antennas. EVEN THOUGH there is a WP article on Log-periodic antennas (which isn't real great and doesn't even mention their frequent use in directional UHF TV antennas). I will try to add at least a mention of them when I edit this page, but I am no expert on them so if someone else is they should help out (and moreover supplement the article on them). Interferometrist (talk) 16:46, 23 February 2011 (UTC)

Actually I see now that it was mentioned twice in the article. Could still use expansion. Interferometrist (talk) 18:14, 23 February 2011 (UTC)

Recent (and further) changes

The change to the 2 sentences in the lede about aperture antennas by user:Chetvorno in order to be clearer to non-technical readers was probably justified in that regard, but still has a few problems. First, a horn doesn't exactly involve "reflections" (well, it only says "reflecting surfaces", aka conductive surfaces, which is correct but implies reflection rather than guiding an EM wave) as a parabolic reflector certainly does. Differentiating between transmitting and receiving in that sentence makes it a little clumsy and contrary to my intent to describe an antenna as something which couples the transmission line to the electromagnetic field, rather than as something which does two distinct things. Please don't be offended that I am editing it further (and don't hesitate to improve it further yourself, of course).

Also, on a different subject, the 3rd paragraph in the Terminology section doesn't belong there. Either that section should define a bunch of different terms, or just the term "antenna" with other terms defined as they are later introduced. In that case, this paragraph needs to go somewhere else (I'll work on that if no one else does). Interferometrist (talk) 13:25, 26 February 2011 (UTC)

I'm not offended, have at it. But here are my views. I feel the intro has to back up and come at the subject in a simple way. Nontechnical readers won't know what a "wavefront" is. The new description of what dishes and horns do is vague and misleading (sounds like the "electrical connection" shapes the wavefront). I think the previous description, of some antennas having "reflecting surfaces that collect the radio waves" is a good concrete image to use, distinguishing these antennas from the linear element antennas that are most directly described at the beginning of the paragraph. As you say "reflecting surface" doesn't technically describe a horn antenna, but this isn't a technical description. I agree the differentiation between receiving and transmitting action in my sentence seems clumsy to a radio engineer, but for elementary readers who don't know about reciprocity receiving and transmitting are separate actions that have to be described separately. --Chetvorno^TALK 23:10, 26 February 2011 (UTC)

I understand your point: the lede must be readable by the general public and the rest of the article can become more technical. Perhaps, as you say, it would be better to talk about "reflection" after all, but only mention parabolic reflectors in that paragraph and ignore horn antennas until later in the article. I'm tempted to mention the equivalence with a focusing optical system, but I'm not sure if the "average nontechnical reader" would be so familiar with a reflecting telescope either. I'll try to think of some such wording (unless you get to it first!).

On a different subject, there are a bunch of different photos of various antennas, obviously added by different editors at different times, and at rather irregular positions within the article. Some of them (particularly the ones at the bottom of the article) cannot be appreciated without clicking on the full sized image (or are they only meant to be thumbnails in that regard?). Some are extremely common antenna types, others not (but should still be included to illustrate the variety of possible antennas!). I think for starters, there should be 2 or 3 photos at the top showing the most typical antennas, perhaps a whip antenna, a TV or FM dipole (or "rabbit ears") and a parabolic reflector. And then remove some of the duplication (but I just hate deleting perfectly good material that someone worked to add to the article!). The 2 diagrams thumbnailed under "Diagrams as part of a system" I don't find very useful (whereas there are some other diagrams that should be included). Anyone interested in reorganizing the photos? Interferometrist (talk) 12:44, 27 February 2011 (UTC)

Alright, I went ahead and changed the photos in the earlier part of the article. The ones toward the end I haven't touched. Interferometrist (talk) 20:05, 28 February 2011 (UTC)

In anticipation of further work on this article, I went ahead and tagged as ^{[citation needed]} a number of claims that were dubious or which might have some validity but not in the form they were written. Please reply here if you have anything POSITIVE to say about the validity of any of them. Also there are quite a few other errors in the article that I didn't even bother tagging because I don't want anyone to waste their time looking for references for what I clearly see as invalid or worded so badly that it's mainly misleading. But I'll list the sections/paragraphs involved here so if anyone listening was responsible for writing these or has strong feelings about the issue we can discuss the matters before my rewrite.

Section: Resonant frequency:
- "the power radiated by the antenna is maximum at the resonant frequency."
- "The length referred to .... is the physical length divided by the velocity factor"

Section: Impedance. First 3 sentences.

Section: Polarization. Many problems.

Section: Transmission and reception:
- "Impedance, however, is not applied in an obvious way; for impedance, the impedance at the load (where the power is consumed) is most critical. For a transmitting antenna, this is the antenna itself. For a receiving antenna, this is at the (radio) receiver rather than at the antenna."
- 4th and 5th paragraphs (noise in reception)

Interferometrist (talk) 20:51, 28 February 2011 (UTC)

needs disambiguation and expansion

I came by here to add some material about arthropod antenna. But I noted in passing that the discussion of radio antenna focuses pretty much entirely on low-medium-high frequency resonant wire antennae. It seems to me that some additional material on the isomorphy between lenses, reflecting antenna and wire antenna might be appropriate as well as some mention of non-resonant travelling wave antennae like the Beverage and resonant magnetic field antennae like the ubiquitous medium wave tuned loop.

I might come back sometime and do the loop part which I understand. I'm not the right person to do the rest -- DJK

Why don't you start out by explaining that an antenna is an energy conversion device. You put in AC electrical current, you get out electromagnetic radiation, (and vice versa). Whatever happened to the vertical ground fed quarter-wave length "Marconi antenna" comparison with the horizontal Center fed half-wave AM antennas as a basic concept set?WFPM (talk) 03:49, 14 March 2011 (UTC)

Inaccurate definition

The opening statement that antennas convert electromagnetic waves to/from "electric signals" does not make sense. "Electric signal" is physically the same as "electromagnetic field/wave".

Antennas are coupling/transition devices that scatter free-space electromagnetic radiation modes into waveguide/transmission line modes, and vice versa. Assuming linear behaviour, antenna characteristics are determined by the overlap integrals (scalar product) of guided and free space modes (see scattering matrix, S-matrix).

Antennas need not even be constructed from conductors (as suggested/stated in the article). What is really needed to shape the electromagnetic modes is some structure/material with electric or magnetic susceptibility change relative to the environment at the operating frequency, which does not imply that a material has to be conducting. —Preceding unsigned comment added by 192.122.131.20 (talk) 08:57, 23 March 2011 (UTC)

I think your first point is well taken. The term "electrical signal" is a little ambiguous; I think it could be changed to "electric current", which is more concrete. However, I feel your other suggestions are way too technical for the introduction, although they could be added to the body of the article. The introduction has to be understandable by the general (nontechnical) reader. It needs to back up and define "antenna" in very simple, concrete terms, which the existing intro does pretty well, although it could be improved. Virtually all antennas use metal conductors. Take a look at how other general encyclopedias introduce technical subjects. Content like yours is the reason people complain that Wikipedia articles can only be understood by the people who wrote them. --Chetvorno^TALK 11:34, 23 March 2011 (UTC)

I understand the concern, but I have already been convinced that using overly technical language in the lede is unwise (and against WP guidelines) especially for an article that's likely to be read by the general public. On the other hand, I was always uncomfortable with the word "transducer" in that paragraph, since arguably the antenna only transforms the electromagnetic wave inside the coax (though most of us only think of the current and voltage) into a wave in free space, as you are pointing out. I am changing that paragraph slightly, but this doesn't have to be the final version. There is some overlap of the new first paragraph with language in the second paragraph, but I don't think that the old version of the first paragraph had any useful content that I removed. But if so feel free to edit (or even revert). Interferometrist (talk) 15:22, 23 March 2011 (UTC)

Well now I reworked the second paragraph too, and added a more basic (too basic?) description of electromagnetic radiation. The lede is now significantly longer, but probably not too long for a long article. Of course, any improvements to the wording are encouraged. Interferometrist (talk) 23:26, 23 March 2011 (UTC)

I'm sorry, Interferometrist, I had forgotten our discussion in the previous thread and repeated a bunch of stuff I said in my Feb 11 post there (Alzheimer's?). Also, my post above was abusive and disparaging; I apologise. You've been very courteous about asking for comment; my reply was not. In general I like the improvements to the first para, although I think the lead sentence is a little abstract; my inclination would be to just remove "transducer" from the original lead: something like "An antenna is an electrical device that converts a radio wave to an electric current, or vice versa." Also, the nontech reader may not know that the term "electromagnetic wave" in the 2nd sentence means the same as "radio waves" in the 1st; might put "(radio wave)" in the 2nd sentence. I'd also remove the word "same" in the 3rd sentence. Cheers. --Chetvorno^TALK 15:38, 24 March 2011 (UTC)

Alright, you mean your Feb 26 post (and no, you don't have Alzheimers, just too many WP tasks to keep them all straight :-) and in any case 192.122.131.20 hadn't read that, nor am I offended by repetition. You don't need to apologize for your slightly testy response either, since you aren't generally that way (we all have our moods), and I notice that 192.122.131.20 has been busy editing other articles so you haven't scared him away or anything! ;-) And as far as your original response to 192.122.131.20, I basically agree, and will point out that definition of antenna isn't the point of the article, but rather to describe and explain them. In fact I don't know that there is a really good definition of antenna, but one as broad as anything that couples EM modes (and can be described by an s matrix) is practically pointless. I inserted the qualifier "typically" when talking about conductors as antennas, which one could hardly argue with.

As far as the latest wording, I find it hard to put myself in the position of a person who knows nothing except the general shape of his TV antenna and goes to look it up on WP so I appreciate your (and other's) feedback. Are you saying that the earlier wording of the first sentence is more accesible, and that you would only change the word "transducer" (as I felt a need to)? Mainly I just combined the 2 first sentences of the previous version into one (and then changed a lot more as one thing led to another!). Do you think using the word "couples" is more opaque than writing out "receiving" and "transmitting"? Is "free space" clear to the average reader? Any opinions on the most appropriate wording of the first sentences (and the content of the whole lede) is welcome. Interferometrist (talk) 20:44, 24 March 2011 (UTC)

Also, earlier versions had started only speaking of "electromagnetic waves" and only later saying "electromagnetic radiation of radio frequency, that is, radio waves." Do you think I should stick to one or the other in the first few sentences, and make the connection later? Which term is more familiar then: radio wave or EM wave? Interferometrist (talk) 20:55, 24 March 2011 (UTC)

Short antennas are poor performers

This edit is incorrect. Antennas much shorter than a wavelength are very inefficient. The example given in the edit summary, of AM broadcast reception antennas is not helpful. The only reason the inefficiency of these antennas is acceptable is that the atmospheric noise is so great in that band, even after all the antenna losses the atmospheric noise is still greater than the noise of the amplifying device in the receiver. The change also does not allow for the fact that antennas longer than 1/2 wavelength can be very useful. Jc3s5h (talk) 17:13, 4 December 2010 (UTC)

I'm sorry, but I have no idea what specifically you mean by 'poor performer'. AM reception is poor because of interference from various sources, not because of the aerial. I agree that longer aerials, closer to the wavelength could be theoretically better still, but in the AM wave bands, a ~75 metre long aerial is really very, very impractical, and wouldn't actually perform much better. Other aerials which are used for VLF work would have to be even longer, whereas tuned aerial/reception systems for research purposes are a couple of feet across, whereas the wavelength is thousands of kilometres.Rememberway (talk) 17:29, 4 December 2010 (UTC)

This article is about antennas, not receiving antennas. An antenna the size you find in an automobile would be usless for AM broadcasting. That is why, as an example, WTIC in Connecticut has an antenna height of 134 meters.[6] Antennas have the same efficiency whether used for reception or transmission, but the abysmal efficiency of short antennas makes it tricky to use them for transmitting at all, and requires heroic measures to use them for high power transmissions. Jc3s5h (talk) 20:20, 4 December 2010 (UTC)

The article is about BOTH receiving and transmitting antennas, NOT only transmitting antennas. You effectively appear to be claiming that all receiving antennas have to be similar physical length to the wavelength, and reverting all edits to the contrary.Rememberway (talk) 23:21, 4 December 2010 (UTC)

You should read this article. It's not a reliable source, but there are reliable sources linked from it. Receiving aerials which are actively driven or even just tuned actually receive more radio power than untuned ones, but more than that, the more power sloshing about in the aerial, the bigger the effective aerial size becomes. It's not simply that AM radios (for example) need to use more amplification due to their small aerial, it's that they actually suck in far more radio energy than you would expect because the aerials are resonant and so they are retransmitting an antiphase signal that partially cancels out the transmitter's signal in the far field. That cancelled energy is gone- but conservation of energy still applies. That 'lost' energy has gone into the radio receiver.Rememberway (talk) 00:40, 5 December 2010 (UTC)

You can also get similar effects on transmitters, but less so. The transmitter antenna would have to be driven harder (higher voltages and currents) to make up for its short length, and you'll get resistive losses due to that. So it's not used so much. But aerials shorter than 1/4 or 1/2 waves are definitely used sometimes.Rememberway (talk) 00:40, 5 December 2010 (UTC)

I looked around, and it doesn't seem all that uncommon to do this kind of thing. There's no brick wall below 1/4 wavelength, aerials still transmit and receive even at much smaller lengths.Rememberway (talk) 00:40, 5 December 2010 (UTC)

Statements that are not qualified as applying only to receivers must apply to both transmitters and receivers. Also, there is a question of terminology: antennas that are not operated on their resonant frequency are often resonated with a lumped-element circuit, and that circuit is often not considered part of the antenna. If it isn't part of the antenna, it can't make any significant change to the antenna's resonant frequency. Also, the change indicated that antennas should be 1/4 or 1/2 wavelength, but longer antennas can give good results if properly matched to the transmitter or receiver.

If I could be allowed to make a comment that may not be regarded as ill-informed or contraversal: I have neen involved with antenna design since my childhood, an informed Radio Amateur taught at my school. at the age of 12 I was encouraged by this man to learn more about this subject. An after school project class involved building crystal sets to our own physical designs. (matchbox radio).

First practical experience with "loaded" and "capacity hat" design allowed me to have a very efficient end fed aerial for 160 mtrs (1500khz long wave) in my short back garden. This knowledge allowed me to design and build my own efficient hand held VHF transmitters in the 1970s.

When CB Radio was legalised in the UK in 1980 I exploited a gap in the market place to introduce a commercial "legal looking" antenna. This was an "near end loaded" design, it left a substantial metal section beyond an inductance resonating at frequency which allowed the physically shortened aerial to behave as if it were a full 1/4 wave in length. Another innovation was the inclusion of a Balun to accurately match the feed point impedance to the coax (unbalanced) feeder. My design sold in quantity in the CB market place. Most Ham (Amateur operators usually made their own aerials at this frequency.

So, in summary, it is correct to assume that any radiator which is less than 50% of a quarter wave length will be hopelessly inefficient. Base loaded or centre loaded designs included. Marconi quarter wave (earth counterpoised) is the poorest design for ground wave propogation, vertical dipoles at at least one half wave length above the ground are preferred.Francis E Williams (talk) 20:26, 5 December 2010 (UTC)

I am planning to write an article on Chu-Harrington limit which is about the small limit for antennas. Graeme Bartlett (talk) 13:15, 25 March 2011 (UTC)

That would be splendid. I don't know what the Chu-Harrington limit is, but it would be great to have a clear explanation of why antennas must sometimes be rather long, that could be understood by zoning boards, administrators of buildings on which antennas are placed, and the like. Jc3s5h (talk) 14:17, 25 March 2011 (UTC)

I wasn't watching this page at the time of the earlier discussion, but I will lay the issue out quickly. Although I note that the conclusions we reach here have no apparent ramifications on the article as it currently stands. If anything the conclusions would belong in section 4.5 "efficiency" because that is the nub of what we are discussing.

Everyone knows that a dipole consisting of 2 1/4 wave sections, or 1/4 wave vertical antenna + ground, performs nicely and making it much longer isn't very useful in most respects (except for a little more broadside gain). But there are two completely different problems involved here which easiliy get confused.

1) First there is the issue of the driving point impedance. A pair of elements which are a little shorter than 1/4 wavelength (or 3/4, 5/4, etc.) happen to have a purely resistive driving point impedance (seen at the terminals), 73 ohms as we all know for a 1/2 wave dipole for instance. As the length changes from that point the reactive component of DP impedance rises sharply (more so when the conductor diameter is very small compared to its length). That does not make the antenna "bad" per se, it means that an appropriate matching network is needed to match it to the transmitter (and transmission line). Making the antenna 20% shorter will create a large reactive capacitance and a typical transmitter/receiver and feed system will be poorly coupled, and you call that "bad". Someone else will attach a "loading coil" whose inductance cancels that reactance, and now the impedance seen is resistive and the antenna is perfectly "good" (though less than 73 ohms).

Whether you want to call the loading coil part of the antenna, or whether you want to call the antenna "resonant" is all symantics. Except for (2) below, you can make an antenna shorter and shorter (or longer), match it to the line, and the antenna will perform just fine, taking into account a slight difference in radiation pattern and a significant (or even huge) difference in the resistive driving point impedance seen after introducing a series inductance (loading coil) or other reactance cancelling technique. In particular, the effective area of an antenna in receiving (that is, how much of the power of an EM wave it intercepts and might or might not deliver to the receiver) is always equal to lambda^2 / 4 pi when averaged over all solid angles. This is true regardless of its shape, size, or what color you paint it :-)

2) Now the issue of more importance in this discussion has to do only with efficiency (as it is properly defined in the article: "Mathematically, efficiency is calculated as radiation resistance divided by total resistance."). If the antenna were made of a perfect conductor, then it would be 100% efficient and any size antenna if properly matched would perform nicely. The antenna driving point impedance would be equal to the radiation resistance R_r + jX where X can be cancelled out with a loading coil, for instance. All of the power delivered to the antenna (using a matched transmitter) would be radiated. Unfortunately antenna conductors are rather resistive at RF particularly due to the skin effect, and this reduces the efficiency: if the ohmic resistance (as seen at the terminals) is R_loss, then the transmitter sees R_r + R_loss + jX and the efficiency drops to R_r / (R_r + R_loss). In a dipole R_loss can be much less than 73 ohms, so the efficiency can be (usually is) high.

But here's the problem. As you make the antenna shorter, R_loss falls linearly with that length, whereas the radiation resistance R_r falls MUCH faster (not a simple equation at all, given by the solution of Hallen's integral equation). So because of, and only because of R_loss, the efficiency of an antenna in practice falls rapidly as the element gets much shorter than lambda/4. I should also point out that even if the antenna itself had R_loss=0 (impossible) you would still have the ohmic loss of the loading coil (or other matching network components) in series with R_r. Or in the case of a small loop, the loss in the resonating capacitor. So it is ultimately the rapid fall in efficiency that makes "short antennas poor performers." There is no magic about it.

Finally, as referred to above, there are silghtly different criteria for transmitting and receiving antennas. Although all of the properties including efficiency apply to both, an inefficient transmitting antenna loses power and requires a stronger transmitter to produce the same external field. In a receiving antenna, loss of efficiency may or may not matter. In particular, at lower frequencies (MW) the received noise level is never set by the receiver noise but by ambient EM noise (static) so reducing the signal and THAT noise together doesn't hurt the received SNR. But at UHF where the receiver noise may be dominant, the loss of efficiency lowers the received SNR. This is covered well in Loop antenna#Small loops where someone added a very useful graph of ambient noise relative to kT. This shows why the small (and VERY inefficient) loop antenna in an AM broadcast radio works as well as the guy who hangs a 100 meter wire out his window. And at very high frequencies where a short antenna DOES hurt reception, the wavelength isn't so large anyway so making a 1/4 wave antenna isn't something so huge to begin with.

Good, now that I laid that all out, I'll have to work it into the article :-) -- one of these days. Interferometrist (talk) 18:29, 25 March 2011 (UTC)

Invalid reference to "velocity factor"

A recent edit cites a reference regarding the difference between an actual half wavelength and the length of a resonant half-wave dipole. Unfortunately I don't have that book nor can I access it on the google books page. But I know there is a lot of misinformation circulating about a so-called "velocity factor" accounting for the shorter length of a dipole element, which is erroneously repeated in this section of the article, and which is totally invalid. There is no such thing. A half-wave dipole has a feedpoint impedance which is partly inductive: 73+j43 ohms. To make the impedance resistive, one reduces the length of it by about 3% (depending on the diameter of the conductor). "Velocity factor" is a termed correctly applied to transmission lines using a dielectric, but was erroneously picked up by amateurs working with antennas. I will correct that paragraph sometime, though I'd like to know what the "Mobile Handset Design" reference says, if someone could help me out. Thanks, Interferometrist (talk) 17:01, 6 April 2011 (UTC)

I believe it is referred to as "velocity factor" in some sources: 1 2 The difference between physical and electrical length in antennas and transmission lines is due to the same effect, right?, a reduction in propagation velocity below the speed of light. In the half wave dipole you mention, the presence of nearby structures 3, and end effects 4 reduces the impedance below the impedance of free space, 377 ohms, resulting in a slightly lower propagation speed in the elements, so the antenna needs to be slightly shorter for resonance. You can consider the antenna elements as transmission lines, with their "shields" (the ground and other structures) very far away, which is why the velocity factor in thin-element antennas is usually close to 1.0, as you mention. --Chetvorno^TALK 22:02, 6 April 2011 (UTC)

Well, no. Actually almost everything you said is wrong, but I don't fault you as these are common myths that get repeated and repeated. I haven't looked at your sources yet, but I will look at the ones I can access online, but I really don't expect to learn anything new from them. Transmission lines have a velocity factor which is 1/sqrt(eps) <<< the relative dielectric constant in between the conductors (or modified by the "fill factor" when the dielectric doesn't fill that region completely, as in twin-lead). Antennas exist in free space or air. (An antenna inside an actual dielectric WOULD have the same velocity factor, but that isn't the issue). The current pattern on a dipole results from the difficult solution to Hallen's integral equation and the standing waves on dipole elements (assuming length >> diameter) are at the free space wavelength. It cannot be solved in the manner of a transmission line (in which case the velocity factor would be 1.000 in free space); the resistive part of the driving point impedance is due to the radiation resistance, and the reactive part happens to be inductive at lambda/2 which is why it is shortened slightly to get a pure resistance. Grounds and other metal nearby do not have an effect on the wavelength of the standing wave pattern (but can reflect power and change the impedance seen at the feedpoint). The solution for a dipole doesn't assume any other conductors. Again, I realize what I'm saying goes against lots of folk wisdom, but conforms to the results of antenna theory. I will look at your references though. (By the way, I don't have a copy but do you have the ARRL antenna handbook? See if they have "velocity factor" in their index.) - Interferometrist (talk) 23:12, 6 April 2011 (UTC)

Well I was able to access your references 3 and 4. In a word, they are simply wrong. Interferometrist (talk) 23:16, 6 April 2011 (UTC)

My last response last night was rather hasty. Yes, they were wrong in talking about a velocity factor. Reference 4 was interesting though because it did aggregate a large amount of useful material, but it obviously wasn't written concisely or very thoughtfully. It was full of contradictions that a single person writing it (while thinking about what they were writing) wouldn't have done. It doesn't even appear to have been proofread! But let's look at the pertinent section 1.11.3. Item A) is unquestionable for antennas with a capacitative hat, which had been discussed in that book, but isn't an issue here. Item C) is interesting but also irrelevant. However B) End effects, is interesting and I'm not sure that this isn't a different (or even better) way of looking at the problem; my intuition tells me that it could be so and I will have to analyze this when I have time, though of course that would be OR (I don't think this author simply mentioning it without quantification and without corroboration is a sufficient citation). In fact the length reduction for cancelling the reactance is very dependent on the conductor diameter (I have a nice graph illustrating that, but it's copyrighted), which would similarly affect the "end capacitance" if you will. The explanation for that that I have read is simply that the amount of reactance introduced by a certain length change decreases with increased element diameter, so you need less shortening for a thin element, but in every case that shortening is to compensate for the +j43 ohms of reactance that an exact 1/2 wave dipole has.

However in each of these cases, again, what we are talking about is a change in the required length of a dipole, not a "velocity factor" affecting the velocity of signals travelling along the conductor. In fact you (Chetvorno) supplied a perfect argument yourself why that isn't different from c. Since you propose to view the bare conductor as the inner conductor of coax as the outer conductor radius increases greatly, it should have the same propagation velocity of air-dielectric coax which is = c since the dielectric constant of air =1. Another check on this would be to look at the length of a 3/2 or 5/2 antenna whose feedpoint reactance=0. If an actual "velocity factor" were involved then the length corrections would be multiplied by 3 or 5 (I don't have data on that). Interferometrist (talk) 16:10, 7 April 2011 (UTC)

Ah. Everything you say makes sense. So whenever there's only perfect conductors and vacuum (dielectric constant = 1) the velocity of an electric disturbance along a conductor is always c? Anyway, you obviously know more about this than I, I'll take your word for it. I've learned something. I'm not arguing for the inclusion of the term "velocity factor" in the article; it's used hardly at all with antennas, go ahead and take it out. My only concern is that the distinction between "physical length" and "electrical length" be included, since these are widely used, and in many antennas are very different 1. There are antennas where the difference between physical and electrical length can be attributed to the "velocity factor" due to a dielectric, right, such as the microstrip antenna? BTW, the ARRL antenna book does use the term "velocity factor" in an antenna; perhaps it's just a convenient way to express the difference between physical and electrical length, to attribute it to a lower velocity of the waves, whether that can actually be defined or not? --Chetvorno^TALK 17:37, 7 April 2011 (UTC)

Well, we don't disagree but now it's getting down to semantics. We both understand "physical length" but what does "electrical length" actually mean? If it means "resonant," fine, but you'd hardly talk about the "electrical length" of a 100 MHz tuned circuit being 1.5 meters. So if you make an antenna which is resonant at 100 MHz, which you can do in many many different ways, why do you need to say it has an electrical length of 1.5 meters? Does a 3/2 wavelength dipole about 4.5 meters long (which resonates at 100 MHz) have an electrical length of 1.5 meters? What about when you use it at 33 MHz, is it now 3x longer ("electrically")? As far as I can see the concept of "electrical length" is based on the same confusion as "velocity factor." Or it's just a silly way of specifying an antenna's resonant frequency.

The reference you point to is fine for what it actually says, but saying that a vertical antenna with a "loading coil" at the bottom has an "electrical length" of lambda/4 doesn't mean anything beyond the fact that it is resonant at that lambda. It's impedance is resistive (that's WHY you introduced the coil) but much less than that of a 1/4 wave antenna. Its radiation pattern is slightly different (a little less gain in the horizontal direction). The 10cm loop antenna in my AM radio gets tuned with a variable capacitor: does that vary its "electrical length" from 100 to 300 meters? If one must talk about the loading coil or resonant capacitor being part of the antenna, then yes, the "antenna's" resonance changes due to it. A clearer way of talking about it, however, is to say that the antenna has a certain impedance at frequency f and then you run it through a "matching network" which (in the above cases) transforms it to a purely resistive impedance (or to the actual impedance of the coax, with a more complicated network). Then you don't have to talk about it having an "electrical length" but an impedance which (although purely resistive) is different from that of a 1/2 wave dipole. So that's my view of the SEMANTIC ISSUE.

And you are right that when a transmission line with a dielectric is involved, such as with a microstrip antenna, you do very much take the velocity factor into account, as you would for any travelling wave antenna such as the multi-slotted waveguide antenna (forgot the correct name) whose velocity factor is <1 for a different reason (the TE or TM waveguide mode). And I'm sure there are other examples.

I haven't dealt with "rubber ducky" antennas (though I realize they are commonplace in walkie-talkies) and I don't know if they should be viewed as being vertical antennas with "distributed inductance" or as small ("normal mode") helical antennas, or (most likely) if these are equivalent designations as the article states. Adding a ferrite core inside a loading coil would greatly reduce the resonant frequency of the antenna system, though I had never heard of that applied to a helical antenna. The article is fine in reference to a specific antenna application and technology, but it isn't a source of theory, so I wouldn't expect its terminology to be exact.

I should also mention that the term "effective length" of an antenna is sometimes used, and I have seen two completely different definitions for this term (neither having to do with resonance or "electrical length" in the above context). "Effective area" (or "aperture") of a receiving antenna (as a function of direction) however is a concise and useful term. Interferometrist (talk) 19:02, 7 April 2011 (UTC)

That's an interesting point of view, but it doesn't matter what you or I think about the term. WP:DUE requires that "due weight" be given to all concepts commensurate with their prominence in WP:RS's. "Electrical length" is widely used in the technical literature of resonant antennas; it's one of the first technical terms encountered. We need to tell the readers what it means. They can decide whether it's a useful concept for them or not. --Chetvorno^TALK 02:19, 8 April 2011 (UTC)

Well I think you're mistaken and most of what I said wasn't a point of view, though my contempt for fuzzy/convoluted/misleading concepts may have shown through. What I am saying, in essence, is that this term, "electrical length" is NOT used in antenna theory. In other words it is never concisely defined. And unless I am wrong that is sufficient reason for its deprecation over terms that are used and concisely defined in books on antenna theory (using universally agreed-on definitions). Making that determination is not POV or OR, it is a question of looking at the "reliable references" regarding antenna THEORY. But I agree that this term is used in some publications which may be considered RS in other ways (but not in developing antenna theory) so it should be mentioned, but not given the same weight as the following terms: antenna gain (or power gain, or just gain), directive gain (or directivity), antenna efficiency, driving point or feedpoint impedance (or just impedance), effective area (or aperture). Also, contrary to my earlier confusion, it appears that "effective length" or "effective height" (for a monopole) indeed IS a concise and accepted term, actually TWO terms: effective length of a transmitting antenna and effective length of a receiving antenna, having quite different meanings and rather specialized use so they dont belong in the article (also because they are dependent on the feeding method or matching network, unlike "gain" which is more useful and applies equally to reception and transmission).

Now I have only checked two books on antenna theory (of course there are only a few), one I have on hand (my textbook) and one at the library. But that should be enough because either of these respected books would be quite remiss to omit a basic concept if that is what it were (they surely include the other terms I mentioned, in abundance). However the ARRL antenna handbook IS a reputable source on antenna engineering (if not theory per se) and it isn't available at our library, so maybe you can look at it and see if the term is used and more importantly if it is ever really defined (rather than just used descriptively). If so, I might change my mind (especially if there were a second book on antenna theory which defines it similarly). And it isn't a question of the definition being fuzzy in this case, since there is only one possible definition. It is just a silly way of refering to an antenna's resonant frequency, and that is what I will write in the article (but I will leave out "silly" which you could well call POV :-) . Interferometrist (talk) 17:56, 8 April 2011 (UTC)

I should add, that in checking those books, I cannot find the term in the index (where it certainly would be if it were introduced as a term and defined in an equation) but certainly didn't read through the one library book (> 1000 pages!). The book on my shelf I have read sufficiently that I probably would have remembered seeing it. Interferometrist (talk) 18:02, 8 April 2011 (UTC)

section on resonant antennas misleading/got errors

A lossless center-fed (needs to be mentioned) thin wire, lambda/2 (needs to be mentioned) dipole in free space (needs to be mentioned) has a feedpoint impedance of about 73 ohms, not 63 ohms. The discussion about operating at frequencies 20% above the first harmonic seems to assume that the radiation resistance would be unchanged; in fact it is increasing (the radiation resistance is a function of the ratio wire length/wavelength) - so the feedpoint voltage would go up, even in complete absence of a reactance. Also, the reactance of an off-resonance doublet depends on the diameter of the wire. A statement like "about 150 volts of feedpoint voltage" is meaningless; depending on the wire size, the feed voltage could take an arbitrarily high value. -- wh —Preceding unsigned comment added by 218.186.16.226 (talk) 14:40, 3 May 2011 (UTC)

I believe that the radiation resistance of a half-wave dipole being 73 ohms has been mentioned elsewhere, but this example is for a RESONANT dipole slightly shorter than 1/2 wavelength. So for the sake of the example I took one which has a length to diameter ratio of 1000 which (according to ARRL antenna handbook) is about 2.5% shorter and has a feedpoint impedance of 63+j0. The point wasn't to discuss the numerical details but to emphasize the relation between radiation power and current (regardless of voltage) and the numbers I offered are approximately correct. Yes the radiation resistance goes up (to about 130 ohms) but the reactance increases much faster to about 150 ohms. I can see now that I should have added the 130 to get 200 ohms (thus 200v) so I will change that detail. But yes, 1 amp going into it WILL produce as much (actually more, as you point out) radiated power. My statement wasn't meaningless but was contingent on a length/diameter ratio of 1000 which indeed wasn't stated in the text but was incidental to the example. If my numbers (after this change) are incorrect, please let me know. I want this to be accurate but not with unneeded detail. Interferometrist (talk) 16:18, 3 May 2011 (UTC)

Removal of "Maximum power transfer requires matching the impedance"

The article said Maximum power transfer requires matching the impedance of an antenna system (as seen looking into the transmission line) to that of the receiver or transmitter. But this is just plain incorrect. For maximum power transfer you need to match the complex conjugate of the impedances. For pure resistive loads they are the same, but not for reactive loads. If an antenna presents an impedance of 73 + j 42 Ohms, then for maximum power transfer the transmitter should have an output impedance of 73 - j 43 Ohms. Drkirkby (talk) 23:35, 14 June 2011 (UTC)

Oops, I used 42 in one part and 43 in another. Chose whatever you want. — Preceding unsigned comment added by Drkirkby (talk • contribs) 00:24, 15 June 2011 (UTC)

Remove "An antenna with a low gain emits radiation with about the same power in all directions"

The article stated a low-gain antenna radiated with about the same power in all directions. That's total rubbish. A two element Yagi-Uda array would not be considered a high gain antenna, but can theoretically be produced to have an infinite front to back ratio, and practically 30 dB is possible, which is a 1000:1 ratio of the radiated powers. Drkirkby (talk) 00:15, 15 June 2011 (UTC)

Opposite side lobe

I don't know why anyone has a diagram showing the "opposite side lobe". It's certainly not a term I've ever come across before.

Dave — Preceding unsigned comment added by 213.78.42.15 (talk) 16:10, 17 June 2011 (UTC)

Current produces magnetic field wave, charge produces electric field wave?

Isn't an electromagnetic photon emission produced by the acceleration of electron charge?

124.168.248.197 (talk) 10:17, 10 August 2011 (UTC)

Yes. The current applied to the antenna by the transmitter is not direct current (DC), it is alternating current (AC), causing the electrons in the antenna to move back and forth with a sinusoidal (harmonic) motion, at the frequency of the transmitter. The acceleration and deceleration of the electrons causes them to emit radio frequency photons. Electromagnetic radiation from antennas is usually not described in terms of photon emission (the radio photons emitted by a television broadcasting antenna are the size of beach balls, and have such a low energy, 10^-26 joule, that it is probably impossible to detect them individually), but you're right, that's how it works. --Chetvorno^TALK 11:41, 10 August 2011 (UTC)

Hmm...beach ball sized photons - strange concept. Thanks for being a valuable contributor to my favourite info source.

124.168.248.197 (talk) 17:38, 10 August 2011 (UTC)

Antennas / Antennae

The antennas-for-radio-equipment vs antennae-for-insects distinction is predominantly a feature of American English. It is valid and common in British English to use antennae for either. See this page which includes citations from major British publications.

217.154.131.202 (talk) 12:48, 27 August 2011 (UTC)

Do omnidirectional antennas have gain?

Recently there has been an edit conflict going on over whether an omnidirectional antenna has gain. I thought it would be better to move it to the talk page. This source 1 provides a brief explanation. Gain is defined as the ratio of the far-field power density radiated by the antenna in the direction of its maximum field strength, to the power density radiated by a hypothetical isotropic antenna. An isotropic antenna radiates equal power in the entire solid angle around it, in all three dimensions; its radiation pattern looks like a sphere. Any antenna which restricts its radiation to a smaller solid angle will have gain. An omnidirectional antenna radiates equal radiation in the plane perpendicular to its axis, but its gain drops off with elevation angle to zero on the axis. Its radiation pattern looks like a donut. It doesn't have a unique direction of maximum radiation, but it does have gain. Since the emitted power is concentrated into the "equatorial" directions perpendicular to the antenna, it emits greater power density than an isotropic antenna in those directions. A simple omnidirectional half-wave dipole antenna, whose radiation drops off as the cosine of the elevation angle, has a gain of 1.64, or 2.15 dB compared to an isotropic antenna. --Chetvorno^TALK 19:57, 26 April 2012 (UTC)

Yes the point was that what is called omnidirectional, is only like that horizontally and not in the vertical direction. Extra gain can be achieved by stacking vertically, at the expense of not having gain off the horizontal. Graeme Bartlett (talk) 21:54, 26 April 2012 (UTC)

The actual passage in question was about antennas "labeled" omnidirectional. Since we don't have any source that has reviewed the labels of antennas and compiled the result, I don't think we can say anything about how antennas are labeled. Jc3s5h (talk) 00:31, 27 April 2012 (UTC)

Aerial gain is inversely proportional to acceptance angle, as the acceptance angle goes up the gain comes down, this article on TV aerial polar response diagrams illustrates the point. The only way an aerial has gain (i.e. more than 0dBd signal received) in any particular direction is because it is tuned to have has less than 0dBd gain in the other directions. It is impossible for an aerial (which is a passive device) to have gain in all directions, i.e. an omnidirectional aerial, it can`t happen. --JustinSmith (talk) 17:43, 27 April 2012 (UTC)

The ARRL Antenna Book 20th ed. on page 18-1 states "A VHF net operator may find an omnidirectional system almost a necessity, but it may be a poor choice otherwise. Noise pickup and other interference problems are greater with such omnidirectional antennas, and omnidirectional antennas having some gain are especially bad in these respects." [Emphasis added.] Plainly this book uses "omnidirectional" to mean having equal gain at all points on the horizon. Since this is such a popular source, it's definition of "omnidirectional" cannot be ignored and any article wishing to use a different definition would have to state that definition, and explain the different definition only applies within the article. If you can find other popular sources that treat "omnidirectional" as a synonym for "isotropic" then the term "omnidirectional" should never be used in any article without defining it. Jc3s5h (talk) 18:27, 27 April 2012 (UTC)

I think maybe the confusion stems from the two different units of measurement that are being used here. "Decibels isotropic" (dBi) compares the antenna's maximum signal strength to that of an isotropic radiator, which is equal in all directions and has no "lobes". No antenna can have a gain of less than 0 dBi. "Decibels dipole" (dBd) compares the antenna's maximum signal strength to that of a particular omnidirectiona antenna, a half-wave dipole, which has a torus-shaped "main lobe" with a maximum power radiated in azimuthal directions (perpendicular to the antenna axis). Since it radiates less of its power than an isotropic antenna in the polar directions, it can radiate greater signal strength in azimuthal directions, 2.15 dB more, so dBd = 2.15 + dBi. Since the dBd measure compares an antenna not with the average radiation of a dipole but with the maximum radiation of its "lobe", an antenna can have negative gain in dBd. In fact an isotropic antenna has a gain of -2.15 dBd. --Chetvorno^TALK 19:24, 27 April 2012 (UTC)

Other omnidirectional antennas can have a gain greater than 0 dBd, by radiating their power in a narrower azimuthal angle than a dipole does. They have a radiation pattern that looks like a "squished" donut, with the power concentrated in a narrower angle about the horizontal direction (narrower half power beam width or "acceptance angle", in Justin's terminology). An example is the collinear array. --Chetvorno^TALK 19:51, 27 April 2012 (UTC)

Omnidirectional is (sometimes?) used to indicate equal gain all around the horizon, which is possible for a vertical dipole, but not for a horizontal dipole. Jc3s5h (talk) 21:16, 27 April 2012 (UTC)

Thanks, I think I'm finally up to speed on what this thread is about. An antenna that has a radiation pattern symmetrical about the vertical axis and decreasing to zero on the axis is "omnidirectional"; is it still considered "omnidirectional" if its axis is horizontal? It has the same radiation pattern, but because of its orientation with the Earth it no longer radiates equal power in all horizontal directions. Most sources I found 1 2 3 4 don't address this detail and simply say an omni antenna is one which radiates equal power in all horizontal directions. One widely-used text 5 defines an omni antenna as one with "...a nondirectional pattern in a given plane and a directional pattern in an orthogonal plane." which would seem to imply that an omni antenna is omni regardless of orientation. It looks to me like it's just a matter of definition. --Chetvorno^TALK 23:44, 27 April 2012 (UTC)

Merger or Simplification Proposal

I propose that High-gain_antenna and Low-gain_antenna be merged into Antenna_(radio).

The two HGA and LGA articles do not stand on their own.

The pages are full of content and examples that are much better covered on the Antenna_(radio) and Antenna (Directional) pages. An HGA or LGA is not notable in the way that a monopole-, dipole-, whip-, dish-, or television- antenna is.

However, there are about 50 pages that link to High Gain Antenna, mostly about spacecraft, where HGA and LGA are well known and correctly used. Unfortunately the HGA and LGA pages don't actually point out the important features of the HGA and LGA, they just revise some basic antenna theory, and give examples and pictures.

What do you think is the best way forward? Perhaps LGA and HGA should each be a short stub to capture the links, mention the spacecraft context, and pass the user on to Antenna (Radio) and Antenna (Directional). This would save the maintenance of a content page.

Thomasonline (talk) 06:19, 2 June 2012 (UTC)

I think that this page is already very large, and we should not merge more content. Instead we should be developing those two articles to be more self sufficient on what makes them special, and different from your normal gain antenna. Graeme Bartlett (talk) 12:27, 2 June 2012 (UTC)

Support merger. HGA and LGA don't merit full articles, they just duplicate content in the other articles. HGA and LGA could be explained in Directional antenna. Graeme, on the subject of size, this article is incredibly bloated and wordy. It's size could be cut by 50% and still cover everything better than it does now, and it should be. --Chetvorno^TALK 17:55, 2 June 2012 (UTC)

Reciprocity Section

I don't do this often, but I found a section that is wrong. Before correcting it, I wanted to make sure that I'm correct. Antennas do indeed transmit and receive the same way. It is also possible to add a circulator to the antenna to make sure that the energy going to the antenna does not get reflected back into the final RF stage. There are two problems with the section as written. The first is that the section implies that the antenna includes this circulator. The problem with this is that while you can certainly buy an assembled antenna product with three ports (the third being the actual element itself), this would be viewed as an antenna and a circulator combined in an assembly and then shipped as a product. Electrically, the two could be separated and the antenna would only have one port (well, two, the other being space and the receiving antenna). The second issue is that antennas have to be very linear, as well as their components. In fact, the circulator needs to also be very linear. Non linearity takes a pure tone and generates higher order terms in the Taylor Series (at least this is a useful approximation). When you have two pure tones together their signals can actually mix. When this is from the output of a transistor or the like, then this is called intermodulation. When this is from a passive device (like from a ferrite circulator or a connector, or a rusty bold), it's called passive intermod, or PIM. The thing that makes a circulator work is the additional phase shift due to the ferrite. I'm not going to Pozar to look up the particular derivation, but here's a website detailing how a ferrite circulator works: "[7]". In fact, a ferrite needs to be incredibly linear for all but single tone outputs or spurrious signals will be generated. There are whole classes of non-ferromagnetic connectors which don't contain nickel or any material which has a non-unity relative relative permeability. Twinesurge (talk) 04:46, 10 August 2012 (UTC)

I think this section is just an introduction to reciprocity. It's point is that most antennas are reciprocal but it is possible to make nonreciprocal antennas with nonreciprocal materials like ferrites. Maybe the example of circulators is the wrong one. I think the use of nonreciprocal ferrite phase shifters in phased array antennas is widespread. But I don't think the section should go deeply into nonreciprocal materials, the article is already too long and bloated. --Chetvorno^TALK 15:37, 10 August 2012 (UTC)

The problem is that ferrite materials themselves are reciprocal materials (i.e. the direction the part is inserted does not matter). The difference between a ferrite material (for the purposes of electromagnetics) and a non-ferrite material is that a ferrite has a relative permeability that is not 1, not that you can make energy flow in only one direction. Ferrites can be non-linear if you put too much current through them (you align all the domains and then there is no more alignment possible). My purpose in pointing out the error in the article is that, as a system, the antenna is still reciprocal. The energy still leaves the antenna the same way that it enters the antenna. Put another way, the antenna can be viewed as a transmitting antenna or a receiving antenna (and solved as such) and it will yield the same result. Simply adding an isolator to it does not make the antenna non-reciprocal because the isolator (or circulator) is not the antenna itself. The purpose of the link was to point out that the device was in fact linear as no non-linear effects are being exploited. I also pointed out what the consequences of non-linearities would be (mainly, mixing products). This section needs to be corrected. I will do so shortly. Twinesurge (talk) 22:37, 20 August 2012 (UTC)

Removal of "Reactance diverts energy into the reactive field"

The article said "Reactance diverts energy into the reactive field^{[citation needed]}, which causes unwanted currents that heat the antenna and associated wiring, thereby wasting energy without contributing to the radiated output." The "citation needed" was added 4 months ago, and none has been supplied, so I have removed this. I believe the author is wrong on this. Drkirkby (talk)

I don't know about wrong, but the "reactive field" part makes no sense to me. Non-zero reactance does tend to lead to loss due to resistive heating, though. --ssd (talk) 14:37, 14 April 2013 (UTC)

"fairly thin conductor"

Reference to a "fairly thin conductor" seems inaccurate. The reference should probably be changed to read as "a conductor with zero reactance", or similar. This point seems to become clear by reading through the paragraph. Kernel.package (talk) 22:41, 7 January 2013 (UTC)

Merge High gain antenna, Low gain antenna, and/or Directional antenna?

This section is a central place to discuss various merger proposals for these pages. High gain antenna, Low gain antenna, and Directional antenna are stubs and it has been suggested at least some of them could be merged. Merger tags have been on the first two for some time. I have copied an existing discussion from Talk:High-gain antenna below. --Chetvorno^TALK 15:04, 9 March 2013 (UTC)

Do we really need both Directional antenna and High-gain antenna? A high-gain antenna is just a very highly directive antenna, so maybe this article should be merged into Directional antenna. On the other hand, the latter article could also be merged into this one. --Chetvorno^TALK 08:54, 4 December 2010 (UTC)

The example of a Yagi in the Gallery section, I would call directional but not high-gain as it has a single director. There is also a Low-gain antenna article stub - this may be about antennas which still have an appreciable directivity, but it's not entirely clear. So if any merging is to be done, I reckon it should be into Directional antenna. --catslash (talk) 17:07, 4 December 2010 (UTC)

I propose that High-gain_antenna and Low-gain_antenna be merged into Antenna_(radio), or another simplification made. The two HGA and LGA articles do not need to stand on their own.

The pages are full of content and examples that are much better covered on the Antenna_(radio) and Antenna (Directional) pages. An HGA or LGA is not notable in the way that a monopole-, dipole-, whip-, dish-, or television- antenna is.

However, there are about 50 pages that link to High Gain Antenna, mostly about spacecraft, where HGA and LGA are well known and correctly used. Unfortunately the HGA and LGA pages don't actually point out the important features of the HGA and LGA, they just revise some basic antenna theory, and give examples and pictures.

What do you think is the best way forward? Perhaps LGA and HGA should each be a short stub to capture the links, mention the spacecraft context, and pass the user on to Antenna (Radio) and Antenna (Directional). This would save the maintenance of a content page.

Please discuss on the Talk:Antenna_(radio) page. Thomasonline (talk) 06:25, 2 June 2012 (UTC)

Since Antenna (radio) is already bloated I propose that High gain antenna and Low gain antenna be merged into Directional antenna --Chetvorno^TALK 15:04, 9 March 2013 (UTC)

I have actually never seen "low gain antenna" used as a specific antenna type (rather than just a description) except in the context of spacecraft, where the low gain antenna may be smaller or more robust or something, and the high gain antenna is fragile, large, and needs to have the spacecraft working well enough to be aimed. This kind of information should go in a spacecraft article, not an antenna article. Otherwise, "low gain antennas" are called "omnidirectional antennas" instead. I think the low gain article could be just changed into a redirect without a merge, it is so stubby it almost has no content to merge. --ssd (talk) 14:43, 14 April 2013 (UTC)

I agree about the origin of the terms; I think NASA used the terms "high gain antenna" and "low gain antenna" internally to describe spacecraft antennas, and the terms became popularized when they appeared in NASA press releases and interviews. Nontechnical people have assumed they were standard radio engineering terms, rather than internal NASA buzzwords. I think HGA should be redirected to Directional antenna; LGA could be redirected to Directional antenna or Omnidirectional antenna, I don't care. I think a note should be added to the target articles that the terms HGA and LGA are used for spacecraft antennas but don't have a precise definition when applied to antennas generally. --Chetvorno^TALK 18:58, 14 April 2013 (UTC)

Overuse of images?

The article presently contains 36 images, not counting diagrams. A majority are stuffed into two separate ad-hoc galleries at the top and bottom of the article. While some of the images enhance understanding of the subject, the vast majority are merely shoehorned into the article. Per WP:Galleries and WP:NOTGALLERY, Wikipedia Commons is a more appropriate repository. - LuckyLouie (talk) 14:51, 6 May 2013 (UTC)

I agree that the images are haphazardly selected and not the best, and are poorly organized (I added one of the galleries and I freely admit that my selection of images sucks; I was in a hurry). However antennas are a very visual topic; they are located in plain sight and can be distinguished by their form, and their form usually reveals how they function. So a good antenna article has to have a lot of pictures. Currently the article is very wordy and bloated, as well as disorganized. I'd suggest trimming down the verbiage to make room for more pictures and diagrams. One way to organize the pictures is to have a "beastiary" at the end of the article, with subsections or a bulleted list breaking down the major types of antenna, with each type having a brief descriptive paragraph and a mini-gallery showing a range of examples. --Chetvorno^TALK 16:50, 6 May 2013 (UTC)

Understood. Personally, I enjoy looking at antenna images, but having practically every antenna photo in Commons placed here may not make sense, especially when we already have individual antenna articles that can hold a number of images specific to the type of antenna being talked about (for example Dipole antenna). By the way, this is not a priority issue, I just thought I'd solicit other editors opinions and see what people think. Cheers, - LuckyLouie (talk) 18:54, 6 May 2013 (UTC)

There's a lot of duplication. No need for multiple dish, yagi, LPDA, and rabbits. Glrx (talk) 00:52, 7 May 2013 (UTC)

Antenna vs. aerial?

Is there any difference, either technical or (obviously) etymological, between the two terms?

Are they exactly equivalent? Or are there cases (parabolae?) where one might refer to part of an overall system and the other to the entire device, including reflectors etc.?

Is there a historical and geographical slant to their distinct use?

Andy Dingley (talk) 10:41, 7 June 2013 (UTC)

My sense is that American English uses antenna and rarely uses aerial. American English may also have a distinction that an aerial is made from wires. An wikt:aerialist performs on high wires. Looking at wikt:aerial noun confirms those distinctions are made. Glrx (talk) 00:54, 9 June 2013 (UTC)

In my experience (in America), the terms are more or less interchangeable, but aerial is less common, or perhaps antiquated. However, books show that they appear to have had distinct meanings originally. Read about it. Dicklyon (talk) 02:09, 9 June 2013 (UTC)

Is this confusing?

The intro states- In each and every case, the transmitters and receivers involved require antennas. The list immediately preceding includes Radio Astronomy as a use of antennas. The transmitter antenna may be hard to define in that case. — Preceding unsigned comment added by 76.218.101.72 (talk) 04:04, 17 June 2013 (UTC)

It didn't say that each use required both a transmitting and receiving antenna. There are a variety of research fields like radio astronomy and meteorology that use receivers and receiving antennas to pick up natural radio signals that are produced by the environment. By the way, radio astronomy does use transmitting antennas on occasion. A number of the largest radio telescopes have been used to do radar surveys of nearby planets like Venus, in which the dish sends out a powerful microwave signal which bounces off the planet and is received by the dish again. The microwaves can penetrate the dense cloud cover of Venus as light cannot, to produce a map of the surface. --Chetvorno^TALK 09:51, 17 June 2013 (UTC)

Assessment comment

The comment(s) below were originally left at Talk:Antenna (radio)/Comments, and are posted here for posterity. Following several discussions in past years, these subpages are now deprecated. The comments may be irrelevant or outdated; if so, please feel free to remove this section.

== Too rambling ==

This article is a "Start". It has too much good info. It is a rambling collection of many experts and has too much depth in too few areas and missing the essence of any of them. It is too much math for a encyclopedia article, that should be in text books. I think we should pick a list of subtopics and present each of them with some assessability for laymen. I have proposed a list on the talk page. We have covered too many things and too few of them well. John 04:14, 20 December 2006 (UTC)

BTW, I couldn't figure out how to 'rate' it.

Last edited at 04:31, 20 December 2006 (UTC). Substituted at 14:15, 1 May 2016 (UTC)

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 207.255.205.112 (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. --Chetvorno^TALK 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. --Chetvorno^TALK 17:46, 22 November 2013 (UTC)

ground multipath

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? --Chetvorno^TALK 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.[8][9] 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)

I agree Ground plane would be a good place for it. How do you feel about that as a destination, Mark viking and Interferometrist? --Chetvorno^TALK 06:26, 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)

Disorganized sections

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. --Chetvorno^TALK 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. --Chetvorno^TALK 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? --Chetvorno^TALK 21:02, 22 June 2015 (UTC)

Here's a replacement for the "Basic antenna models" section I have been working on: User:Chetvorno/work8#Antenna types --Chetvorno^TALK 06:46, 23 June 2015 (UTC)

I think "eyesore" is still pretty correct even with my small attempt at WP:PERTINENCE. The proposed replacement looks great! Fountains of Bryn Mawr (talk) 11:47, 23 June 2015 (UTC)

Thank you for the encouragement. Replaced the section. --Chetvorno^TALK 23:22, 29 June 2015 (UTC)

question -- commercial mast arrays

I've noticed in my area (around lake ontario) there are several broadcasting sites which consist of several mast antennas. Looks to be 2 x 4 in a rectangle. What is the purpose of this arrangement? Also, some of the sites seem close to the lake - I assumed you would rather be higher(?) - or does the lake give a nice clear broadcast path (no buildings, trees etc)? Grimsby 43°12'50.6"N 79°36'29.4"W Mississauga 43°30'19.5"N 79°37'53.2"W

Very likely AM broadcast arrays, the 8 towers, are phased to produce nulls in the direction of other stations on the same frequency to prevent interference and to increase signal in desried directions. The towers seem to have nothing on them meaning each tower itself is a vertical monopole antenna working against a ground screen. — Preceding unsigned comment added by JNRSTANLEY (talk • contribs) 00:06, 18 September 2016 (UTC)

External links modified

Hello fellow Wikipedians,

I have just modified 3 external links on Antenna (radio). Please take a moment to review my edit. If you have any questions, or need the bot to ignore the links, or the page altogether, please visit this simple FaQ for additional information. I made the following changes:

When you have finished reviewing my changes, please set the checked parameter below to true or failed to let others know (documentation at {{Sourcecheck}}).

This message was posted before February 2018. After February 2018, "External links modified" talk page sections are no longer generated or monitored by InternetArchiveBot. No special action is required regarding these talk page notices, other than regular verification using the archive tool instructions below. Editors have permission to delete these "External links modified" talk page sections if they want to de-clutter talk pages, but see the RfC before doing mass systematic removals. This message is updated dynamically through the template {{source check}} (last update: 18 January 2022).

If you have discovered URLs which were erroneously considered dead by the bot, you can report them with this tool.
If you found an error with any archives or the URLs themselves, you can fix them with this tool.

Cheers.—InternetArchiveBot (Report bug) 06:27, 15 October 2016 (UTC)

External links modified

Hello fellow Wikipedians,

I have just modified 2 external links on Antenna (radio). Please take a moment to review my edit. If you have any questions, or need the bot to ignore the links, or the page altogether, please visit this simple FaQ for additional information. I made the following changes:

When you have finished reviewing my changes, you may follow the instructions on the template below to fix any issues with the URLs.

This message was posted before February 2018. After February 2018, "External links modified" talk page sections are no longer generated or monitored by InternetArchiveBot. No special action is required regarding these talk page notices, other than regular verification using the archive tool instructions below. Editors have permission to delete these "External links modified" talk page sections if they want to de-clutter talk pages, but see the RfC before doing mass systematic removals. This message is updated dynamically through the template {{source check}} (last update: 18 January 2022).

If you have discovered URLs which were erroneously considered dead by the bot, you can report them with this tool.
If you found an error with any archives or the URLs themselves, you can fix them with this tool.

Cheers.—InternetArchiveBot (Report bug) 01:40, 7 July 2017 (UTC)

POV links

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!). (User: 2003‎ 203.96.111.237) 00:43, 29 July 2003 (UTC)

Voltage and Current of dipole in quadrature?

What's with the animated gif showing voltage and current out of phase?

 https://en.wikipedia.org/wiki/Antenna_%28radio%29#Resonant_antennas

crcwiki (talk) 17:48, 5 September 2017 (UTC)

In what sense? It's just the normal behaviour of V/I for any sort of transmission line - they're out of phase. Consider the basic derivation from

Q=CV

and

I=dQ/dt

, thus:

I(t)=C{\frac {\mathrm {d} V(t)}{\mathrm {d} t}}

When it's a sine wave, then the derivative can be seen as either a cosine, or else the same sine, with a phase shift. Andy Dingley (talk) 18:22, 5 September 2017 (UTC)

Assuming a proper resistive load at the end, the normal phase difference of V/I in a transmission line is near zero. Where did you read otherwise? As for the antenna, if the amplitudes shown represent the voltage (wrt midpoint I presume) and current along the wire of a resonant dipole, the implication is the feed point is reactive which isn't the case. OTOH if we are being shown field strengths or electric charge, that changes things. The animation is likely a bit too simplistic for encyclopedic use and is likely misleading. It has become wildly popular on the internet because it is a cool graphic, but conveying incorrect information. crcwiki (talk) 21:13, 5 September 2017 (UTC)

Bloviation

It sure seems the Wikipedia edicts contained in here...

https://en.wikipedia.org/wiki/Wikipedia:Article_size

...have been utterly ignored for this important article in part due to the copy and paste of other articles within this one. Has anyone even bothered to make this article encyclopedic and not a college text? crcwiki (talk) 14:30, 6 September 2017 (UTC)

This is not a useful observation. Every Wikipedia article contains at least one extra word and one error. Therefore the ultimate Wikipedia article is one word that is spelled wrong. This is the encyclopedia anyone can edit, have at it! -Wtshymanski (talk) 16:46, 6 September 2017 (UTC)

@Crcwiki: I absolutely agree with you; this article is bloated with unnecessary verbiage. The "readable prose size" is 71k which is in the "probably should be divided" range; however I don't think it needs to be split, just edited to remove hot air. Most of the sections on antenna properties are full of unnecessary digressions and chatty examples that sound like they were lifted from QST. They could be rewritten to half their word count and the understandability improved. If nobody else does, I might take a whack at it when I get some time. I'd hate to see somebody try to read this article on his mobile phone. --Chetvorno^TALK 00:16, 18 January 2019 (UTC)

Plagiarism in “characteristics” section

As far as I can tell, almost the entire “Characteristics” section of this page, starting with the “Gain” subsection, has been directly plagiarized from the book Broadcasting Journalism by Jacoby Barrera. (here is a link to the book: https://books.google.com/books/about/Broadcasting_Journalism.html?id=XePEDwAAQBAJ). Specifically, from pages 116-122. I don’t have enough knowledge of this topic to rewrite this, and I am new to Wikipedia and am unsure of the proper proceedings.

PaleBlueSkies (talk) 17:00, 16 June 2021 (UTC)

PaleBlueSkies: Thanks for catching that! You did the right thing. Actually I think in this case the plagiarism went the other way; Broadcasting Journalism copied our article. That section of our article was written before 2019, when the book was published. In fact a lot more of this article appears verbatim in the book. A lot of authors now cut and paste Wikipedia content into their books, since it is in the public domain.

My opinion is the author got the raw end of the deal, as those sections of the article are really badly written. --Chetvorno^TALK 22:11, 16 June 2021 (UTC)

Fractal Antenna needs to be added somewhere.

There is a Wikipedia page on "Fractal Antenna" and I'm confused about it not being mentioned in the Wikipedia page "Antenna." ^[1] Mbman8 (talk) 22:07, 14 June 2019 (UTC)

There are actually a lot of widely used antennas which are not mentioned in the article: the helical, rhombic, T, J-pole, umbrella antenna, mast radiator. Others like the phased array are misdefined, others like the lens antenna are described without mentioning their name, and most others are mentioned in passing without describing what they are.

There used to be a gallery in the article showing examples of the main types of antenna, organized into families: monopole, dipole, loop, aperture, array, traveling wave etc. with a brief description of what each one was. This has been moved to Antenna types. I think this should be restored to the article; general readers need it. There would be plenty of room if we edited down the huge walls of text. This overview article should be rewritten WP:SUMMARYSTYLE with brief summaries of topics with links to explanatory articles. --Chetvorno^TALK 02:14, 17 June 2021 (UTC)

References

^ https://en.wikipedia.org/wiki/Fractal_antenna

Utterly false statement about line parameters

The following sentence is utterly false:

Also, unlike a transmission line which can be modeled using the line parameters

L'

and

C'

(and

R'

and

G'

), no set of such parameters can model a single conductor line.

The statement is complete and utter bullshit (see technical description): The person who wrote it, in fact did not know what he/she was talking about, and made up a statement without any validity, and with no citations.

The text has been ineptly scavenged out of and then removed from Telegrapher's equations article. The cited authors carried in from that text are Raines (2007)^[1] and Schelkunoff & Friis (1952, 1966).^[2] Both books are virtually entirely devoted to modelling antennas as single-conductor transmission lines, which as Raines points out, is at present a lost art. Both books give extensive formulas that are incrementally complicated, that provide exactly the line parameters $L'$ , $C'$ , $R'$ , and $G'$ , or secondary parameters the surge impedance $Z₀$ (usually complex in antennas) and wave number $β$ .

Furthermore, single conductor transmission lines are easily modeled by transmission line equations, both for American-style telegraph lines (single conductor, ground return), and for single-conductor power distribution. (In effect, the ground return is modeled as a resistor.)
107.116.93.6 (talk) 10:09, 21 December 2021 (UTC)

Excuse me, but if I didn't know what I'm talking about then I should give you the name of the university I went to and you tell them to rescind my degree. No, the content was not "scavenged out of and then removed from Telegrapher's equations". No one knows what you're talking about. If you want to dispute such a statement then you need to clearly state the opposite AND supply supporting citations.Interferometrist (talk) 21:12, 5 January 2022 (UTC)

Also, if you are trying to revive a "lost art" then you might question why it was "lost." No, I didn't look those two books up (but if you'd like to send us relevant excerpts, then please post them here!). But I do know that theory involving single-conductor transmission lines with respect to a GROUND couldn't possibly apply to an isolated antenna in space far from any ground, which is the starting point in the analysis of dipole (etc.) antennas, the presence of a nearby ground being an additional complicating factor which may or may not significantly interact with the original solution of currents and E field surrounding an antenna element. Please treat the former editors of this page with more respect and help US understand something new, if that's what you think you have to offer. Interferometrist (talk) 21:29, 5 January 2022 (UTC)

What you say you "know" is mistaken. Thanks for the suggestion of retracting your degree: It's a delicious idea to fantasize about, but either your degree or mine are not going to be expunged over this – the threatened revocation won't happen on either side, although given your vexing remarks, it is tempting fantasy.

Yes, a single-conductor transmission line can work in free space, with no immediate interaction with "earth". Think about the long antenna wires formerly trailed behind airplanes, or originally dangled from Zeppelins (hence the "Zepp" antenna type), or antennas mounted on spacecraft. In all such antennas suspended far from an earth ground, the frame / metal sheeting of aircraft becomes the electrical ground surface that the wire's E-field returns to. In the case of high-gain spacecraft antennas the metal surface of the reflector dish is effectively all the nominal ground, with little E-field returning to the more distant body. More to the point of transmission-line theory for antennas, for long-wire antennas dangling off spacecraft (low-gain emergency antenna) the body of the spacecraft is used as the ground, but usually augmented by an opposing pole (dipole antenna, rather than ground-plane-based monopole), although extended "wing" solar panels might conceivably be used as a counterpoise.

And yes, I'm sorry, but I don't owe you or any other editor a remediation of your education: I retired from teaching about 8 years ago. The text of Schelkunoff & Friis^[2] is available for free from the Internet Archive (archive.org). And honestly: be practical. How could any editor possibly put in an explanation sufficient to every edit? That's why unsourced claims are liable to deletion without notice. Just the fact that the section references two, whole books dedicated to the use of using the telegrapher's equation for modelling antennas (one of them from 1952^[2] and the other from the 2007^[1]) should be a big enough indication to you that it's up to you to become better informed.
166.205.91.47 (talk) 08:08, 2 June 2022 (UTC)

^ ^a ^b Raines, Jeremy Keith (2007). Folded Unipole Antennas: Theory and applications. Electronic Engineering (1st ed.). McGraw Hill. ISBN 978-0-07-147485-6.ISBN 0-07-147485-4
^ ^a ^b ^c Schelkunoff, Sergei A.; Friis, Harald T. (July 1966) [1952]. Antennas: Theory and practice. John Wiley & Sons. LCCN 52-5083. Retrieved 3 June 2022 – via Internet Archive.{{cite book}}: CS1 maint: url-status (link) Link is for the 1952 edition.

[1] ttps://en.wikipedia.org/wiki/Fractal_antenna

[Raines2007-2] Raines, Jeremy Keith (2007). Folded Unipole Antennas: Theory and applications. Electronic Engineering (1st ed.). McGraw Hill. ISBN 978-0-07-147485-6.ISBN 0-07-147485-4

[SchelkFriis1952-3] Schelkunoff, Sergei A.; Friis, Harald T. (July 1966) [1952]. Antennas: Theory and practice. John Wiley & Sons. LCCN 52-5083. Retrieved 3 June 2022 – via Internet Archive.{{cite book}}: CS1 maint: url-status (link) Link is for the 1952 edition.

[1]

[1]

[2]

v t e Antenna types
Isotropic	Isotropic radiator
Omnidirectional	Batwing antenna Biconical antenna Cage aerial Coaxial antenna Crossed field antenna Dielectric resonator antenna Dipole antenna Discone antenna Folded unipole antenna Franklin antenna Ground-plane antenna G5RV antenna Halo antenna Helical antenna Inverted-F antenna Inverted vee antenna J-pole antenna Mast radiator Monopole antenna Random wire antenna Rubber ducky antenna Sloper antenna Turnstile antenna T2FD antenna T-antenna Umbrella antenna Whip antenna
Directional	Adcock antenna AS-2259 Antenna AWX antenna Beverage antenna Cantenna Cassegrain antenna Choke ring antenna Collinear antenna array Conformal antenna Corner reflector antenna Curtain array Folded inverted conformal antenna Fractal antenna Gizmotchy Helical antenna Horn antenna Log-periodic antenna Loop antenna Microstrip antenna Moxon antenna Offset dish antenna Patch antenna Phased array Planar array Parabolic antenna Plasma antenna Quad antenna Reflective array antenna Regenerative loop antenna Rhombic antenna Sector antenna Short backfire antenna Slot antenna Sterba antenna Vivaldi antenna WokFi Yagi–Uda antenna
Application-specific	ALLISS Corner reflector (passive) Evolved antenna Ground dipole Reconfigurable antenna Rectenna Reference antenna Spiral antenna Circularly disposed antenna array Television antenna

Staggering Length of this Article

External link question

Nature of the EMF

Electrically Short Antenna

Stuff to add to this article

Plural of Antenna

transmitting vs. receiving antennas

Antenna Theory Section

Canadian Flag

Impedance? Electrically short?

Gain and how does it work

patents

Gain, what is it?

Contradiction, what's correct??

Antenna / Ariel

Antenna / Ariel

Loop antenna

Overview section

Ordering of Ideas

Introduction

slow revisions, other ways to reduce size

Origin of word "antenna"

Polarization secton

Marconi and term "Antenna"

What is and isn't an antenna

Headings name the article title

angle of incidence

Some clean-up

Physical background

A Query..

Reordering the article

120 π {\displaystyle 120\pi } or Z 0 {\displaystyle Z_{0}} ?

Unfairly

Human body as antenna

Computer external antennas for wireless connection

Merging Antenna measurement with this Article

Too many antenna models

Navbox

Fractal Antennas

any LC circuit

Antenna element length

Wiring

Aerial made of multiple "rabbit ears"

Resonance?

Television antenna

Image gallery

Log periodic antennas not mentioned!

Recent (and further) changes

needs disambiguation and expansion

Inaccurate definition

Short antennas are poor performers

Invalid reference to "velocity factor"

section on resonant antennas misleading/got errors

Removal of "Maximum power transfer requires matching the impedance"

Remove "An antenna with a low gain emits radiation with about the same power in all directions"

Opposite side lobe

Current produces magnetic field wave, charge produces electric field wave?

Antennas / Antennae

Do omnidirectional antennas have gain?

Merger or Simplification Proposal

Reciprocity Section

Removal of "Reactance diverts energy into the reactive field"

"fairly thin conductor"

Merge High gain antenna, Low gain antenna, and/or Directional antenna?

Overuse of images?

Antenna vs. aerial?

Is this confusing?

Assessment comment

Antenna converts electron movement into photons

ground multipath

Disorganized sections

question -- commercial mast arrays

External links modified

External links modified

POV links

Voltage and Current of dipole in quadrature?

Bloviation

Plagiarism in “characteristics” section

Fractal Antenna needs to be added somewhere.

Utterly false statement about line parameters

$120\pi$ or $Z_{0}$ ?