Talk:Radio frequency

From Wikipedia, the free encyclopedia
Jump to: navigation, search
          This article is of interest to the following WikiProjects:
WikiProject Electronics (Rated Start-class)
WikiProject icon This article is part of WikiProject Electronics, an attempt to provide a standard approach to writing articles about electronics on Wikipedia. If you would like to participate, you can choose to edit the article attached to this page, or visit the project page, where you can join the project and see a list of open tasks. Leave messages at the project talk page
Start-Class article Start  This article has been rated as Start-Class on the project's quality scale.
 ???  This article has not yet received a rating on the project's importance scale.
WikiProject Physics (Rated Start-class, High-importance)
WikiProject icon This article is within the scope of WikiProject Physics, a collaborative effort to improve the coverage of Physics on Wikipedia. If you would like to participate, please visit the project page, where you can join the discussion and see a list of open tasks.
Start-Class article Start  This article has been rated as Start-Class on the project's quality scale.
 High  This article has been rated as High-importance on the project's importance scale.
WikiProject Radio (Rated Start-class, Top-importance)
WikiProject icon This article is within the scope of WikiProject Radio, a collaborative effort to improve the coverage of Radio-related subjects on Wikipedia. If you would like to participate, please visit the project page, where you can join the discussion and see a list of open tasks.
Start-Class article Start  This article has been rated as Start-Class on the project's quality scale.
 Top  This article has been rated as Top-importance on the project's importance scale.
Wikipedia CD Selection
WikiProject icon Radio frequency is included in the Wikipedia CD Selection, see Radio frequency at Schools Wikipedia. Please maintain high quality standards; if you are an established editor your last version in the article history may be used so please don't leave the article with unresolved issues, and make an extra effort to include free images, because non-free images cannot be used on the DVDs.
Today's articles for improvement
WikiProject icon This article was selected as Today's article for improvement on 20 May 2013 for a period of one week. WikiProject icon


Isn't there a ELF, Extreme Low Frequency ?

Yes, but there doesn't seem to be agreement on the extent of it, so I finally settled for "below 3 kHz." -Palmpilot900

Try Extremely low frequency (SEWilco 08:34, 27 May 2005 (UTC))

This page is lacking in many areas IMHO.[edit]

First off BNC is (British Nut Connector or it varies) (and this is most often Video, or in it rg58 form yes RF) The most common connector is a F connector on a RG6 cable vis-a-vis house hold cable or outdoor antenna connection. Not a BNC.

Also need to mention RF radiation. (IE are you getting zapped) RF Engineering.

And the H and vertical elements and magnetic.

(above from anonymous)

I would have to agree with the fellow above, this articule is lacking in many areas. Unlike some people on this discussion board, I feel merging the Radio Frequency page with the Radio Wave page would add confusion to the reader. On the other hand I'd suggest linking the Radio Wave page to the Wave page, because of the Wave Propagation section. After all there are many kind of Waves: Radio, Light, Sound, Energy, Shockwaves, Kinetic, etc. Wave Propagation applies to most/all of them does it not?

Also, some mention or links to the different radio spectrum regulatory commissions (ie: FCC, EU, IEEE, etc) wiki pages would be helpful aswell.

More charts[edit]

Maybe would be of use. (SEWilco 08:34, 27 May 2005 (UTC))

RF Connectors[edit]

Entering RF in search goes to RF disambig page, not here, so the RF connectors should be moved there. They really don't belong on this page. --Blainster 16:27, 14 July 2005 (UTC)

Is there a radio spectrum pollution article anywhere?[edit]

Hello. Can anyone with an interest in this article suggest an article somewhere that might discuss radio spectrum pollution? (More specifically, the problem of radio frequencies overlapping and so on -- I don't know if there are other names for it.) I'm not exactly an expert on the electromagnetic spectrum, but a while ago I thought that the Light pollution article should be disambiguated from non-visual light, because as related as they are on some levels, that article doesn't presently discuss anything other than visible spectrum light pollution. (It's also quite long, and the topics might work better being split anyway.) At the time, I made a stub article called Radio spectrum pollution, but it's been a stub for a while, and I'm wondering if there might be a better place to disambiguate to. Thanks for any help or suggestions. Izogi 04:05, 3 April 2006 (UTC)

Howard6 06:17, 22 March 2007 (UTC) The page exists. There are issues within RF which correspond to light pollution; the main difference is that the main concern in the RF area is the effect the extraneous RF has. The correct term when considering unwanted radio waves would be "Radio Frequency Interference". See interference.


I propose merging this article with radio waves, and suggest that wave radio would be the best title for the combined article. Discussion is at talk:radio waves#Merge.--Srleffler 01:20, 3 February 2007 (UTC)

support merge with preferred surviving name of Radio frequency Anlace 18:51, 4 February 2007 (UTC)
I ve read the old posts, but they are not very convincing on the name. It sounds like there is agreement on the merger. The name really should be Radio frequency. Doesn't anybody else here work in this field? Besides being outmoded, the term "radio wave" is really not nearly as encyclopaedic as "radio frequency". Google hits are 20:1 supporting Radio frequency, but more importantly Radio frequency hits are clearly tied to the more encylopaedic literature whereas many of the "radio wave" hits are linked to pop-science etc. Anlace 23:00, 7 February 2007 (UTC)

Electrumz 05:07, 19 February 2007 (UTC) 05:02, 19 February 2007 (UTC) I was searching for information regarding RF inductance coils from the inductuction coils page and was lead to this page about radio waves. Perhaps there is not a page for what I was looking for; however, if there was, has it been replaced by this page? Electrumz 05:07, 19 February 2007 (UTC)05:02, 19 February 2007 (UTC)

Howard6 06:14, 22 March 2007 (UTC) against merge I am an electrical engineer with 30 years experience in RF design and working with radio waves; the two terms have very different connotations even though they sound similar. Amongst the engineering and telecommunications community, "Radio Frequency, or RF" defines a distict field of engineering and in this respect is a bit of a misnomer. "Radio Waves" are only one phenomenon within the broader field of RF. "Radio Waves" refers to the existence of waves in air and space; "RF" also refers to the circuitry which controls and modifies these waves and the existence of these waves within RF circuitry.

But this article is not about RF circuits; that's at radio electronics. -- Beland 15:53, 22 June 2007 (UTC)
Interesting comment, maybe radio electronics needs to be merged with electronics. This article is about RF itself (mainly RF electrical currents), not RF circuits, and not waves. It seems to me RF is distinct enough from those topics to warrant an article, if it is not distinct, we can delete it, but not combine it with something technically unrelated but often confused with. If it appears RF should be merged with Radio Waves, perhaps the articles don’t describe them properly.
Surprisingly (to me) there must be a lot of confusion about the distinction between waves and frequency. To combine the articles would simply add to the confusion so Im against merge. Before we can proceed with a discussion, it might be a good thing for participants to first understand the distinction.
Radio frequency is a kind of frequency. Radio frequency could conceivably be discussed under the topic frequency, but it would make the RF article unaccessible under that topic. It would not make common sense.
Radio waves is not a kind of frequency because waves are not frequency. Frequency is the time rate of oscillation, it does not travel. RF does not travel through space, RF is not even a thing, it is a rate of change of something, usually current. This is the way we most often use it (technically that is also a slight misuse, but conventional) is for electric currents, but never (properly) as a wave.
Waves are a thing, they travel through space. Just because waves can have a property of frequency doesn’t make them the same thing nor does it imply that any kind of waves are a subset of any kind of frequency, or vice versa. Waves have a property of amplitude too, but why are there no suggestions to combine it with some kind of amplitude topic? (I may regret that question...)John 06:00, 2 October 2007 (UTC)


what does the "M" in front of the hertz mean?

Mega, as in Megahertz. -- Beland 15:52, 22 June 2007 (UTC)


The wave lenghts are wrong. They are much too big. Check out the formula here in wikipedia under wavelenght.

They agree with the chart on Electromagnetic spectrum. -- Beland 16:03, 22 June 2007 (UTC)

article name[edit]

I came to this article for a definition of "radio frequency". Alas, there doesn't seem to be one. Instead, the article is about radio bands, and electromagnetic waves.

In normal usage, does a 500 kHz signal qualify as RF? What about 50 kHz? —EncMstr 22:34, 22 June 2007 (UTC)

Yes and yes. John 06:02, 2 October 2007 (UTC)

Rework of this article[edit]

This article used to contain a great deal more information. It was all deleted as a minor edit about six months ago [1]. This is really inappropriate to delete 90% of an article and not discuss it on the talk page AND mark it as minor. I was about to restore it before I realised that most of the deleted information is now in radio waves. Still not sure I shouldn't have just restored it. The editor who did this seems to think that this article should be about radio frequency other than transmissions. I find this a bit odd. I expect to find here information on radio bands - I followed a link that said it was here. The radio waves article I would expect to be on the physics of radio propagation. The table of bands has since been recreated by other editors but there were other tables and several templates were using them. I have fixed the MWband template but there are others. There are also a huge number of incoming links from all over the wiki many of which are expecting information that is not here any more. In short the job was botched and was not by consensus in any case. I propose to reverse the change. SpinningSpark 20:36, 2 May 2008 (UTC)

I made the mistake of unintentionally classifying this as "minor" and attempted to correct that, but failed. But it was discussed as de-conflicting this with radio waves. I hope I didn't remove something that should not have been removed, if you think so, please point it out. The material you point out did not address RF, it addressed radio waves. I know that the term RF sometimes is used to loosely refer to radio waves, but the reference overloads terms when we look closer. John (talk) 20:02, 9 July 2008 (UTC)
Can you point to where this discussion took place. I see you arguing against a merge in the discussion above. I don't see any agreement to take vast swathes of the article somewhere else. I have been intending to reverse this change for some time but have not done so because to do it properly is complex and I have not had time. The argument that the breakdown of frequency bands should not be here is entirely obscure to me, this is the natural place people will come looking for that information through the common useage of the term. It is Wikipedia policy that names of articles should be the commonly used names. To quote you part of that policy;
The names of Wikipedia articles should be optimized for readers over editors, and for a general audience over specialists.
I came to this article looking for K band microwaves. It should be here because it is expected to be here, it is not. It's that simple. Arguing from the dictionary semantics of the words really does not wash, it is how the terms are used in reality that counts. That I am right that this is the normal terminology is borne out by the fact that a succession of other editors have recreated the main table without ever finding the place where you moved the original one to. In any case (referring to some of your comments in the post below) from a theoretical point of view any electrical (or magnetic for that matter) oscillation must, by the fundamental laws (Maxwell's) of e-m propagation, produce electromagnetic waves. This cannot be avoided. The waves can be contained so that very little escapes to the outside world, but it is not possible to avoid producing them, even in principle. Sorry I did not respond sooner, I watch this page but I managed to miss your post. SpinningSpark 11:22, 9 November 2008 (UTC)
I do not recall where the discussion is, it has been a while. The idea of the discussion was whether or not to merge radio waves and RF as they are not the same thing. Your point that RF produces radio waves is true, but aren't they still distinct? I don't think misuse of the term justifies merging the two. It does not seem esoteric at all to distinguish RF from EM waves, I don't think most RF engineers use the terms interchangeably. I think your point about reader priority argues to encourage laymen to do so, but it would not seem correct enough for an encyclopedia. When you look for microwaves, I would think you would view those as EM waves more than as a frequency. The problem is that the breakdown of frequency bands by wavelength only works for EM waves, unless the topic is propagation in free space, wavelength seems to be a little off topic.
What do you think of having something in RF pointing to those EM wavelength tables? Could an approach like that work for you? John (talk) 03:09, 10 November 2008 (UTC)
If you are suggesting a seperate article with a link from here, then yes, I could live with that, but it would have to be a new article radio band chart or some such. I think radio wave is completely the wrong place, which I would expect to be a physics article. My main complaint remains that the backlinks from various articles to here were not dealt with when the article was changed. Although I fixed the link template:MWband, which was the one I was interested in, I am sure there are many others and it is a non-trivial amount of work to go through them (both here and at Radio wave) and really the responsibility of the person who split up the article in the first place. SpinningSpark 20:35, 13 November 2008 (UTC)

Frequency Range[edit]

I know some radio systems operate at very low frequencies, but does "Radio frequency" generally refer to something as low as 3Hz? Could we find a way to indicate a "normal" RF range (i.e. somewhere above the audio frequency range)? I've just linked here from the MRI page, but this page really doesn't indicate quite what I was hoping for. GyroMagician (talk) 07:39, 3 July 2008 (UTC)

I don't know if there is an answer to that in general but I would be surprised to hear about use of 3Hz RF. Beacons routinely produce RF below 100 KHz. Pre 1920 spark radios sometimes used frequencies below 20 KHz. Usually, antennas are used to produce RF, and the size of a practical antenna drives the lower useful limit. But then you can make a radio wave of any frequency by waving a magnet (or a charged stick) slowly, but sensing it is a challenge. So any lower bound is an artificial bound. John (talk) 20:17, 9 July 2008 (UTC)
From an electronic engineering perspective, if I know a signal is RF it tells me something about how I have to handle it (line impedance, proper termination, radiation, etc) - things I don't have to worry about at lower frequencies. So yes, in principle a radio wave can be generated at any frequency, but I think to most engineers "versed in the art" RF means something specific about the frequency range. In my area-of-interest (MRI) references to RF do not (or should not) even involve radio waves - it's about a time-varying non-radiating magnetic field. It's called an RF field because it oscillates in the MHz range. I think this kind of usage is fairly common. I'm not sure how to describe this usage for this page though? GyroMagician (talk) 07:21, 14 July 2008 (UTC)
GyroMagician, from an electronic engineering perspective, I do not think the term RF implies radiation is involved, that overloads the term. While RF can produce EM waves, the overwhelming majority of occurrences of RF in todays electronics involve no EM waves, such as the one you cite. Why wouldn't the conventional term "VHF," or "very high frequency" describe that usage precisely? John (talk) 01:46, 9 November 2008 (UTC)
What I am trying to say is that I expect different design problems for an RF circuit than, say, an audio-frequency circuit. I would like to find a way to express that in this article. The 'special properties' section goes some way toward this. I do not think most engineers or scientists would normally consider 3Hz (why 3?) to be radio frequency, although it is perfectly possible to produce a radio wave at such a low frequency. For the casual reader I think such a wide definition is confusing. GyroMagician (talk) 12:00, 10 November 2008 (UTC)
That is a good point, do you have ideas on how to deal with that. The problem I see is that various factors affect design as frequency changes, not just "RF" v. DC. Maybe someone could list those factors and the frequency where they are considerations. Or just mention that factors exist? John (talk) 17:17, 10 November 2008 (UTC)
I totally agree with GyroMagician, I was astonished looking at this wikipedia page. I, as an electronic engineer, use the term RF (Radio Frequency) as a subset of the electromagnetic spectrum. Here it is a small table I produced over the last years:
Band name Common abbreviation Frequencies Wavelenghts
Audio frequencies (AUDIO) below 30 kHz over 10 km
Radio frequencies RF 30 kHz – 1 GHz 30 cm – 10 km
Microwave frequencies μW 1 GHz – 300 GHz 1 mm – 30 cm
Infrared frequencies IR 300 GHz – 150 THz 2 μm – 1 mm
Near-infrared frequencies NIR 150 THz – 385 THz 780 nm – 2 μm
Visibile frequencies (VIS) 385 THz – 790 THz 380 nm – 780 nm
Ultra-violet frequencies UV 790 THz – 500 PHz 600 pm – 380 nm
X-rays frequencies X 500 PHz – 30 EHz 10 pm – 600 pm
γ-rays frequencies γ over 30 EHz below 10 pm
If you want, I can try to find the book(s) I used to write this table. I hope you will take this in regard. 18:48, 2 December 2008 (UTC)
Yes, please do! This would be an excellent addition to the article. —EncMstr (talk) 19:28, 2 December 2008 (UTC)

FRS and GMRS[edit]

can someone list where in this chart FRS and GMRS is? i think it can be useful for beginners.

thanks —Preceding unsigned comment added by (talk) 05:09, 22 December 2008 (UTC)

ELF aren't audible[edit]

By convention the audible range is 20Hz to 20kHz which only partially covers ELF. Please correct the table text. —Preceding unsigned comment added by (talk) 18:26, 26 April 2009 (UTC)

Yes check.svg Done You're free to make such changes yourself: This is an open wiki. I've made a change; if you have ideas for improvements, be bold. —EncMstr (talk) 19:10, 26 April 2009 (UTC)
A mention on the page about the range that human hearing falls in would be an improvement. No mention is made about sound or audio at the moment. Jonpatterns (talk) 18:14, 17 April 2014 (UTC)

Merger proposal[edit]

I think Radio spectrum should be merged into this article. RS is a terrible article with no references, but there are nearly 100 links to it, so it needs to be fixed somehow. Thoughts anyone? Jonverve (talk) 21:13, 15 May 2009 (UTC)

  • Merge: I agree. It isn't clear how Radio spectrum might be expanded any further. This article (radio frequency) is reasonably on track for assimilating radio spectrum. Looks like one paragraph or so would add to it nicely. —EncMstr (talk) 21:31, 15 May 2009 (UTC)
  • I don't agree. RF refers purely to the frequency, not necessarily to electromagnetic waves. Since there has apparently been no activity on this for ages, I've done what seems sensible to me, which is move the frequency bands table to Radio spectrum. (talk) 01:51, 4 November 2009 (UTC).
In fact, it might be better to merge Radio spectrum with Radio waves? —Preceding unsigned comment added by (talk) 02:50, 4 November 2009 (UTC)
  • I support merging Radio spectrum and Radio waves, but oppose merging this article (Radio frequency) into either. As points out, just because a signal is oscillating at RF doesn't mean there are any waves emitted. I think this article should be about fast (RF) signals in circuits, and why that is different to lower frequency design. GyroMagician (talk) 11:38, 4 November 2009 (UTC)
"just because a signal is oscillating at RF doesn't mean there are any waves emitted" Exactly how does that occur?? Has some recent discovery proven Maxwell's equations to be wrong?? This has profound implications! Zen-in (talk) 07:01, 7 November 2009 (UTC)
Probably he means just because it's RF doesn't mean that there are significant or relevant waves emitted. That is, the frequencies may mostly affect what's on wires, not wireless or radio, unless there are antennas involved. There are waves on wires, too, of course, but if the wires are very short compared to a wavelength, that's not so relevant to the situation; and it's not radio. Dicklyon (talk) 08:35, 7 November 2009 (UTC)
Yep, that's what I meant. Think of designing an RF amplifier, rather than the antenna. Okay, there will be some small emission, but it's usually undesired and I don't think most designers would consider it. As another example, think of an RF probe for MRI - it's a near-field device, designed not to radiate.GyroMagician (talk) 11:40, 7 November 2009 (UTC)
You cannot have a travelling wave on a wire without emissions. This is an immutable property of radiation. If there is a near field there is far field. The only exceptions to this are Clown Physics, which has been known to exist in Wikipedia. Zen-in (talk) 16:04, 7 November 2009 (UTC)
What's your point? Are thinking someone is taking the clown side in your strawman argument? Dicklyon (talk) 18:52, 7 November 2009 (UTC)
  • Should not Merge – The distinction between radio frequency and radio waves is too great. We need to clean up the article on radio frequency and get it to mean frequency, it has wandered back to radio. John (talk) 02:33, 7 November 2009 (UTC)
  • Oppose merge – the logic of merging is flawed. Radio spectrum's content needs to be fixed, whether it's merged or not. So I added three refs and a bit more sourced info to it. There is a lot of duplication of this spectrum stuff in Radio wave but I'd argue that it should be removed, and that article expanded along the lines of a physics article, focusing on the EM wave nature as opposed to frequencies. Dicklyon (talk) 03:02, 7 November 2009 (UTC)
  • Per Dicklyon, I agree that the spectrum chart should be moved from radio wave which is essentially a physics article. Some history, the chart was originally here but got moved to radio wave; on some totally spurious grounds in my opinion. Various editors then started adding back band information here and effectively reconstructed the chart, probably without realising where the original information had been moved. This second chart was subsequently moved to radio spectrum. The whole thing is a mess and I had intended to do something about it for some time, but it was too complicated to find the motivation. SpinningSpark 12:33, 7 November 2009 (UTC)
  • Assuming Radio spectrum is to be retained, it does, IMO, definitely need to contain the table of bands and their commercial uses. To me, that's what the term "radio spectrum" is essentially talking about. (talk) 20:30, 7 November 2009 (UTC)

Resonant Frequency Formula[edit]

the resonant frequency formula needs fixed, the formula should be 1 over 2pi times the square root of L times C, i tried to fix it but idk how to get 1 to go over the entire formula.-- (talk)

Done. I swapped a \over b to \frac{a}{b} while I was there - it always seems more intuitive to me, but maybe I spend too long coding ;-) GyroMagician (talk) 16:24, 26 April 2010 (UTC)

thanks dude-- (talk) 17:03, 26 April 2010 (UTC)

Silly Situation (Hz vs. kHz)[edit]

We appear to have a one-letter edit war. Or a 'k' flashing at a very low frequency! Rather silly. On the one hand, radio waves can most definitely be produced at 3Hz. On the other hand, I don't think any electronic/electrical engineer would define 3Hz as radio-frequency. What should be done? GyroMagician (talk) 07:34, 31 May 2010 (UTC)

Thanks for adding this; it was something I meant to do after the last revert. I've been removing the k in 3 kHz to be consistent with the article contents. The only idea I have to prevent an endless loop of deleting and re-adding the k is to add a wikicomment explaining that it is not a mistake. Any other ideas? —EncMstr (talk) 08:30, 31 May 2010 (UTC)

LC resonant circuit[edit]

I have reverted an edit by a user which is trying to insert that 1/√LC is only approximate for parallel tuned circuits. Previously reverted by another editor. For a tuned circuit without loss the expression is correct in both cases. The underlying assumption of the edit is that there is a loss due to series resistance of the inductance coil. It could equally be said that tanδ losses in the capacitor dielectric will make the expression inexact for series tuned circuits. Saying one is exact and the other is not is misleading. In any case, I don't think it is helpful to the reader to mention exactness in this particular article - it does not really add anything to the understanding of the subject of the article. At most, a link to an article where the issue is properly explained could be inserted. SpinningSpark 16:52, 8 September 2010 (UTC)

Yes, I agree, that this might not be the correct place to discuss the equations for resonance. But somehow my pedantic side is telling me that you shouldn't publish the wrong equation, so maybe that means don't mention the equation at all! Check your text books guys ... the equation for series resonance does not include R, as follows:

fr = 1/2pi * 1/sqrt(LC}

which is approximately correct for parallel resonance as well, but more accurately given by:

fr = 1/2pi * sqrt(1/LC - R^2/L^2)

In other words, R can shift resonance (albeit slightly, and only in the parallel situation). I rest my case and await your humble apologies! (talk) 13:02, 9 September 2010 (UTC)

Perhaps you could cite *your* textbook that shows this anomalous situation? Resonance is resonance and it doesn't matter if it's series or parallel - resistance in the circuit will disturb it. Is that a parallel resistance or a series resistance, by the way? --Wtshymanski (talk) 13:08, 9 September 2010 (UTC)
Take a look at [2], one of the zillions of books on Google Books (even the ones by Tata McGraw Hill agree on this). Make R big enough and the resonant frequency becomes imaginary? --Wtshymanski (talk) 14:05, 9 September 2010 (UTC)
Please don't ask for apologies, especially when you are in the wrong. The formula is exact for a circuit of ideal L and C for both series and parallel. There are many ways a circuit can become non-ideal and before you can say how this effects the formula you need to say what non-ideal effect you are taking into account. Please think about what you are claiming rather than blindly copying formulae from text books - better still read your text books so you understand why they are saying what they say. A common design problem with tuned circuits is the resistance of the copper winding of the inductor. The simplest model for this is resistance in series with the inductor and this will indeed give the results you state. However that is not an exact model and besides, there are many other non-ideal effects which sometimes have to be modelled. Dielectric losses in the capacitor are often more important at UHF/microwave than the inductor copper and this will have precisely the opposite result to your quoted formulae. The dielectric loss is modelled as a resistor in parallel with the capacitor; this will not affect the parallel resonant frequency, but it will change the series resonant frequency. Other effects which need incorporating are inter-turn capacitance, eddy current losses in the inductor core, hysterysis, distributed elements &C.
If you want pedantic exactness you will need to add all of these (and probably a few I haven't thought of off-hand). However, it won't be helping the article, it is enough to leave it as just a simple LC. If you really believe that equations should not be mentioned in this article at all, then you are defeating your own purpose by trying to expand them. SpinningSpark 15:26, 9 September 2010 (UTC)

OK, I am going to persevere in the face of opposition. I have a library of 100s of books on radio and electronics, most of them are quite old (like me) and you might laugh, but I trust them! I checked Renton's "Telecommunications Principles" and Langford-Smiths "Radiotron Designers Handbook"; they both agree with my views. Also please see and The resistance is usually shown as series to the inductor, where it is likely in fact to be the most dominant circuit imperfection. (talk) 15:34, 9 September 2010 (UTC)

Weird definitions of resonance that lead to imaginary frequencies seem to crop up in physics-oriented books, but in electronics-oriented books I find the usual definition is to the effect "Xl=Xc", and a maximum/minimum of circuit impedance. Define "resonance", I suppose. You can put the resistance anywhere, really...could be shunting the capacitor, etc. --Wtshymanski (talk) 16:58, 9 September 2010 (UTC)
Is this "hyperphysics" place even reliable? They use different definitions of resonance for the series and parallel cases and so come up with different expressions. --Wtshymanski (talk) 17:03, 9 September 2010 (UTC)
Series resonance with a lossy capacitor is explained in this book. The RLC circuit article gives this book as a reference for the same thing but unfortunately Google does not have a preview. You can get a preview at Amazon, but only if you have an account and have made a recent purchase. SpinningSpark 17:55, 9 September 2010 (UTC)
You need page 5-26 and read the sentence "First, note that this is not equal to the commonly quoted expression..." SpinningSpark 18:02, 9 September 2010 (UTC)
My "Radiotron Designer's Handbook" is packed away during the renovations; there may be an on-line .PDF somewhere. --Wtshymanski (talk) 17:59, 9 September 2010 (UTC)
Sribd, as usual, can be relied on to have a pirated copy of everything. SpinningSpark 18:16, 9 September 2010 (UTC)

Radio frequency vs radio waves[edit]

I've just rolled back (most of) several edits. Those edits were largely to do with radio waves not radio frequency, and they are not the same thing. We already have an article on radio waves, and perhaps some of the material can or should be added to that article, if it is not already there. Mitch Ames (talk) 04:28, 10 April 2011 (UTC)

ET phone home[edit]

The Very low frequency article has a table of transmitted signals. 17.5 kHz seems to be transmitting 20 second pulses, but the source is not listed. Is ET trying send a message to Jodie Foster. That article doesn't seem active so I thought I would post here. Is there any info about it to update the table or should I just put Lakeview Cemetery in Ithaca, New York as the source?--Canoe1967 (talk) 19:21, 15 June 2012 (UTC)

I'm surpised both the table in the article and here in the talk have errors[edit]

Hi there,

I was looking that the rf spectrum table and noticed the format of both the frequency column and wave length column do not match

example 3 – 30 MHz does NOT correspond to 10 – 100 m

the author or an editor needs to decide which column should determine the order of magnitude and then match the range in the other column accordingly

example 3 - 30 Mhz, 100 - 10 m (NOT 10 - 100 m)

I'm surprised this boo-boo is both in the article and here in the talk.

I'm going to guess that this is just an oversight because we wouldn't want readers to get confused that small number frequency = small number wave length which is I know that everyone here on this talk page knows is incorrect :-) — Preceding unsigned comment added by (talk) 21:54, 17 June 2013 (UTC)

I agree. Should we leave the Hz ascending and the wavelengths descending?--Canoe1967 (talk) 00:51, 18 June 2013 (UTC)

Don't we need a section on this chart that says "range" for the distance the signals are effective at?[edit]

Frequency Wavelength Designation Abbreviation[1]
3 – 30 Hz 105 – 104 km Extremely low frequency ELF
30 – 300 Hz 104 – 103 km Super low frequency SLF
300 – 3000 Hz 103 – 100 km Ultra low frequency ULF
3 – 30 kHz 100 – 10 km Very low frequency VLF
30 – 300 kHz 10 – 1 km Low frequency LF
300 kHz – 3 MHz 1 km – 100 m Medium frequency MF
3 – 30 MHz 100 – 10 m High frequency HF
30 – 300 MHz 10 – 1 m Very high frequency VHF
300 MHz – 3 GHz 1 m – 10 cm Ultra high frequency UHF
3 – 30 GHz 10 – 1 cm Super high frequency SHF
30 – 300 GHz 1 cm – 1 mm Extremely high frequency EHF
300 GHz - 3000 GHz 1 mm - 0.1 mm Tremendously high frequency THF

--Wyn.junior (talk) 04:16, 2 March 2014 (UTC)

The ranges over which these frequencies can be used for communication depend on too many things, like do you mean between points on the surface of the earth? or in space? Do you mean to include other effects than curvature of the earth and ionospheric bounce? Etc. So there's really no answer that would make sense in the table; unless you find a source that attempts to do something that would be worth mentioning. Dicklyon (talk) 05:57, 2 March 2014 (UTC)
I guess I am talking about maybe setting up a point of communication distance for reference. Or maybe both in space and in an urban setting. I haven't found any sources for this info, though it seems very important to note.--Wyn.junior (talk) 10:44, 2 March 2014 (UTC)
It is important, but probably too complex an issue to sum up in a neat table. Range depends significantly on things other than wavelength, such as transmitter power, type, size, and height of antenna and mode of transmission. Ground waves, tropospheric scatter and skywaves can all achieve greater ranges than line-of-sight propagation. Skywaves are particularly interesting in this question because there is a range greater than line-of-sight but less than the maximum skywave distance that skywaves cannot reach. Thus, giving a maximum number would misleadingly include numbers that cannot be reached. Skywaves can also achieve greater than the maximum range in some circumstances with multiple hops by bouncing off reflective surfaces such as oceans and lakes. Further, the effectiveness of sky waves depends on time of day due to daily changes in the ionosphere. If you are asking what is the maximum range a radio transmission could be made under any circumstances whatsoever then the answer is unhelpfully the size of the observable universe since a transmitter placed in space outside the Earth's atmosphere can transmit to anywhere not obscured by another object. But I don't think that an entry of 14 gigaparsecs against every frequency band would actually be a useful addition to the table for anyone. SpinningSpark 20:50, 2 March 2014 (UTC)

misunderstanding of attenuation, power, and wavelength[edit]

in the paragraph "Thus, under similar conditions of propagation, the higher frequency signal attenuates faster than the lower frequency signal and becomes too weak to be detected at the end of the receiver, located at larger distances. An RF power amplifier is used to amplify the power level of such a transmitter RF Signal, so that it can travel larger distances with less attenuation."

1) the attenuation is independent of power, so higher power creates a higher signal, not less attenuation

2) also, the relation between wavelength and attenuation should be made more explicit (attenuation is per distance, not cycle, so to first order it should also be independent of frequency) Chris2crawford (talk) 16:34, 14 March 2014 (UTC)

Pretty much garbage, and it's uncited. I've removed it. SpinningSpark 22:57, 14 March 2014 (UTC)

Comments on the article[edit]

On the 12th of June I posted some comments that have been removed by EncMstr. Again, here are my comments on this article.

1. "High-power exposure to microwave RF is known to create a range of effects from lower to higher power levels, ranging from unpleasant burning sensation on the skin and microwave auditory effect, to extreme pain at the mid-range, to physical burning and blistering of skin and internals at high power levels (see microwave burn)."

This sentence does not make much sense to me. It's either incomplete or it needs to be rewritten.

2. "Additional rational for EMF restrictions is to avoid auditory effect and energy-induced unconsciousness in rats."

I don't understand this sentence. I think it needs to be rewritten.

3. The 3 links under "General RF exposure" should be moved to the "See also" section.

ICE77 (talk) 04:44, 8 July 2015 (UTC)

  1. ^ Jeffrey S. Beasley; Gary M. Miller (2008). Modern Electronic Communication (9th ed.). pp. 4–5. ISBN 978-0132251136.  Cite uses deprecated parameter |coauthors= (help)