Talk:Standing wave ratio

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Note to ssd: I added a mention that the reflection coefficient is complex. Perhaps there is more we could say about this quantity, but I suggest that extra information goes in to the reflection coefficient article, not this one. Unless, that is, you care to explain how the phase of ρ can affect the SWR. That is beyond my understanding, but you might like to have a go. -- Heron 12:14, 24 Jul 2004 (UTC)

Probably mentioning phase angle is enough, although one of these articles (perhaps not this one) should mention complex conjugate impedance match. Actually,now that I think about it, that would best go in an article on antenna tuner which does not yet exist. As you said before, probably the equations for resistive loss and dielectric loss should go in the transmission line article where it talks about decibels per foot. --ssd 17:01, 24 Jul 2004 (UTC)

The image "Standing wave ratio for ρ = 0.5" is useful, but could someone edit out the microsoft office grammar check green squiggly underlines in the axis labels?

Contents

[edit] radiation burn

Abnormally high voltages in the antenna system increase the chance of accidental radiation burn if someone touches the antenna during transmission.

Here's my understanding:

Could someone who knows these things fix up one of these articles: Standing wave ratio, radiation burn, ionizing radiation please? njh 23:11, 2 January 2006 (UTC)

The EM Radhaz article notes that a burn can result from touching an antenna. I guess that assumes that the power/voltage is high enough. See also[1]
The sentence quoted probably isn't related to the SWR article, probably should be removed. I'm not sure what it means by abnormally high, 2 w from a 1 w system would be abnormally high, but not likely to cause a burn. Maybe it's there because if you touch an antenna it will create high VSWR? Maybe just delete it from this article. Someone can add it again later if they have a reference for it. --Dual Freq 00:08, 3 January 2006 (UTC)

Agreed rf burns have little to do with SWR, essentially a RF burn is caused by radio waved heating the body tissues (in a similar manner that a microwave heats foods) touching the antenna directly increases this effect, also has alot to do with resonant frequency of various parts of the body to calculate absorbtion and heating, ARRL has alot of good litterature on burns. Mattpalmer84 15:00, 19 May 2006 (UTC)

[edit] Standing Wave Math Expression

It seems being a paradox. For

\mathcal {\mid}\Psi(x,t){\mid}^2=A^2sin^{2}(kx)*cos^{2}({\omega}t)=0 {\neq}1

which means that it does not equal to 1. Thus caused not coresponse Normalization. Known a standing wave is expressed as

\mathcal, \Psi(x,t)=Asin(kx)*cos({\omega}t), .

Can anyone talk about your thoughts? Thanks.

By their math expression we can clearly find angular frequency of \mathcal V_p , \mathcal \omega which keeps constant when a wave vibrates up and down localized. That may because of energy transports into a wave is conservative,just like a particel moves up and down in a Y axis,localizedly(which keeps energy conservative).
But for another one,it travels in an X axis,that hints its phase-angular is the function of time. By time changes,then \mathcal \omega naturely changes either.

I'm a little not sure above. Could anyone discuss with me? --HydrogenSu 11:47, 7 February 2006 (UTC)

my opinion is that is something for a physicist to explain, i would rather consider the practical realitys of EE problems Mattpalmer84 15:05, 19 May 2006 (UTC)

[edit] Arcing

The article says "Arcing may occur if there is a hole, if transmitting at high power, usually 200 watts or more (Need reference for the power statement)." I doubt a reference for the power statement can be found as arcing strongly depends on the frequency and the waveguide dimensions. I frequently transmit between 2 and 3 kW through a R26 waveguide at 2.45 GHz and have never experienced any arcing. In my opinion, the sentence should be shortened to "Arcing may occur if there is a hole or if transmitting at excessive power."

Ulrich

[edit] Error in claim in section "Practical implications of SWR"

The following claim mentioned in "Practical implications of SWR" is not true:

  1. Higher reflected power in the transmission line is dissipated in the output stage of the RF source, in the form of heat.

This is extensively documented in the ARRL Techical Information Service at http://www.arrl.org/tis/info/reflections.html

See http://www.arrl.org/tis/info/pdf/q1106037.pdf.

Regards, LA8UU

—Preceding unsigned comment added by Oka (talk • contribs) 18:40, 20 February 2008 (UTC)

Well if the power is reflected, where do you figure it eventually goes? And it's a pretty well-accepted fact that running an unloaded microwave oven cooks the magnetron precisely because the magnetron ends up dissipating the power that is reflected rather than absorbed by the cooking chamber.
Atlant (talk) 00:24, 22 February 2008 (UTC)