KSWR=1.1?

Not sure why you have KSWR, as far as I'm aware its only known as VSWR for Voltage Standing Wave Ratio.

The aim of reducing the VSWR is to obtain maximum power transfer from one place to another, if the coax connection has an impedance of 50Ω and the transmitter and receiver have identical input and output impedances of 50Ω, You will get maximum power transfer without any standing waves causing distortion of the waveform.

The VSWR is a measure of this impedance mis-match.

John.

In addition to the above, the energy is not "lost". It is simply "not transferred".

it also depends on the power levels. In a high power system you want the VSWR as low as possible to avoid peak voltages and losses from higher circulating currents.

http://www.antennex.com/preview/vswr.htm

22.04.08

Many thanks to all who gave me attention.

But not the dependence of power losses in transmission line invoked by mentioned SWR is the heart of the problem. As it is well known (e.g. http://www.arrl.org/tis/info/pdf/0404034.pdf (p. 35) or http://www.codaros.com/images/news/newsletter_images_0806/Effects%20of%20VSWR.pdf or http://www.procom-dk.com/techinfo/e0204-swr-mismatch-loss - sorry, link no longer available - etc.) these losses till the rather considerable VSWR values (>3!) are not extremely large. Moreover, very often not this effect (the power loss caused by reflections in transmission line) is the main reason of errors in received data. More frequently, it is in frequency and phase nonlinearities caused by transmission line mismatched impedances. These nonlinearities narrow the undistorted signal bandwidth and reduce data transfer speed.

I am searching for information about permissible VSWR magnitudes in receiving antenna's feeder line for different modes of modulation or the analytical procedure for this investigation.

Please, advise me the books or other sources of information where data distortions caused by mismatch in the feeder line are analyzed.

Well why didn't you ask that in the first place?

John.

VSWR is important in transmission line losses as the energy sloshes back and forth between the two ends due the mismatch. Any energy not delivered in the first pass is subject to these, repeated losses. Do not be mistaken, this is just as significant at reception as in transmission. How much is bad = how much you can take?!?

I would start reading the ARRL Handbook from any year.

The other aspect is, that many transmitters cannot take the peak voltages of high VSWR. If you are lucky, your transmitter just throttles back. If not, it blows, or arces and blows. I would guess, that may mess up your day.

"He, who has ears to hear, let him hear!"

Dear colleague I am grateful for your comments.

Of course the reducing of reflected waves (the low value of K_s≡VSWR) in a transmission line is very desirable from different points of view. But it is hardly reachable in wide frequency band and demands the additional costs. It is better not to go beyond the necessary and sufficient amount. In my first post I bore in mind that difference in direct energy/power losses is not considerable for reliability of data reception when K_s grows for example from 1 till 3. And in my second one I tried to clarify this conception.

Can anybody among specialists advise me any (Internet - reachable preferable!) information (reference sources) where data distortions caused by mismatch in the feeder line are analyzed?