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Old March 29th 07, 10:10 PM posted to sci.electronics.design,sci.electronics.basics,rec.radio.amateur.antenna
Charles Schuler Charles Schuler is offline
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First recorded activity by RadioBanter: Mar 2007
Posts: 3
Default VSWR doesn't matter? But how about "mismatch loss"?


"billcalley" wrote in message
oups.com...
What I gleaned from the excellent answers for the original "VSWR
Doesn't Matter?" thread is that high VSWR doesn't really matter in a
lossless transmission line environment between a transmitter's antenna
tuner and the antenna, since any reflected RF energy will simply
continue to "bounce" back and forth between the tuner's output
impedance and the antenna's input impedance until it is, finally,
completely radiated from the antenna without loss.


That's basically true but ignores the stress that can be placed on the
output circuit of the transmitter. Why do you think VSWR shut-down circuits
are so popular? One can see rather high voltages or currents that are
potentially damaging to the transistors and capacitors.

Now, since "lossless" is an abstraction and all materials have voltage and
current limits, just make this easy on yourself and always strive for a VSWR
of 2:1 or less. It simply works better and is more reliable.