On 29 Mar 2007 13:10:46 -0700, "billcalley"
wrote:

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.

Hi Bill,

As a short description, that is adequate.

But then why does the concept of "mismatch loss" exist in
reference to antennas?

"Mismatch loss" is a system description, not an antenna description.
So your reference is wrong.

I have quickly calculated that if a
transmitter outputs 100 watts, and the TX antenna has an impedance
that will cause a VSWR of 10:1 -- using lossless transmission line --
that the mismatch loss in this "lossless" system would be 4.81dB!
(Reflected power 66.9 watts, RL -1.74).

Two things wrong he
1. You say nothing of a tuner inline;
B. Your math is wrong either way.

Since mismatch loss is the "amount of power lost due to
reflection", and is as if an "attenuator with a value of the mismatch
loss where placed in series with the transmission line", then I would
think that VSWR would *definitely* matter, and not just for highly
lossy lines either.

It does matter if you lack a tuner (in more ways that one). Most
discussion of "mismatch loss" omits such matters as tuners as it is a
separable issue. Combining these topics raises your chance of
confusion.

73's
Richard Clark, KB7QHC