> resistive with a purely reactive content. The bottom line is it
> doesn't matter. In a 2:1 environment, 88.9% of your power is still
> radiated by the antenna.
The worse thing anyone ever did to understanding how RF systems
work was present SWR as "match efficiency" or "percent reflected
That is absolutely incorrect Jon, unless you happen to be feeding
the antenna through a large attenuator pad that makes the rig look
like a 50 ohm dissipative resistive source and you are comparing
the additional mismatch loss in the situation where feedline loss is
very high or you have an intentional large 50 ohm attenuator in the
In a real system, anywhere from zero percent to 100% of the power
can be radiated with a 2:1 SWR. As a matter of fact, losses in the
transmission line and the rest of the system can DECREASE with
an increased SWR!
The tables in the Handbook and other places are only for
somewhat long lines compared to the wavelength, where there is a
place for waves "to stand".
SWR does not tell you at all what the efficiency of a system is,
because it does not indicate power dissipation nor does it tell you
anything about the source. It does not tell you the transfer
efficiency, unless the source appears as a conjugate with
dissipative resistance comprising the bulk of the loss.
There are cases where system efficiency increases with a
mismatch, cases where it remains the same, and cases where it
decreases. It depends on much more than the SWR.
73, Tom W8JI
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