Just a follow up to Jim's comments:
> SUMMARY - A matched antenna will significantly outperform a
> mismatched antenna with a tuner. A tuner cannot introduce
"reflection
> gain" to change this fact.
>That summary is not correct!! Other wise most broadcast stations,
>most of which use antenna tuners would be wasting a lot of money!!
>Their vertical radiating towers are not 1/4 wave tall, in most
cases,
>forexample.
This statement is made without any background information. To have an
adequate discussion on the performance of broadcast stations, we would
have to know the transmitter output power, the tuner loss, the total
cable attenuation, the antenna VSWR, the antenna pattern, the antenna
gain, the communications distance, the reciever sensitivity, etc.,
etc.
Also, I never once said that a tuner does not the improve performance
of a mismatched antenna.
>In this overly wordy argument put forth by Steve, he omits one tiny
>detail: the tiny amount of time that these reflections within the
>transmission line between the antenna and the tuning network exist,
>both initial and following about which he belabors!
>These reflections are over and done with in nanoseconds, in even
>the
>lowest propagation velocity coax where the speed of the signal is
>only 60 some % of the speed of light in space!
I do not disagree with Jim's statement about the short time involved
for all of the voltage reflections and interactions to occur. The
real issue is that they occur. Their practical impact on signal
quality in amateur communications may not be significant but the
re-reflections at the antenna are still echoes of previous signals.
The background theory and operation of a tuner does not change because
the time involved is short.
As far as my summary regarding a matched antenna performing better
than a mismatched antenna and tuner: First, if the cable attenutaion
between the tuner and the antenna is 0 dB, then a signal strength
meter will not detect the power difference as Jim stated. This is not
inconsistent with any statements I made in my previous e-mail.
However, as the cable attenuation increases, a field strength meter
should be able to detect the difference between the two set ups. This
would be the best experiment to verify what really happens.
73 Steve Best, VE9SRB
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