On Friday, July 17, 2020, 7:10:32 PM CDT, Kurt Pawlikowski <ku...@pinrod.com>
wrote:
> Ken: In some respects, a "matching device" at the base of the antenna is a
> tuner! {'-) It accomplishes the same function... {'-) k
> WB9FMC
On Friday, July 17, 2020, 08:21:54 PM EDT, Ken Roberson via Elecraft
<elecraft@mailman.qth.net> wrote:
> Kurt,
> We are not tuning the antenna , we are matching the antenna to the coax at
> the base of the antenna.
> 73 Ken K5DNL
Kurt's correct. A low-loss (non-resistive) matching network connected directly
at the feedpoint of an antenna will modify its resonant frequency.
A matching network connected to the feedpoint of an antenna through 1 inch
(25.4mm) of transmission line will also modify the resonant frequency of the
antenna.
A matching network connected through 1 meter of transmission line will also
modify the resonant frequency of the antenna.
A matching network connected through 10 meters of transmission line will also
modify the resonant frequency of the antenna.
And so on, and so forth... all the way back to the shack! ;-)
Why? Because transmission lines obey reciprocity. As such they cannot (aside
from the effects of losses) separate what's on their source end from what's on
their load end. What you do to one end directly affects the other, and vice
versa.
Show me a transmission line that disobeys this property, and I'll show you a
line that is either opened or shorted.
So, yes, a non-resistive matching network in the shack will bring your antenna
SYSTEM (antenna + transmission line) into resonance at your operating
frequency. In the process, the resonant frequency of the antenna is modified,
as well.
73 de John, KD2BD
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