[Antennas] From transmission lines to tuners
Pat W
[email protected]
2002年12月19日 09:08:08 -0800 (PST)
The whole subject gets complicated really fast. My
best guess is that an SWR of < 1.5:1 at the tuner side
will have more loss in the tuner trying to tune it out.
I started to give a presentation at my local Ham Radio
club on this subject but it got bogged down in a hurry.
All wires carrying RF act as transformers, including
the antenna. IF the input Zin = the feedline Z0, then
the SWR stays the same(less losses) from the load to
the input. If the input Zin is not = to the feedline
Z0, the SWR still stays constant across the feedline
but the SWR at the input is now different because its
internal Z0 is not the same. That's why we need a
tuner with open wire line(unless the line length is
selected for a correct transformation to 50 ohms).
Is this confusing enough??
Pat W0OPW
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