John Ferrell wrote:

Here is a bit I ran across the other day...

I copied this out of the MFJ-269 antenna analyzer manual:
"Resonance at the feedpoint only repeats when a mismatched feedline is
an exact multiple of 1/4 wl. If the line is not an exact multiple of
1/4 wl, the resonant frequency of the antenna might be shifted higher
or lower by the transmission line. A mismatched line that is not an
exact multiple of a quarter-wavelength adds reactance that can either
cancel antenna reactance at frequencies where the antenna is not
resonant, or add reactance at frequencies where the antenna is
resonant."

My deduction:

In essence, if the feedline is matched there is no problem. If it is a
multiple of 1/4 wave in length there is still no problem! Trying to do
both is a good idea.

Your deduction is not 100% valid. 1/4WL can be a BIG problem and
worst case for matching.

I guess MFJ is technically correct but confusing. For instance,
assume a 50 ohm antenna and 1/4WL of 600 ohm open-wire line. The
"resonant" impedance seen looking into the feedline would be 7200
ohms, outside the matching range for a lot of MFJ tuners. Half a
century ago, we called that the "anti-resonant" point (akin to a
parallel resonant impedance). Most amateur radio operators should
substitute 1/2WL for 1/4WL in the above MFJ manual quote to avoid
thinking 1/4WL is "no problem".
--
73, Cecil http://www.qsl.net/w5dxp