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.

John Ferrell, W8CCW

On Sun, 06 Nov 2005 13:07:14 -0800, Dan Richardson wrote:

On Sun, 6 Nov 2005 15:43:14 -0500, "garigue"
wrote:

Hello all ....I have seen some where a list of what length of feedline to
avoid resonance wise....... Does anyone know the site ?? I will be
using 450 twin for the antenna .....never used open wire feed in my 40 years
in this endeavor. Thanks in advance ......

You need only the length of line necessary to make from you rig/tuner
to the antenna. The are some cases that the line length may result
difficulty matching. If so, just add a few feet. Don't worry about
resonance.

73,
Danny, K6MHE

email: k6mheatarrldotnet
http://www.k6mhe.com/