On Tue, 23 Sep 2003 14:15:17 -0500, Cecil Moore
wrote:

Richard Clark wrote:
You would have a harder time tuning a 20M dipole to 10M.

Why? An odd number of quarter-wavelengths of ladder-line will
result in a near-perfect match.

Cecil, I have a 44-foot dipole with 42 feet of ladder line -- I can
tune it for 30m-10m easily with my tuner. I can't get it to tune on
40m, though. If I shorten the ladder line to 33 feet, or lengthen it
to 99 feet, would that give me a near-perfect match on what is a 3/8
wave dipole for 40m?

Tnx,

Bob
k5qwg

On Tue, 23 Sep 2003 22:58:03 -0500, Cecil Moore
wrote:



In general, to use the variable ladder-line length approach that I use,
a dipole needs to be at least 1/2WL on the lowest frequency of operation.
For dipoles shorter than 1/2WL, as the dipole is made shorter, the resistance
goes down and the reactance goes up, causing the resistance at a current
maximum point to go lower and lower with increasing SWR.

Thanks, it just sounds like I need to make the antenna longer :-)

Bob
k5qwg