I'm not an expert, although I play one on the internet! My guess is that it has to
do with the height above ground. I'm having a similar problem trying to tune
a hamstick dipole in my attic. Unfortunately the attic floor is insulated with
foil backed insulation, and no matter what length I make the antenna, it only
wants to resonate at 6.0 MHz. Changing the length does not significantly change
the resonance point, but does change the SWR dramatically.
--
John - WA2FZW
