> If the SWR or the resonance of the antenna changes with
feedline changes,
> you have common-mode current on the feedline. Ground are
important as well.
Actually it can mean three things John.
1.) The antenna impedance and SWR is actually changing
because the feedline is part of the radiating system
(feedline acting like an antenna)
2.) The SWR bridge null adjustment and the feedline are not
the same impedance (a meter nulled for 55 ohms will change
SWR when moved along a 50 ohm feedline if that 50 ohm line
has standing waves)
3.) The cable or shield connections are bad.
A ground on coax really isn't important if the feedline
connections are good and the antenna is perfectly unbalanced
or has a properly designed interface.
73 Tom
_______________________________________________
See: http://www.mscomputer.com for "Self Supporting Towers", "Wireless Weather
Stations", and lot's more. Call Toll Free, 1-800-333-9041 with any questions
and ask for Sherman, W2FLA.
_______________________________________________
TowerTalk mailing list
TowerTalk@contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk
|