[Antennas] Feeding vertical triband dipole

[Chris Boone]

Igor,
A coaxial choke or even ferrite cores on the coax taped together to form a
long continuous bead would do...a balun at the FEED Point won't do only
because you have half the vertical dipole around it (the sleeve); if the
coax was coming away at 90deg, it would if it was a 1:1 current balun..Put
the coax choke (several, say 7-10, turns of COAX around a 3-5in diameter
taped together), or the ferrite cores, RIGHT below the sleeve's end...that
will kill any radiation on the outer shield of the coax...and should work ok
for you.

Chris
WB5ITT
EL39

-----Original Message-----
From: antennas-bounces at mailman.qth.net
[mailto:antennas-bounces at mailman.qth.net] On Behalf Of Igor Sokolov
Sent: Monday, May 25, 2009 9:09 PM
To: Antennas at mailman.qth.net
Subject: [Antennas] Feeding vertical triband dipole

I wonder if someone can suggest the way to decouple  feeder from vertical 
triband dipole. The dipole is 20-15-10 sleeve feed dipole which I need to 
feed with 50 ohm coax. The feeder cannot be made leaving antenna at 90 
degrees for some reasons. In fact feeder will go down along the mast (and 
one of the shoulders of the dipole). Is there anything I can do to decouple 
feeder from the antenna. As I understand single balun at the feed point 
would not be enough here.

73, Igor UA9CDC