[Antennas] T match

2003年6月24日 23:47:09 -0000

Ok, if you are really into balanced line that makes T matches easy...
I'm having a hard time trying to picture what would happen with a split
de fed that way. Normally I would look at an old telrex design where
the de is through the boom and the T sides are fed with a coax balun...
the shields of all the coax are connected to the boom in this case,
though theoretically they probably don't have to be... and the center of
the de is of course connected to the boom so they are all theoretically
at the same 'ground' potential. Now feeding it with balanced line to
the T should theoretically result in the same condition where the split
ends of the de have essentially zero voltage... I know this should be
true, but still I would connect the split ends to the boom. If nothing
else this would provide a dc ground for the de and may reduce static
build up and provide a path for lightning besides down the feedline to
the shack.
I do rather like the telrex feed system, simple construction
mechanically and electrically with no capacitors to bother with, and a
simple 1/2 wave coax balun to get a 50 ohm coax feed... and all at dc
ground.
David Robbins K1TTT
e-mail: mailto:[email protected]
web: http://www.k1ttt.net
AR-Cluster node: 145.69MHz or telnet://dxc.k1ttt.net

> -----Original Message-----
> From: [email protected] [mailto:antennas-
> [email protected]] On Behalf Of Steve L.
> Sent: Tuesday, June 24, 2003 22:22
> To: David Robbins K1TTT; [email protected]
> Subject: RE: [Antennas] T match
>> Hi,
>> To be more specific, I normally design and build
> monoband HF yagis with a continuous DE and T-match to
> get 200Ohms and feed with 450 Ohm balanced line to a
> transmatch in the shack.
>> I have an existing yagi with a split DE that I want to
> feed in this way by adding a T match and feeding w/
> balance line. Alternately I'm looking for the best way
> to use balanced line and feed this antenna.
>> I go for a 200 Ohm feedpoint to allow using a 4:1
> balun at the feedpoint and feeding with coax as an
> option (although I never actually DO this).
>> 73, Steve N4SL
>> --- David Robbins K1TTT <[email protected]> wrote:
> > >
> > > I've used T matches on Yagis quite a bit with good
> > > success, but always with a continuous DE, not
> > split.
> > >
> > > Hmmm.... can I use a T match on a split DE?
> >
> > I suppose you probably could. It would be more
> > trouble construction
> > wise than just having a solid element and shouldn't
> > really change the
> > performance as the inside end would essentially be
> > grounded on each side
> > but through the coax instead of directly to the
> > boom..
> >
> > David Robbins K1TTT
> > e-mail: mailto:[email protected]
> > web: http://www.k1ttt.net
> > AR-Cluster node: 145.69MHz or telnet://dxc.k1ttt.net
> >
> >
> >
> >
> > - - -
> >
> > Your moderator for this list is:
> > Larry Wilson KE1HZ [email protected]
> > _______________________________________________
> > Antennas mailing list
> > [email protected]
> > http://mailman.qth.net/mailman/listinfo/antennas
>>> __________________________________
> Do you Yahoo!?
> SBC Yahoo! DSL - Now only 29ドル.95 per month!
> http://sbc.yahoo.com
> - - -
>> Your moderator for this list is:
> Larry Wilson KE1HZ [email protected]
> _______________________________________________
> Antennas mailing list
> [email protected]
> http://mailman.qth.net/mailman/listinfo/antennas