[TowerTalk] Choke on feed point of dipole

[Jim Lux]

Actually, what you do is run the feedline up through the bottom element (which is a tube). And then choke it at the bottom of that element. 
It makes what's also called a "sleeve dipole" 
And yes, the presence of the feedline near the end of the dipole does introduce potential issues

Eh, what we need is coax with 31 mix in the jacket self choking feedline- I've actually looked into how one would make something like this for work - an antenna laying on the surface of the Moon for broadband usage without weird lobes)


On Mon, 12 Jan 2026 22:16:34 -0700, Tom Hellem <tom.hellem at gmail.com> wrote:

My hat is off to all of you fine gentlemen who contributed to this
discussion.
You have helped me see the light.
I think the reasonable conclusion is that a center fed vertical dipole is
a very difficult thing to make work, especially if the feedline cannot be
brought away from the antenna horizontally for an appreciable distance.
I’m going to try base feeding it with an LC network and see if I can get
better results.
Many thanks to everyone who provided input.

Tom
K0SN

On Mon, Jan 12, 2026 at 6:57 PM Jim Brown  wrote:

> On 1/12/2026 5:23 PM, Jeff Blaine wrote:
> > Tom, I'm emphasizing what Jim mentioned earlier. If the antenna
> > resonant point moved by adding the choke, then that means the feedline
> > was participating to some extent as "part of the antenna."
>
> Yes, but in Tom's configuration, even with the world's greatest choke,
> the feedline can still be a parasitic element.
> >
> > My belief is that without a feedline choke, you simply cannot guarantee
> > that the feedline will not participate. So every antenna here (19 of
> > them) has a feedline choke of some form.
>
> Yes. And feedline chokes also reduce interstation interference, whether
> SO2R or multi.
>
> 73, Jim K9YC
>
>
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