[TowerTalk] Choke on feed point of dipole

[Jeff Blaine]

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."

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.

73/jeff/ac0c
alpha-charlie-zero-charlie
www.ac0c.com

On 1/12/2026 6:35 PM, Jim Brown wrote:
> On 1/12/2026 4:15 PM, Tom Hellem wrote:
>> I'm doing exactly that.
>> But The horizontal portion of my feedline as it leads away from
>> the vertical dipole is not exactly horizontal, it drops down
>> at maybe a 30 degree angle for about 8' , then it drops
>> straight down vertically to the ground.
>> I am getting the feeling this could be part or all of the problem.
>
> Yes. That's what I meant when I observed that the feedline becomes 
> part of the antenna. It would be pretty easy to model in NEC -- all 
> you need are the endpoints of straight portions of the run, and an 
> approximation would be enough to show proof of concept.
>
> 73, Jim K9YC
>
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