[TowerTalk] Choke on feed point of dipole

[Jeff Blaine]

I would not hesitate to put up a vertical dipole.

In fact my 30m beam is so directional I'm thinking of putting up one 
here just to cut down on rotor wear & tear.  Assuming you have the 
height, It's much simpler physically than doing a vertical as you don't 
have the ground system to worry about.  And it gets the important 
current maximum quite a way off the ground.

The "easy" way to do this is to build the dipole as normal. **NO** choke 
at the feepoint in this case.  The **GROUND** leg of the dipole runs 
down to ground, next to the coax with the two secured together so they 
are not blowing around separately.

The important part is to put a serious coax choke at the end of the 
dipole tip, on the ground side.  That means multiple turns through a 
couple of type-31 ferrites.

Antenna resonance is trimmed with the tip length at the top assuming you 
have a pulley to pull it up.

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

On 1/13/2026 4:02 AM, Brian Beezley wrote:
> Tom Hellem wrote:
>
> "I think the reasonable conclusion is that a center fed vertical 
> dipole is a very difficult thing to make work..."
>
> Tom, at my last QTH I dropped a 40m dipole vertically from a tall 
> eucalyptus. I fed it directly with RG-58 (no choke). The feedline ran 
> roughly horizontal for tens of feet. (The tree was slightly down the 
> slope of a hill from the shack.) SWR was fine. I remember generating 
> pileups during Field Day as a 500 watt home station, but otherwise I 
> was not that impressed with its performance.
>
> The gain and elevation pattern of a vertical antenna are quite 
> sensitive to ground quality. Unless you have really good ground, a 
> horizontal antenna may perform better, even at low angles, if you can 
> put it at a decent height. "Decent" might not be that difficult at 14 
> MHz and above, but it may be a problem below.
>
> When modeling a vertical antenna, these generic ground constants are 
> much more appropriate than those your antenna analysis program offers:
>
> https://k6sti.neocities.org/hfgc
>
> Brian
>
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