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Re: [TowerTalk] Stacking Tribanders

Subject: Re: [TowerTalk] Stacking Tribanders
From: "Lux, Jim" <>
Date: Wed, 22 Jun 2022 12:00:55 -0700
List-post: <>
On 6/22/22 11:54 AM, David Gilbert wrote:

Great suggestion. Jim.

I ran HFTA for four conditions at 14 MHz over flat ground.

1.  two dipoles at 50 feet and 70 feet
2.  one dipole at 50 feet
3.  one dipole at 70 feet
4.  one dipole at 60 feet

The two dipoles at 50/70 feet show no additional lobes compared to the single dipoles.

The profile for the single dipole at 60 feet is IDENTICAL to the profile for the two dipoles at 50 feet and 70 feet except for a gain difference of 2.7 dB at every point on the curve.

All four curves are on the same plot.  The screen shot is available upon request.

I hope this puts the issue to rest once and for all.

Dave   AB7E

On 6/22/2022 11:10 AM, Lux, Jim wrote:
On 6/22/22 7:06 AM, Lux, Jim wrote:
On 6/22/22 12:18 AM, Jim Brown wrote:
On 6/21/2022 7:37 PM, Billy Cox wrote:
So outside of the cautions Dean shared, and used

We could do a simple experiment about what HFTA does - I tried it on my copy, but it's missing some .ocx (ancient version of HFTA from 20th edition) and trying to run it on Win10 under Parallels, which is sort of a "non optimal" environment.

That is, choose a pair of dipoles (for which it's easy to calculate the pattern) and flat terrain, and pick some different stacking distances to see what happens.

say I put a dipole at 50 feet and 70 feet.  Run the vertical pattern. Then run one by itself and the other by itself. The "dual" antenna configuration should have more lobes (because the spacing is 20 feet)

I was thinking that if you space them multiple wavelengths apart (do it at 10 meters), then you should get distinct grating lobes.   50 and 70 are about half wavelength, so I'm not sure about grating lobes.  two isotropes 1/2 wavelength apart don't make any lobes.


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