I can see how the vectors might cancel out if you have two identical
antennas mounted the exact same way and pointed in the same direction on
either side of the mast but ONLY with a wind blowing STRAIGHT DOWN from
the sky to the top of the mast, and not in any compass direction from 0
to 360. This is extremely unlikely, even during a down-burst.
Other than that I agree with the others who have said they do not see
how mounting antennas on either side of the mast vs. on the same side of
the mast helps in any way. When the wind blows from any direction other
than exactly parallel to the mast, the total vector forces should be the
same as if both antennas were mounted on the same side of the mast. The
elements and boom are of the same length, weight and materials so they
should be subject to the same vector forces.
73
Bob, KQ2M
On 2023-09-18 20:16, john@kk9a.com wrote:
If this is supposed to reduce twisting forces or stress on the mast
(other
than from weight being on one side), I never understood this concept.
I
wish there was a photo or video that explained this. All of my large
Yagis
have always been bolted on the same side of the mast or tower.
John KK9A
Steve Maki K8LX wrote:
That's what I used to think, but when shown how the vectors all cancel
out when the elements AND boom are mounted at their exact centers, I
became convinced otherwise. Of course boom to mast clamps are often not
at the boom center, so that throws things off a bit.
-Steve K8LX
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