Sorry guys, but coupling doesn't change if the element is above or in
the same plane of the other.
It only changes and reduces, the coupling, if the elements are normal
to each other or the distance increases.
Parallel parasitic elements of comparable lenght a few feet from each
other do interact and destroy gain and directivity of both antennas if
not kept under control properly.
Just as an example, a 12m director is perfectly seen by 10m and should
be behind and far a 10m reflector, unfortunately a 10m reflector is
seen as a sort of 12 director and shouldn't be placed ahead of a 12m
element.
73,
Mauri I4JMY
>
> G3JVC....what VK6APK, Alek, said is quite right. Placing 'em on
> the same boom will bring the interactions under control. There
> will still be some mutual coupling and detuning that takes place,
> but that's more controllable than the spaced situation.
>
> That said, however, I've put a 20,15,10 about ten feet above a
> 17, 12 meter yagi, and had them both work. They took power, and
> appeared to have a front to back ratio. Were their patterns
> degraded by the proximity of the other? Undoubtedly, to some
> degree. My last solution was to move to a Log Periodic, with
> which I've been quite pleased.
>
> Mine seems to be a minority opinion, however. Asking your question
> again on towertalk@contesting.com might yield both opinion and
> information. Perhaps even illumination.
>
> Regards,
> Jim Jarvis, n2ea
> Essex Vermont
>
>
>
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