I've used 3 element 90 degree spaced vertical arrays in the past,
driving 2 out of 3, running matched, equal length
feedlines to each vertical, and using one 90 degree
phasing line. Worked fine, and gave decent f/b in 6 directions.
Here's a modelling/measuring problem, which perhaps some TT'er has
The third element is parasitically coupled to the driven pair, and
therefore should affect the pattern. I never had an operating impedance
bridge for 7MHz, which would allow me to intentionally detune the
third element. So I took the empirical approach...just put it up and
noted performance. Seemed ok.
And the question: Has anyone considered the third tower decoupling
problem? Is it possible that having the 'right' length of feedline
would effectively decouple the tower at the operating freq. Maybe I
got lucky. Has anyone modelled such an array?
Here's another possible use-case:
We know that you can feed sloping dipole arrays from a central tower,
through 3/8 wavelength feedlines to a central switch. The reactance
of the feedlines makes the un-fed dipoles appear long...and act as
reflectors. Why couldn't that be done with verticals, as well?
Not as predictable a pattern as a 90 degree spaced, 90 degree fed pair..
but perhaps useful just the same. Thoughts?
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