There IS one way to do a 2-element multiband vertical array, and that is
described on pp. 10ff of the ARRL antenna compendium, volume 2. Most of
the patterns are bidirectional, and the control scheme is fairly
complicated. Also, there's no claim for gain, but the arrangement can
produce some pretty deep nulls over a good ground radial plane, so it might
actually be a useful idea for a receiving antenna.
The ability to change directions quickly isn't a high priority to me. If
you use short-boom tribanders (perhaps a stack), the F/B ratio isn't very
large anyway, and the front lobe is fairly broad, so, for example, pointing
20 degrees from here quite adequately paints Europe and continental Asia at
the same time. The stations in the Caribbean and South/Central America
tend to be loud enough to work off the back as they turn up, and in the
meantime I have forward gain that is well beyond anything that can be
expected from a vertical array, if only because of ground reflection gain.
73, Pete Smith N4ZR
"That's WEST Virginia. Thanks and 73"
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