Ed,
You're right, I am 'confusing' omnidirectional with
'omniazimuthal'(?). But, I think if you consider the common
use (or misuse), what I said does hold together. One
example of a vertical array as I was trying to describe is
the 'Ringo Ranger'(2 el.), which is quoted as being
'omnidirectional',
and does have gain over a single element antenna.
As for signals directly overhead, I've never had much
need in receiving them (don't 'do' much VHF/UHF where it may
be desired). And since it's obvious that you knew what I was
referring to, I'm assuming your post is intended to correct my
mis-description. For that I thank you...
'Doc