It would be subpar because of excess ground losses #1. You only have
one radial,
and the antenna is low to the ground.
As far as radiation in one direction, I agree with Roy. It would
probably be
about the same in that direction as another "poorly grounded" antenna,
except
that in the other directions, it would be even worse. I think in the
real world,
you will find it to be hardly directive at all. Or at least enough to
be useful
anyway...To be really directive, a vertical system needs multi
elements.
IE: phased verticals, bobtail curtains, etc...A bobtail curtain is a
mean antenna
on 40m at night. Only the curtains, and the few lucky dogs running
yagi's could
beat my elevated ground plane to VK land late at night. A friend of
mine across
town ran a bobtail curtain. He could dog my GP most every night. But
he's got
three elements compared to my one... MK