RadioBanter - Effect of raising vertical antenna higher

I don't know the minimum height above ground (in wave lengths) that
make the improvement in an antenna. However, Steppir antennas says
that an antenna on the ground needs 120 radials just to match one in
the air with two radials. I would like to know where the noticable
benefit of raising an antenna above the ground actually takes place
and where is the maximum benefit.

I know that the higher the better, but rather than that kind of
benefit, I am wondering from a ground standpoint where the benefits
start and where the point of diminishing returns begins.

Thank you to everyone who answered my question.

The reason I asked is because I am designing a vertical that can be
ported to a location and setup as a single band vertical for whatever
band is desired at the time. I was wondering if I could raise it
about ten feet or so and use radials as guy wires to get a better
effect than laying it on the ground. I figured I might could get away
with using 4 to six radials and have an improvement.

I am still not sure of the answer, but I think I have figured out that
if I use six radials at ten feet, it will still be better than 6
radials on the ground. Of course, I am wondering if I will be able to
use more than three or four radials at the time.

Thanks again.

--
73 for now
Buck
N4PGW