N2EA has it right!
After I ran the test on the R7000 I had an exchange of notes with W1JR who
was the original designer. He pointed out that there is no "other half of
the dipole". It is loaded in such a way as to be complete.
My test was with the capacitive hat (the short radial rods) at the lower end
of the antenna about 12" off ground.
While I didn't check it out on all the higher bands, it appears to me that
it's a pretty good antenna for those with space limitations.
The point of my initial comment was that, with careful design, it is
possible to get reasonable performance from a vertical which doesn't have a
large radial system either on the ground or up in the air. The most extreme
example would be a simple full size vertical dipole. As you shorten down
from the full 1/2-wave dipole there are reasonably efficient loading schemes
which can be used to approximate the dipole.
73, Rudy N6LF
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