The source of the r-f current flowing on buried radials is the r-f
current flowing in the earth as a result of radiation from the vertical
monopole. (etc)
It seems to me that answer ignores other effects.
1.) If we remove the earth, the radials still have current.
Yes, but then the origin of that current is via a direct, metallic path
back to the 2nd terminal of the source (transmitter), using either
balanced or coaxial transmission line.
I doubt any system is 100% pure with a boundary condition like a hard
switch.
Dirt is not the same everywhere, even at one location. It probably is almost
never the same at the surface as it is a few inches down.
Arbitrarily declaring the method current gets into the wire is a single
method determined entirely by contact or no contact is completely illogical.
The feedpoint connection, in all cases of vertical antennas, whether the
system is shunt fed or series fed, or even if it is an end-fed half wave,
ties one feed terminal to the ground or counterpoise system. It has to be
that way, and the current out into that counterpoise (whatever the
counterpoise is) has to be equal to the common mode current at the junction
flowing up into the radiator.
It can't be any other way.
Contact with the earth isn't like suddenly flipping a light switch, where
all of a sudden all of the current is magically "collected" from the dirt
all around the antenna, and then moving the wire .000001 wavelengths up
suddenly flips the switch the other way.
The only true case I can think of where virtually all of the current is
returned from the soil would be where the radial wire is buried several soil
skin depths below the surface. We can certainly have creative license to
**say** it is collected from the soil for any buried radial, but it pretty
clearly isn't factual unless the wire is infinitely deep in the soil so far
as skin depth goes.
73 Tom
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