Cecil Moore wrote:
John Popelish wrote:

As far as the center conductor is concerned, the shield is the entire
universe.


My point exactly! There is no third path to the outside
world but the standing waves do exist inside the coax
without it.

But from the concept of a standing wave producing a current
distribution along the center conductor, the shield performs the
function of ground. One current path is along the center conductor
(in one of two directions) and the other current path is through the
dielectric to the shield, in proportion to the rate of change of
voltage at any point on the center conductor.

If you eliminate the shield and have a single wire carrying a standing
wave over a distant ground, the capacitance per foot drops (raising
the characteristic impedance of the transmission line, and losing
energy to EM waves, but the displacement current is still there in
proportion to the capacitance per foot and the rate of charge of
voltage. There is nothing inherently different. Only the loss and
ratio of L/C per foot changes.