Denny wrote:
Hmm, that is new to me Roy... So what is the professional term for the
velocity of a wave propagating along an unterminated antenna wire?

The velocity is simply the speed of light if the wire is uninsulated
(except, of course, for traveling wave antennas like a Beverage, where
transmission line type analysis and "velocity factor" are appropriate).
Analysis of antennas made from insulated wire is rare, and perhaps
"velocity factor" is used in that case.

When using a transmission line analogy to explain antenna operation
(more-or-less but not completely accurately), the model usually assumes
speed of light propagation along the line, then a load at the end which
effects the shortening of the resonant length.

. . .

Roy Lewallen, W7EL