TEM stands for transverse electro-magnetic. It means that both the
electric (E) and magnetic (H) fields are transverse (at a right angle)
to the direction of propagation. It refers only to the orientation of
the fields relative to the direction of propagation.

A time-varying E field is never "all alone" -- it's always accompanied
by an H field. Consequently, a voltage wave on a transmission line is
always accompanied by a current wave. I'm certain that Keith didn't mean
to imply otherwise.

Roy Lewallen, W7EL

Richard Harrison wrote:
. . .
Keith also wrote:
"It is a voltage wave which does the travelling."

Sure. That`s why it is called a TEM wave. The E-field is all alone.

Best regards, Richard Harrison, KB5WZI