On Thu, 11 Feb 2010 07:59:23 -0800 (PST), phaedrus
wrote:

How much is the signal speed retarded by typically and are there any
circumstances where we need to be concerned about this phenomenon?

Look up the velocity factor, a simple multiplier/divider of the
relative speed of light in a transmission line. This means that the
signal that hits your antenna will hit your radio over the air before
that same signal reaches it through the transmission line.

73's
Richard Clark, KB7QHC