  We discuss applications of the quantile concept of trajectories and
velocities to the propagation of electromagnetic signals in wave guides of
varying cross section. Quantile motion is a general description of the
transport properties of measurable conserved quantities in quantum mechanics as
well as in classical electrodynamics. In the latter case we consider the
quantile motion of electromagnetic energy as the direct result of a physical
measurement. In this sense the quantile velocity corresponds to the
electromagnetic signal velocity also in the presence of barriers and
inhomogeneities in the medium of propagation. We show that this signal velocity
is always smaller than the speed of light in vacuum. Using numerical examples
we demonstrate how typical wave phenomena can be described in terms of the
quantile motion.
