According to Fermat's principle, the beam changes its direction of propagation
in the plasma channel.
Along the direction of propagation
, the volume turns a little for each step, and then projects again.
The result is that no clear tonotopicity is produced, but the high-frequency components are still slightly attenuated along the direction of propagation
The phase shift transverse to the direction of the propagation is kept fixed while the phase shift along the direction of propagation
This is the dual-curvature lensing that we were looking for: the particles are emitted by the same source but their detection manifests a different direction of propagation
. From the fact that the soft particle goes through D and Camilla and the hard particle goes through D' and Camilla one easily finds that the angle [theta] characterizing the difference in their observed directions of propagation is given by
Further, as the electromagnetic waves propagate, the energy also flows along the direction of propagation
. The translational energy flow implies the existence of additional orbital angular momentum.
As seen in Figure 1, the direction of propagation
from AE source to AE sensor will substantially differ in large scale composite components when compared to the frequently used 1D-like arrangements in coupon testing.
Using the "right hand rule," with the index finger of the right hand pointing in the direction of the electric field (down) and the middle finger pointing in the direction of the magnetic field (into the paper), your thumb will point in the direction of propagation
(to the right).
Plane wave solutions to Maxwell's Equations combined with the above constitutive form produce two modes of propagation and two, possibly degenerate, phase velocities for each direction of propagation
. In conventional isotropic materials, these modes are electrically and magnetically polarized perpendicular to the direction of wave propagation and are often referred to as the transverse electric and transverse magnetic modes.
Usually, the light oscillates in a plane perpendicular to its direction of propagation
. If the oscillation is circular, this is similar to the motion of an airplane propeller.
In Love-type waves, there is no particle motion in the vertical plane but particle motion takes place in the horizontal plane only and it is transverse to the direction of propagation
. Chattopadhyay  derived his idea on the dispersion equation for Love wave due to irregularity in the thickness of non-homogeneous crustal layer.
The Cartesian coordinate system (x, y, z) is chosen with z-axes taken vertically downward in the half-space and v-axes is chosen parallel to the layer in the direction of propagation
of the disturbance.