Electromagnetic Wave Propagation
1.1 PROPERTIES OF PLANE ELECTROMAGNETIC WAVE
1.1.1 Equation of Wave or Propagation
Electromagnetic waves are propagated in a vacuum, in dielectrics and conductors; here we will be interested in the propagation of radiated waves of periodic type that are characterized by a wavelength defined by a wave velocity which depends on the permittivity and permeability of the crossed medium.
Thus we consider a plane wave, as represented in Figure 1.1, propagating in direction x of an orthogonal reference system (x, y, z) while transporting the electric field E polarized in the direction y and the magnetic induction B in the direction z. The properties of such a wave can be deduced from Maxwell's equations, which link together the electric field E, the magnetic induction B, and the current density J:
where μ = absolute permeability of medium of propagation (H m−1)
ε = its absolute permittivity (F m−1)
These equations can also be written in differential form by considering, for example, a nonconducting medium (J = 0):