The numerical value of the ratio of electric field intensity E and magnetic field intensity H is

The intrinsic impedance of the wave is defined as the ratio of the electric field and the magnetic field phasor (complex amplitude), i.e.

\(η =\frac{E}{H}=\frac{j\omega \mu }{\gamma }\)

For free-space, the intrinsic impedance is a real quantity, i.e.

η  = η0 = 120π

η ≈ 377 Ω 

Notes:

A uniform plane wave has the following properties:

• The electric and magnetic fields are perpendicular to each other which are also perpendicular to the direction of propagation.
• They are also called as (Transverse electromagnetic wave) TEM waves.
• The ratio \(\frac{{\left| E \right|}}{{\left| H \right|}}\) for the wave is equal to the intrinsic impedance of the medium, η.