An alternative way to characterize attenuation is in terms of skin depth δs, which is defined as the distance at which the magnitude of the electric and magnetic fields is reduced by a facto...An alternative way to characterize attenuation is in terms of skin depth δs, which is defined as the distance at which the magnitude of the electric and magnetic fields is reduced by a factor of 1/e. Since power is proportional to the square of the field magnitude, δs may also be interpreted as the distance at which the power in the wave is reduced by a factor of (1/e)2≅0.135.
