Since electromagnetic energy cannot pass through a perfect conductor a plane wave incident on a conductor has all of its energy reflected.

As the electric field at the surface of the conductor must be equal to zero at all times in order to obey Maxwell's equations, the reflected wave must be equal in magnitude to the incident wave. For the case when E-field polarization is in the plane of incidence, the boundary conditions require that

$$\theta_i=\theta_r-----(1)$$

and

$$E_{i}=E_{r} \quad \text {(E-field in plane of incidence)}-----(2)$$

Similarly, for the case when the E-field is horizontally polarized, the boundary conditions require that

$$\theta_i=\theta_r-----(3)$$

and

$$E_{i}=-E_{r} \quad \text {(E-field normal to plane of incidence)}-----(4)$$

Referring to Equations 1 to 4 we see that for a perfect conductor, $\Gamma_{ \|}=1,$ and $\Gamma_{\perp}=-1,$ regardless of incident angle.