As the EM field inside the perfect conductor is zero, the interface reflects the incident plane wave. and respectively represent the unit vector in the direction of propagation of the incident and reflected waves, is the angle of incidence and is the angle of reflection.

We find that

............................(6.69)

Since the incident wave is considered to be perpendicular to the plane of incidence, which for the present case happens to be xz plane, the electric field has only y-component.

Therefore,