Question

A right-handed circularly polarized (RHCP) electromagnetic wave is normally incident on a perfect electric conductor (PEC).

(a) Calculate the reflection coefficient.
(b) What’s the polarization of the reflected wave?

Answer 1

a] PEC boundary is one where the boundary has the Electric field zero [Electric field is always zero within a conductor]. This is similar to wave inside a tube where nodes are formed at the boundaries. So, the entire wave will be reflected and so the reflection coefficient here will be r = 1.

This can be verified by Fresnel's coefficient for reflection at normal incidence.

b] Since the boundary is E = 0, the reflected wave has inverse symmetry now (the crests become troughs and vice versa). So, the reflected wave will be Left-Circularly polarized.