Plane electromagnetic wave and metallic waveguide

[patjk]

Explain why a plane electromagnetic wave cannot propagate through a metallic waveguide.

I've tried to come up with an answer, but I haven't been able to. I thought metallic waveguides were good since they reflected the propagating wave very well, allowing the wave to move without much loss in power. Am I wrong? Why can't an EM wave propagate through a metallic waveguide?

Many thanks!

 

[gabbagabbahey]

The keyword is plane

 

[patjk]

I understand a plane wave doesn't bounce off the sides of the waveguide. But can't it still propagate down a metallic waveguide, nonetheless?

Cheers!

 

[patjk]

In addition to the question above, what significance would an antenna traveling across water have on the wave? would the water absorb some of the wave instead of reflecting it, causing the signal to weaken?

Cheers!