"Jack Painter" wrote in message
news:r_yxc.3506$K45.1736@fed1read02...

Hi Meindert, how is that skin effect when, as you said, the currents must
flow from one side to the other? Skin effect would hold currents _on_ the
surface, slow them down, and reduce the reflection that is required for
propagation through the guide.

With "one side to the other" I meant from the top inside to the bottom
inside, if you lay the waveguide flat on the table. The maximum voltage
inside the waveguide exists between top and bottom of the inside.

Of course, the current never travels from the inside to the outside of the
waveguide.

Below the minimum frequency of a waveguide, no energy can be transported
inside the waveguide and thus no currents will flow at the inside.

Meindert