"Jack Painter" wrote in message
news:7exxc.5734$5B2.1970@lakeread04...

Hi Gary, the difference that is relevant, I believe, is a waveguide for
microwave broadcast through the inside space of the guide, and there is
minmal current intentionally allowed on the waveguide.

Wrong Jack. Electromagnetic waves in a waveguide are only possible when
voltages and currents are present. The maximum voltage is between the two
larger sides while currents flow from one side to the other. The entire
field is contained inside the waveguide and therefore the inside surface
must have a low resistance and is silver plated to achieve this. You can
read this in any textbook on microwave transmission.

As I did explain,
skin effect must be avoided in microwave and it is due to the frequencies,
however it may be exploited in HF conductors which can eliminate wasted
center-core weight and cost. This is because of the drastically different
behavior of microwave from HF. And velocities inside a waveguide are much
faster than HF on a conductor. The attenuator you are describing allows
skin effect (it cannot avoid it either) but the true waveguide avoids it,
with the microwave reflecting off the walls of the guide.

Why do you think a microwave reflects on the wall of the waveguide? Because
current flows on the inside wall, which has to have the lowest resistance
possible. It is all skin effect what makes a waveguide tick!

Meindert