[Elecraft] RF on pipes

[Geoffrey Mackenzie-Kennedy]

Point taken Ian, grey cells in reverse gear here :-)

73,
Geoff
GM4ESD


On July 09, 2011 at 19:17Z, Ian White GM3SEK wrote:

> No - HF fields cannot propagate inside an open tube because it behaves 
> as like a 'waveguide beyond cutoff'. Any HF EM field injected into the 
> open end will only penetrate a very short distance inside before it 
> decays away.
> 
> Coax is different because it contains *two* conductors: the inner skin 
> of the tube and the outer skin of the centre conductor. The internal 
> field is created between these two conductors and is thus able to 
> propagate down the line.
> 
> So the answer to the OP's question is that tubing will only give him the 
> benefit of the larger outside skin.