[TowerTalk] signals on inside of a pipe.. RE: TT SHUTDOWN (was: 4 awg copper wire and Amp locks)

[Jim Lux]

At 12:18 PM 7/12/2006, Gary Schafer wrote:

>If the shield of a coax cable carries a lightning strike about half of the
>energy gets transferred to the center conductor of the cable and propagates
>down the cable just like a radio signal would. This includes the propagation
>delay caused by the velocity factor of the coax.
>
>The energy gets inside the coax from the low frequency and DC energy carried
>by the shield. This penetrates, as the skin effect falls apart, where the
>skin effect would normally keep it on the outside. The field that is now on
>the inside of the cable gets induced onto the center conductor.
>The effect is called transfer impedance.
>
>However if there is no center conductor in the pipe the high frequencies
>will not be able to propagate down the inside and will die out.


yes, but how fast does it die out?  It's not going to propagate in a 
waveguide mode very far, but does it propagate another way?