[Top] [All Lists]

Re: [TowerTalk] question on where to run coax

To: Dick Hanson <>
Subject: Re: [TowerTalk] question on where to run coax
From: jimlux <>
Date: Mon, 16 Aug 2010 06:37:47 -0700
List-post: <">>
Dick Hanson wrote:
> Howdy....
> I have several towers here, each with multiple ants on them.
> Is there a consensus on whether to run the coax taped to the inside of the
> tower legs or to the outside.
> Obviously easier to do the outside, but wondering about lightning?

I doubt it makes much difference, unless you were very careful about how 
you routed the coax in the center of the tower.

If lightning actually hits the tower, it might well have hit the 
antenna, and then the coax is actually in the path. Or, if the stroke 
current is flowing in the tower, it will induces a current in the shield 
of the coax, whether the coax is inside the tower or outside.  In 
theory, if the tower were a nice perfect tube, then the lightning 
current would flow only on the outside of the tube (just like coaxial 
cable).. but towers are not solid symmetrical tubes.  The current is NOT 
going to magically distribute evenly, so some is going to travel on the 
inside of the tower, and be unevenly distributed, so the fields don't 
cancel nicely at your coax carefully suspended at the geometric center.

Same sort of argument if you're talking about a nearby stroke inducing a 
current in the tower.

Ground the shield of the coax at the base of the tower, accept that you 
might have to replace a length of coax some day, be happy.

TowerTalk mailing list

<Prev in Thread] Current Thread [Next in Thread>