Topband: shunt fed tower - question?

[Tom Rauch]

> Just read the post by W4ZV that he plans to use a 2
conductor shunt feed to
> increase B/W.  I wonder if two conductors will obtain the
"shielded from the
> outside world" effect refered to above? Does it make any
difference?

It makes no difference at all.

A basic principle of RF is that common mode current always
moves to the outside area of a conductor. The effect causing
this is the same effect causing skin depth. There is no way
around it, and the differential mode currents can't cause
radiation. This is why coaxial cables only radiate from the
outside of the shield, it's why a small shielded loop has
ALL the radiation currents flowing on the outside of the
shield. The shield radiates and receives, not the wire
inside the shield. A skirted antenna behaves the same way.

We sure waste a lot of time where we could be progressing
forward revisiting things that were well established 100
years ago. The unfortunate thing is I doubt those
measurements will stop the myths from resurfacing. Old those
old incorrect theories that appear in books like Orr's
handbook  will be out there for many many years.

73 Tom