Topband: Fw: Re: Radials over a stone wall

[Tom W8JI]

> If a radial runs along the ground and then up over a wall, what difference
> would it make?

Good question.

The radial only goes up for 4 feet and back down for 4 feet.

That is exactly like adding a 4-foot shorted stub in series with the radial. 
All that worry about induced current in a 4-foot vertical section from the 
vertical is needless. What is added to the rising wire from the vertical's 
field is subtracted from the descending wire. If we are going to worry about 
the wire being driven by the antenna, we should really worry about a car 
parked near the antenna!

So it is just like adding a series 4 ft shorted stub of a certain 
characteristic impedance determined by the dielectric of the wall, wire 
diameter, and the spacing of the wires.

I think if it was my wall, I would run the wire up and over the 4-foot wall 
and not spend so much time worrying about the 2.7 electrical degree long 
shorted stub, or ~30 ohms inductive reactance, a thin wire stub added.

If the 30 ohms inductive reactance (which in itself does not add loss) 
really kept me awake, I'd go over the wall with copper flashing, or three 
small conductors fanned apart to several inches spacing at the wall top, and 
then it would only add about 10 ohms of inductance.  :-) One way or another 
I'd get something over that wall.