Simulation will tell the tale but in the mean time we have two things
caused by the up-and-over that we can mull over:
1) There is cancellation of the magnetic fields by the up-and-over wires
thereby minimizing any additional inductance to the normal radial return
current.
2) current is induced in the vertical wires by the antenna magnetic field.
This induced current is opposite to the normal radial return current.
Dave WX7G
On Aug 10, 2012 10:26 AM, "Bill Wichers" <billw@waveform.net> wrote:
> I would expect an "up and over" to clear the wall would result in a
> choke-like effect on the radial and would, at best, reduce the radial's
> effectiveness.
>
> It should be easy to just drill some small (maybe 1/4"?) holes through
> the wall in a few places to pass the radials through. With a decent
> hammer drill and a carbide bit a small hole like that is pretty quick
> and easy to complete -- even in concrete or stone. Then just use a piece
> of coathanger wire as a wire fishing tool to run the radials through the
> hole.
>
> I use a wire pulling tool called a "creep-zit" to pull radials under
> fallen trees and logs in the woods. It works great. I basically just
> take one of the 6 foot long fiberglass rods (each of which is a little
> over 1/8" diameter), tape the radial to one end, and then I can push it
> under fallen debris easily. With a little practice you can even get
> around hidden obstructions in the ground this way.
>
> -Bill
>
>
> > I shunt feed my tower for topband. I use variable vacuum caps and a
> vacuum
> > relay at the base to switch between the low end and the high end of
> the
> > band. It seems to work okay. I have 100' buried radials spaced 10' at
> the
> > ends from o degrees going clockwise through about 220 degrees. I have
> a 4'
> > high stone wall that runs about 20/200 degrees that is about 35' at
> its
> > closest point to the tower. So the radials are progressively shorter
> on
> > the
> > West side of the tower.
> >
> >
> >
> > I am making an assumption that going up over the wall will distort any
> > benefits of extending the radials on the West side? Is that a true
> > assumption.
> >
> > I can't really have the radials go from the tower base up at an angle
> to
> > clear the stone wall and continue on. If I am to extend them the
> radials
> > would have to go on the ground to the wall then up and over and back
> down
> > to
> > the ground.
> >
> >
> >
> > 73,
> >
> > N2TK, Tony
> >
> > _______________________________________________
> > UR RST IS ... ... ..9 QSB QSB - hw? BK
> _______________________________________________
> UR RST IS ... ... ..9 QSB QSB - hw? BK
>
_______________________________________________
UR RST IS ... ... ..9 QSB QSB - hw? BK
|