Topband: Tuning elevated radials

[Tom Rauch]

 > What happens if the elavated radials have a ground
connection at the far
> end, prefereably slopng to earth?

It then becomes a conventional ground system with directly
coupled earth currents.

> I know this is against conventional "Marconi" wisdom but
even going so far
> as running a few "in between" ground down leads may
mitigate some of the
> unwanted horizontal radiation from the elevated radials.

If you want to read one brief summary of a multiple tuned
ground system that was changed to a conventional system you
can find it in section 19.4  of Jasik's "Antenna Engineering
Handbook".

Much of VLF antenna and ground design is applicable to MF
amateur systems used in crowded locations. VLF and urban
amateur systems are both "crowded" or "space limited". The
tricks that are tried at VLF to improve small grounding
systems and vertical antennas for greater efficiency often
find their way into amateur service.

While I'm not disputing the fact some of these trick systems
make people happy, the fact remains every time they are
compared in a direct test against a conventional system
occupying the same physical area they loose.

As for resonating a radial or counterpoise system at the
feedpoint, the hard fact is it makes no difference at all if
the radial loading coil or radial resonating circuit is in
series with antenna side of the feedpoint or the ground
side. I'm sure anyone who is familiar with two terminal
networks and electrical rules would agree with this. The
feedline is the two-terminal source, and a compensating
reactance placed at or near the terminals can move from one
side to the other with no change in system behavior except
for an unwanted path like a third connection caused by a
ground rod or common mode shield currents. We do need to
minimize current flowing through any conductor to lossy
earth that might shunt current away from the small
counterpoise.

This is why any vertical with a marginal ground should have
a choke type "balun" or isolator at the feedpoint. Once the
feed system is properly isolated from earth, you no longer
have to worry about "resonating" the short radials. When the
antenna feedpoint is non-reactive the radials are tuned,
because the system is in complete resonance.

MFJ artificial grounds and copies of them are just band-aids
that move voltages around at the feedpoint. They don't
reduce ground resistance, although they sometimes can make
up for the lack of an isolating device like a current balun
at the feedpoint of antennas that are in the "neither-world"
between perfectly balanced and perfectly unbalanced. I had a
lot of time to test and think about this. I had a difficult
time finding anything spectacular to say when I rewrote the
manuals for a company selling artificial ground tuners.

73 Tom