Topband: Number of radials - elevated vs grounded

[John B. Mitchell]

I too have been experimenting with elevated radials at the ridgetop tower
here at K4IQ.  The ground has too many rocks and old tree stumps and root
systems from being cleared five years ago to use in-ground radials, anyway.
Since working Milt years ago and seeing his plus 20 signal barefoot into VA,
I've been intrigued by GP antennas on Top Band.  I've had more than a few
collegial debates with proponents of traditional ground radial systems.
Here is the current state of my theoretical speculations, black magic,
whatever you want to call it for those, like me, afflicted with poor or
intractable ground.
A GP vertical, high enough to de-couple most serious ground losses, will
probably equal a broadcast installation over the same lossy ground. It all
comes down to how high can I get the feedpoint.  I presently have a 100 ft.
tower with a short extension.  I am using a longer than 1/4 wave,
series-fed, radiator (about 165 ft), fed a few feet above the tower base,
through a heavy vacuum variable.  I constructed a radial ring, using
non-conductive mechanical support and a conductive #6 solid ring, to which
I've attached (at present) eleven elevated radials, all of the same length -
130 ft.  These run mostly in straight lines, except for two near the
property border that have to dogleg. The average height for most of these
radials (the gnd slopes somewhat away from the tower base) ranges from 8
feet to 20 feet above lossy ground.  I feed through a current balun.
Performance has been very good.  This antenna replaced an inverted vee at
100 ft.  It definitely seems to have an edge over the vee into Europe and
Hawaii, while losing maybe 3-5 db inside 250 miles.  It's at least as good
as the vee at intermediate distances.  (Note, the vee, over sloping
terrain - this is a ridge top - did much better than I expected on DX).
If I could get this tower up to 140 feet or so, here's what I would like to
try:  elevate the feed point to about 40 feet (higher would be even better);
construct cage-like radials like Milt uses and BALANCE them for the ground
conditions under each.  To get currents to cancel effectively, the GP
radials have to be balanced.  If one or two are taking all the current, the
pattern will be lop-sided, and may well be radiating a large portion up into
the near-zenith.  That's one reason I'm using so many radials now - to
equalize currents in as many azimuth directions as I can and give the
antenna a chance to work.
This is how I think present antenna is working:  a dozen or so elevated
radials, even located within 1/50 wl of lossy ground, still gives more
separation from that lossy ground than a few more radials lying on top of
the ground.  There is just no question in my mind that ANY height above
ground works better than having the GP in the ground.  (A dipole on the
ground doesn't work at all, raise it even a few feet and it works poorly,
but better.)
I hope to eventually evolve this antenna into a "true" GP antenna with
feedpoint elevated enough to reduce near field losses even more.  It works
pretty well for now, and is a practical way to get some lower angle
radiation than a dipole over terrain that just doesn't support in or on
ground systems.  I would be interested in hearing from others who have
experimented with resonant (more or less) GP radial systems at lower than
optimum feedpoint heights to learn what your results have been, especially
if such antennas replaced more extensive in-ground radial systems.

73
John K4IQ