On N6LF web page you can find the QEX series on ground mounted radials.
And there is a ton of discussion of this topic on the reflector as it
seems to come up often (may be mixing it with the towertalk reflector).
73/jeff/ac0c
alpha-charlie-zero-charlie
www.ac0c.com
On 1/1/21 11:28 PM, List Mail wrote:
Yes, the antenna modelling is helpful, but by no means definitive.
Several years ago I put up a top loaded vertical over a very limited
buried radial field, 16 x 20 m. It worked, but nothing exciting. It
was very hard work burying wire in very hard ground.
I then put up an elevated radial system, starting with a pair, tuning
them like a dipole. Same with the second pair. After four, the tuning
didn't seem at all sensitive. I ended up with 7 x 1/4 wave radials,
plus a shorter one where the property boundary was too close. The
radials were about 2.5 m high, just high enough to not touch with my
outstretched hand. That seemed to work quite ok, compared with a full
wavelength doublet antenna up 20 m.
I then moved and set up the top loaded now trapped vertical over
elevated 4 x 1/4 wave radials for 160 and 4 x 1/4 radials for 80 m. I
quickly tired of repairing fallen radials where a horse had rubbed on
a post or where I caught the wire on the tractor exhaust pipe! Again,
it worked me a decent amount of DX. And I mean "DX" as nearly
everything is a very long way from VK3.
Last year, I did the work of burying 60 x 33 m radials, clearing away
the mess of overhead wires. Does that work any better than the
elevated radials? I cannot know, as there was no means of comparative
testing. But, it's a whole lot tidier with the wires under the ground
than overhead.
My conclusion is that elevated radials do work quite decently, and
they are probably a little less work than burying a decent radial
field. Wires on the ground were never an option, with livestock in the
paddock. My suggestion, and the references too, is to put the elevated
radials up as high as practicable (higher than I had them). This
allows easy access to vehicles to drive under them, without tearing
something down.
The aim of the radials is to reduce the effect of ground return path
losses, and even with 8 radials, I could drive under them, listening
to Radio National on 621 kHz, and the signal would be significantly
attenuated. All of the above observations were over fairly poor
ground, decomposed granite, with granite rocks floating. There is
water underlying, however.
73, Luke VK3HJ
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