NEC-LIST: Elevated Radials

I ran some parametric studies of monopoles on radial-wire ground
screens for a paper for the IEEE/APS Conference back in 1989. We
modeled screens with 4, 8, 16, 32, 64 and 128 radials, with the screen
above and below ground. We also modeled screens with and without a
ground stake under the antenna and at the ends of the radials.
Results included input impedance, "relative communication efficiency"
(power at a location on the ground relative to a reference antenna
with equal input power) and radiation efficiency obtained by
integrating power over the upper hemisphere.

The 4-wire screen above ground worked well if the radials were tuned
to the 1/4 wavelength resonance. However, the necessary length
depended somewhat on the height of the screen above ground. Mel
Weiner published some of these results in detail, but I do not have
the reference handy. A short summary was in Electronics Letters,
Vol. 29, No. 16, pp. 1550-1551, 30th July 1992.

These results were run with the NEC-GS program, which is a version of
NEC-3 specialized to the symmetry of a vertical monopole on a uniform
radial-wire screen. The ground treatment is the same as in NEC-4. I
can send copies of the viewgraphs from the APS presentation and other
plots if you send a mailing address.

Jerry Burke
LLNL
Received on Mon Jun 29 1998 - 09:14:07 EDT