Topband: Tuning elevated radials

[Tom Rauch]

Are you saying that a simple elevated radial system is 5 or
6 dB down from the classic 120 buried radials?  This seems
to run in conflict with things I've read elsewhere.>

In all the actual real-world FS measurements I've made and
seen made by other people there is 2-8b dB difference
between 60 1/4 wl radials and a small elevated system that
is close to earth. Results vary with soil types, since very
poor conductivity and very good conductivity should have the
lowest loss.

120 radials are unnecessary, that number just comes from FCC
requirements. Not from FS data. The FCC simply believes
twice the optimum means it is safe if something goes wrong.
60 1/4 wl radials are enough to get well out on the flat
part of the efficiency curve.

In models using older engines like NEC-2, there isn't a
difference shown between small resonant systems at low
height and conventional systems. But then almost anyone
knows NEC2 did a poor job of estimating earth effects. A low
dipole shows 5 dB or so more strength than it has in real
world measurements using NEC-2.

Long before Brown, Lewis, and Epstein made the classic study
"ground systems as a factor in efficiency" for RCA virtually
all systems were elevated resonant counterpoises. The RCA
study had the overwhelming result of making everyone switch
from counterpoises to conventional radial systems. Nearly
3/4 of a century later, based on a computer program that
treats the earth as an unverified uniform loss media with no
A-B field trials, everyone was ready to switch back.

73 Tom