I've done extensive experimentation with radials on vertical antennas on
160 meters during the past 18 years.
Back in 2001 a MF broadcast engineer friend of mine using professional
broadcast measuring equipment, took near field measurements of the electric
field in V/m RMS. The antenna was a 1/4 wave inverted L with a 64 foot
vertical section and (1/8 wave) 64 foot long radials laying on the ground
I found the following.
There was little measurable difference between 0 and 4 radials, a small
measurable difference between 4 and 8 radials, a medium measurable
difference between 8-16 radials, a large measurable difference between 16
and 32 radials, a small measurable difference between 32 and 64 and no
discernable measurable difference between 64 and 120 radials.
We then conducted another experiment using conventional (1/4 wave) 128 foot
found the data to be exactly the same as the 1/8 wave radials. To me this
the theory that the radials need not be any longer than the vertical section
I have never had the opportunity to do the experiment with a full 1/4 wave
This statement will be controversial. Using a voltage fed electrical 1/2
wave tee antenna with a 64 foot vertical section and three 200 foot long
top hat wires, in the near field we measured only a very small difference
1 radial and 64 1/8 wave radials. We measured no difference between 1 radial
and 64 1/4 wave radials.
The ground conductivity was pretty good at the location of the experiment.
a typical Florida hammock swamp that had been filled in but always had black
soil and a high water table. The conductivity was approximately .03 S/M with
constant of approximately 20.
I've always presumed that the results might be different over ground with
- -... ...- -,
Thomas F. Giella, KN4LF
Lakeland, FL, USA
KN4LF SWL & Amateur Radio Autobiography: http://www.kn4lf.com
New Scientific Evidence for the Existence of God:
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