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Old May 21st 04, 10:36 AM
Reg Edwards
 
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In ether case adding that much wire (15,840 feet) for so little gain
sure doesn't seem worthwhile.

73
Danny, K6MHE

========================

Danny, I quite agree.

The current-carrying cross-sectional area of the Earth is enormous at
distances from the antenna base of 1/4-wavelength and greater. Regardless
even of very poor soil resistivity, loss in the soil is sensibly zero.

Furthermore, propagation velocity in the soil is MUCH less than the free
space velocity and I am of the opinion that computer models give a very
distorted picture of what actually happens.

At distances of the order of 1/8 free-space wavelength practically all of
the current flows in the soil. Shallow-buried radials might just as well not
be there. The copper is better used to increase the number of short
radials.

But an increase in the number of short radials is a waste of copper anyway
when the number of radials is already very large.

What B,L&E were doing with 120 radials at MF in 1937 is hardly relevant. I
understand they forgot to determine ground conductivity - an indication they
didn't fully appreciate what they were about. As they were the first in the
field to make such measurements this omission is understandable. But at HF,
soil characteristics are considerably different - factors which computer
model users do not feed into their models.

Computerised antenna model users are inclined to suffer from delusions of
accuracy - drowning, unaware, in a sea of uncertainties.

But there's no real harm done! ;o)
----
Reg.




 
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