The famous Brown et al. paper from 1937 on buried radials ground losses
-- a brief summary
Thanks to TB posts and R. Fry, I have been tempted down a path to
ancient paper analysis. The essential results from this have been given
before in terms of trades of height, number and lengths of radials.
Generally, not surprising, more and longer radials are better, with
various qualifications and considerations. A brief version of that most
relevant to hams is provided here in simple tabular form. Only two
vertical heights are considered, ~1/4 and ~1/8 wavelength (88 and 44
degrees) in comparison with the stated theoretical ideal of perfect
ground. Only results for radial lengths of 90 and 45 feet are given.
They are in dB loss (or gain if you don't like the minus sign) and might
be interpreted as the ground loss as measured by the signal at a mile
(1609 meters) away but near the ground (not sky wave). Since the data
translation from 0.3 miles to 1 mile assumed the perfect ground scaling,
the loss results are really those out to 1/3 mile all at 3 MHz.
dB loss using n 45' radials
n 88deg 44deg
2 -4.17 -6.30
15 -2.29 -3.57
30 -2.18 -3.43
60 -1.95 -3.16
113 -1.84 -3.03
Ideal 0.00 0.00
dB loss using n 90' radials
n 88deg 44deg
2 -4.17 -6.02
15 -1.25 -2.29
30 -1.05 -1.71
60 -0.85 -1.12
113 -0.65 -0.81
Ideal 0.00 0.00
So more is always better but how much you are willing to pay for the
next dB always
becomes the question. Impedances are in the paper.
Full painful story at http://n6mw.ehpes.com/BrownNotesFinal.pdf
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