On Tue, 9 Aug 2005 08:03:53 -0500, "Richard Fry"
wrote:
Nowhere in Brown, Lewis and Epstein's IRE paper titled "Ground Systems as a
Factor in Antenna Efficiency" is there ANY documentation of the actual
ground conductivity that was measured, or even calculated for the antenna
site and/or the propagation path used. It was unimportant for the construct
and relevancy of the tests and conclusions which the paper reported.

This is the paper I was referring to in my previous posts.

Hi OM,

Both Reg and you would do well to obtain and read a copy.

On page 757 is introduced the necessary discussion of:
Is = Iw + Ie
"The we will denote the total earth current flowing radially inward
.... as Is, ... where Iw is the component flowing in the wires, and Ie
is the part which actually flows in the earth.

The discussion of earth conductivity (quite specifically named as
such) within the paper spans pages 757, 758, 759, 760, with numerous
citations and graphings against specific conductivity values applied
to related figures in page 761, 762, 763, and 764.

On page 758:
"The actual earth current and the current flowing in the radial wires
are given by..." introducing formula (8).
Followed on page 759 with:
"while the current actually flowing in the earth is...." introducing
formula (10).
"Thus from (8), (9), and (10), together with Fig. 4. we may obtain the
actual current in the earth...."

As for explicit conductivity:
"Fig. 5 shows the current in the wires for the following conditions
.... 0.2X10^-4 mhos per cm cube"
"Fig. 6 shows the actual current in the earth for the same
conditions."

"shown for the following conditions..." and four specifications of
conductivity follow.

Now, specifically to a comment I offered as to the importance of
noting conductivity:
"When the earth is of good conductivity, the current leaves the wires
and enters the earth closer to the antenna than does when the earth is
a poor conductor."

There is also a formulation for Fig. 17 (page 766) that is introduced
as "The current is flowing toward the antenna through a ring of earth
of radius..." which computes the power lost to ground for a known
conductivity (with examples abounding).

In this short span of 8 pages dedicated to earth conductivity there at
least 12 graphs and charts all quite distinctly displaying the
variation of measured results as a function of different specified
ground conductivities antennas and ground system combinations.

The authors were quite aware of the ground beneath their feet and duly
reported its contributions in the standard engineering fashion of
displaying first principles.

73's
Richard Clark, KB7QHC