"Richard Clark" wrote
"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.

Hi OM,
Both Reg and you would do well to obtain and read a copy....
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. ... (etc)

I have the paper, and have read it carefully, many times. The paper gives
equations and graphs for current in the radial wires for a perfectly
conducting Earth, and for Earth conductivities of 20 x 10^-15 e.m.u. and 100
x 10^-15 e.m.u. Later, in the experimental data, they report measurements
of the currents for various radial configurations during their measurement
sequences. But as I wrote, nowhere do they specifically report the actual
ground conductivity for the antenna site, or along the 0.3 mile propagation
path of the test. If you can find that anywhere in that paper, I will
promptly retract my statement, and apologize.

Figure 30 in the paper shows that the ground system comprised of 113 radials
of 0.412 lambda each resulted in a measured field strength that was about
0.18 dB below the theoretical value for it from a 90 degree radiator against
a zero-ohm connection to a perfect Earth. I expect most of us would be
quite happy if our measured data agreed that closely with its theoretical
value. In any case it does show that the actual value of the ground
conductivities for the test site and path had a trivial bearing on the test
results, e.g., it was unimportant.

In fact the efficiency of AM broadcast vertical radiators per the FCC
definition always is based on a perfect ground plane, and two ohms or less
of DC resistance in the transmitter connection to it (via the radial ground
system). Only then is distant field strength determined, using the radiator
efficiency value and applied RF power along with the appropriate FCC
propagation curve for the frequency and Earth conductivity for the path.

RF

On Tue, 9 Aug 2005 15:32:22 -0500, "Richard Fry"
wrote:

But as I wrote, nowhere do they specifically report the actual
ground conductivity for the antenna site, or along the 0.3 mile propagation
path of the test. If you can find that anywhere in that paper, I will
promptly retract my statement, and apologize.

Hi OM,

As stated previously:

"Fig. 6 shows the actual current in the earth for the same conditions"

I hope the word "actual" is not subject to recourse to the IEEE
dictionary for clarification.

The "same conditions" are explicitly specified with conductivity.

One has to trust that engineers did not ask the farmer's wife to make
this determination for them in her kitchen. The imputation of
distrust would seem to serve another agenda.

Figures 7, 8, 9, and 10 also are all quite explicit.

The paper offers enough data to render your objections as tedious as
my work disproving "total cancellation" - the difference being I did
the work instead of simply saying "'t'ain't so." ;-)

73's
Richard Clark, KB7QHC

"Richard Clark" wrote
"Richard Fry" wrote:
But as I wrote, nowhere do they specifically report the actual
ground conductivity for the antenna site, or along the 0.3 mile
propagation
path of the test. If you can find that anywhere in that paper, I will
promptly retract my statement, and apologize.
As stated previously:
"Fig. 6 shows the actual current in the earth for the same conditions"
The "same conditions" are explicitly specified with conductivity. etc
__________

Yes, BL&E reported on the currents in the radials and the total ground
currents during the test (as I already stated), but that is not the issue.
The issue is whether or not not they explicity reported the value of Earth
conductivity for the test site and propagation path--and they did not. Nor
was it important to the conclusions of the test.

RF

Richard Clark wrote:

Hi OM,

As stated previously:

"Fig. 6 shows the actual current in the earth for the same conditions"

I hope the word "actual" is not subject to recourse to the IEEE
dictionary for clarification.

I agree with Richard Fry. All the references to ground conductivity,
including Figure 6, are in Part II, the (erroneous) theoretical
treatment. As for the "actual", look back a page, to page 759, at the
bottom, where they say, "Thus from [equations] (8), (9), and (10),
together with Fig. 4 ["Calculated Values of Total Earth Current"], we
may obtain the actual current in the earth and the current in the
wires." So the "actual" current is calculated from three equations and a
graph of calculated current. Whatever they might have meant by "actual",
it doesn't mean that it was measured.

The "same conditions" are explicitly specified with conductivity.

One has to trust that engineers did not ask the farmer's wife to make
this determination for them in her kitchen. The imputation of
distrust would seem to serve another agenda.

Figures 7, 8, 9, and 10 also are all quite explicit.

They are also part of the theoretical treatment and don't represent
measured values. Measured values begin with Fig. 25.

. . .

Brown, Lewis, and Epstein did a good and careful job of measurement.
Please be careful not to confuse their not-so-good theoretical treatment
with their measurement results.

Roy Lewallen, W7EL

Reg Edwards wrote:

Until now I have not contributed to this discussion. Neither now and
very little in the past. So please leave me out of it.

I have produced one small program (I am surprised at the attention
drawn to it) which computes radiating efficiency of a short vertical
antenna based on a novel analysis of ground loss, ie., shallow buried
radial wires which behave as lossy transmission lines.

All I have to say is that the program gives the "right" answers.
Disprove it if you can.

Considering that Brown, Lewis, and Epstein's experimental work has held
as being valid for about 70 years now, it can be used as a test for
various attempts at calculating ground system losses. NEC-4 matches
their results quite well; your program produces results which are
dismally different. Anyone armed with both the BL&E paper and your
program can see for himself.

It is as accurate as the ground "constants" are known, that is about
plus or minus 30 percent. The answers are forthcoming within
milli-seconds. No need to go on a one month training course. And it's
free. What more do you want?

It's sure a lot easier to create an easy-to-use free program if the
results don't have to bear any resemblance to reality. But perhaps
you're right -- maybe people who use free software shouldn't expect the
author to be honest about the program's accuracy.

To prove it wrong you have to create a set up similar to that pruduced
by BL&E - only this time don't forget to measure ground coductivity
and permittivity!

Your program fails badly with any reasonable ground conductivity and
permittivity. NEC-4 does pretty well with reasonable assumptions for the
ground quality of a field in New Jersey in the wintertime.

From what Roy says, BL&E were hardly better than bungling amateurs of
their era.

Once again, you've crossed the line from your normal pomposity and
crankiness to an insult and lie.

The only reason their report is considered to be 'The
Bible' is because it was the only one ever produced and available at
the time.

Another untruth. It stands because their measurements took in quite a
number of conditions, and have been replicated.

They laid down so many radials it didn't matter what ground
conductivity was.

Those people who have read the paper know this to be untrue, also. They
made measurements with 2, 15, 30, 60, and 113 radials.

Isn't that kind of a record, Reg, three flatly untrue statements in a
single posting? You should record the name of that wine and save it for
those special occasions when you feel threatened by the possibility that
some Yanks might have done something useful 70 years ago. Hope your
favorite store has lots in stock. In vino veritas, indeed.

Roy Lewallen, W7EL

On Tue, 09 Aug 2005 15:07:21 -0700, Roy Lewallen
wrote:
Whatever they might have meant by "actual",
it doesn't mean that it was measured.
....
Brown, Lewis, and Epstein did a good and careful job of measurement.
Please be careful not to confuse their not-so-good theoretical treatment
with their measurement results.

If I compare this with

On Tue, 09 Aug 2005 15:25:37 -0700, Roy Lewallen
wrote:
Considering that Brown, Lewis, and Epstein's experimental work has held
as being valid for about 70 years now, it can be used as a test for
various attempts at calculating ground system losses. NEC-4 matches
their results quite well; your program produces results which are
dismally different. Anyone armed with both the BL&E paper and your
program can see for himself.
....
Your program fails badly with any reasonable ground conductivity and
permittivity. NEC-4 does pretty well with reasonable assumptions for the
ground quality of a field in New Jersey in the wintertime.

leads to amusing circularity which I will set aside.

One might well suppose that through fine parsing, "actual" is not, and
is code for "might be." All reasonably argued, but reason has been
replaced with the rhetoric of argument fighting for air.

The authors express that with their formulas (8), (9) and (10) that
results would be "accurate" which I presume parses here to "best
guess." I also note that what falls within the "theoretical"
discussion is couched with the variables set in the "measurement"
discussion. The paper, as would be expected, was written iteratively
and results were drawn back into the theory.

The theoretical discussion of radial counts does not proceed from a
natural 15, 30, 60, 113 progression - this is plainly ad hoc
determination. Nor does the theoretical discussion of antenna height
proceed naturally through 22, 44, 66, 88, and 99 degrees - again
arrived at by ad hoc methods. All such "theoretical" considerations
are the happenstance of what was available in the field. It is
overwhelmingly obvious that Figures 4 through 14 are derived from the
3MHz tests employing antenna sections of 20', 20', 20', 20', and 10'
which fall right on the curve at the 1.098 degrees per foot of section
used. The text clearly states this: "The antenna heights given here
were chosen to conform to later experimental heights." This admission
precedes the introduction of ground conductivity, and yet after all of
this ad hoc conscription from the field flows the presumption that the
ground conductivity is derived. To put it bluntly, the data and
system variables inhabit the theoretical discussion like a glove.

Like a political promise, the embraced vague genesis of ground
conductivity has been heralded for every purpose but what the authors
put it to.

73's
Richard Clark, KB7QHC

Whatever little BL&E may have contributed to the theoretical aspects,
it has always been disregarded by broadcasting engineers who always
did what they did last time - and laid 120 radials regardless of
economics.
----
Reg.

On Wed, 10 Aug 2005 00:54:35 +0000 (UTC), "Reg Edwards"
wrote:

and laid 120 radials regardless of economics.

Hi Reg,

For a million dollar station investment, I don't think the price for
shares in Anaconda have brought any significant attention to anyone.

Perhaps you are thinking of the relative price in 1906 when it cost 4
times as much against 5% of what we consume now. Well, maybe only 30
years ago when it cost more than 3 times as much as now. Or perhaps
only 10 years ago when it cost twice as much as now.

Odd, it seems the price of copper and the value of the Pound have been
tracking each other over that same period. Your complaint would be
better founded on us planting sterling radials.

73's
Richard Clark, KB7QHC

Richard Clark wrote:
On Tue, 09 Aug 2005 15:07:21 -0700, Roy Lewallen
wrote:

Whatever they might have meant by "actual",
it doesn't mean that it was measured.

...

Brown, Lewis, and Epstein did a good and careful job of measurement.
Please be careful not to confuse their not-so-good theoretical treatment
with their measurement results.


If I compare this with

On Tue, 09 Aug 2005 15:25:37 -0700, Roy Lewallen
wrote:

Considering that Brown, Lewis, and Epstein's experimental work has held
as being valid for about 70 years now, it can be used as a test for
various attempts at calculating ground system losses. NEC-4 matches
their results quite well; your program produces results which are
dismally different. Anyone armed with both the BL&E paper and your
program can see for himself.

...

Your program fails badly with any reasonable ground conductivity and
permittivity. NEC-4 does pretty well with reasonable assumptions for the
ground quality of a field in New Jersey in the wintertime.


leads to amusing circularity which I will set aside.

Sorry, as so often happens I missed your point entirely. If you're
interested in having me understand what "circularity" you mean, you'll
have to be more blunt and pedestrian so I'm able to understand it.


One might well suppose that through fine parsing, "actual" is not, and
is code for "might be." All reasonably argued, but reason has been
replaced with the rhetoric of argument fighting for air.

Again, I haven't a clue what you're talking about. Arguing semantics, I
suppose, in which I'm afraid I have no interest.

The authors express that with their formulas (8), (9) and (10) that
results would be "accurate" which I presume parses here to "best
guess." I also note that what falls within the "theoretical"
discussion is couched with the variables set in the "measurement"
discussion. The paper, as would be expected, was written iteratively
and results were drawn back into the theory.

I'm missing this one, too. If you're saying that those three graphs are
of measured data, I can present what I believe is a good argument
against that premise. But I can't tell if that's what you're saying or not.

The theoretical discussion of radial counts does not proceed from a
natural 15, 30, 60, 113 progression - this is plainly ad hoc
determination. Nor does the theoretical discussion of antenna height
proceed naturally through 22, 44, 66, 88, and 99 degrees - again
arrived at by ad hoc methods. All such "theoretical" considerations
are the happenstance of what was available in the field.

It wouldn't surprise me a bit if the theoretical work was written or
modified after the measurements were made, which I believe is what
you're saying. That doesn't alter the fact that the graphs of Part II
are from calculated rather than measured results.

It is
overwhelmingly obvious that Figures 4 through 14 are derived from the
3MHz tests employing antenna sections of 20', 20', 20', 20', and 10'
which fall right on the curve at the 1.098 degrees per foot of section
used.

I'm not sure what you mean by "derived from", but they sure aren't
graphs of measured data. For starters, some of those graphs are for 1
MHz, while according to the paper all measurements were made at 3. For
another thing, I'm sure they didn't have the ability to change the
ground conductivity; some of the graphs are for different ground
conductivities than others. Finally, compare Figures 7 and 8 with Figure
42. The latter is from measured results, as explained on p. 781. It's
quite different from the theoretical results for Figures 7 and 8.
Incidentally, the theoretical analysis, including Figures 7 and 8, seems
to assume infinite radial length, which is another difference between
the theoretical and measured conditions (besides ground conductivity
and, in some cases, frequency).

The text clearly states this: "The antenna heights given here
were chosen to conform to later experimental heights."

That's a very reasonable thing to do, when presenting both theoretical
and measured results. I believe you're drawing conclusions from it which
are well beyond its straightforward intent. (Perhaps this is due to your
English literature background? It certainly was one of the activities
overwhelmingly emphasized and encouraged in all English lit courses I
ever took.)

This admission
precedes the introduction of ground conductivity, and yet after all of
this ad hoc conscription from the field flows the presumption that the
ground conductivity is derived.

?

To put it bluntly, the data and
system variables inhabit the theoretical discussion like a glove.

Even that isn't blunt enough for me. Sorry. I did badly in English.

Like a political promise, the embraced vague genesis of ground
conductivity has been heralded for every purpose but what the authors
put it to.

If you say so. Whatever you said.

Roy Lewallen, W7EL

On Tue, 09 Aug 2005 18:43:19 -0700, Roy Lewallen
wrote:

Like a political promise, the embraced vague genesis of ground
conductivity has been heralded for every purpose but what the authors
put it to.

If you say so. Whatever you said.

Hi Roy,

It must have taken great effort of will to come to that conclusion.
Your achievement is noted as has all the groaning along the way.

73's
Richard Clark, KB7QHC