On Fri, 21 Jul 2006 23:04:54 +0100, "Reg Edwards"
wrote:


"Walter Maxwell" wrote
The graphs reporting BLE's measurements are pretty conclusive. In
addition, the
BLE paper is the basis on which the FCC set the requirements for the
ground
systems on all AM BC stations since 1939

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

Walt, where've you been lately?

I have no doubt that BLE measurements are good and valid at LF and
below. But to extrapolate conclusions up to HF, where amateurs reside,
and where funny things happen to radials, is somewhat dangerous.

I understand BLE forgot to measure ground resistivity and permittivity
of the site. Perhaps because they thought it didn't matter very much.
But such things certainly matter above about 3.5 MHz. At HF radials
behave very differently from behaviour at LF if only because the
ground 'constants' have changed from their DC and LF values (which are
the values usually inserted in HF computer programs.)
----
Reg.

Hi Reg,

I'll admit to being away from rraa for quite a while. A good bit of the time
away was while finishing the writings for Reflections 3, which includes several
new chapters, some of which archive a portion of my escapades in designing
antennas for various spacecraft, including those that flew on the World's first
weather satellite, TIROS 1. I was fortunate in being at the right place at the
right time when the space age began. Those were the years I spent with Jess
Epstein, the 'E' of the BLE team. Some of the additional material that went into
Reflections 3 is available on my web page at www.w2du.com. I think you might
find Chapters 19A and 21A of interest.

From eavesdropping on the banter between you and Richard C it's easy to see that
your winery has kept your mental physique it top shape. I hope that your
physical physique continues at least in its present condition.

Getting now to BLE, I agree with you concerning the changes in ground
characteristics at HF compared with MF and LF. I don't know if you have a copy
of BLE, but you should know that the BLE experiments were performed at 3 MHz.
Please let me know if you have BLE, because I'd like to email you a copy if you
don't. It will demonstrate the hundreds of measurements taken meticulously to
arrive at the conclusions reported in their paper of 1937.

Of the many results of various combinations of radial lengths and numbers of
radials, the one that that stands out in my mind is the combination of the
longest radial, 0.412 lambda, with the maximum number or radials, 113. This
combination achieved near-perfect ground, yielding a field strength of 192 mv/m,
as compared to the theoretical maximum of 196 mv/m, achieved with perfect
ground. The reference for these numbers is 1000 watts delivered to the antenna
and measured at 1 mile. Notice that the difference between the ideal and actual
field strengths is only 2 percent.

Reg, concerning the difference in ground characteristics with frequencies above
3.5 MHz, please consider this. When the radials are long enough, and enough of
them spaced sufficiently close, the effect is that of nearly perfect ground,
regardless of the actual ground characteristics beneath the radials. Let's
consider a comparison. First, few radials widely spaced. Displacement currents
reach the ground everywhere surrounding the vertical radiator. Currents entering
the ground between the radials diffract toward the nearest radial of higher
conductivity. During its travel toward the radial it naturally encounters the
resistance of the ground. However, with many radials more closely spaced,
currents now entering the ground have a shorter resistance path in reaching the
nearest radial, approaching a negligible value.

My point is that when there is a sufficient number of radials of sufficient
length to approach a nearly-perfect ground, the ground characteristics beneath
the radials are irrelevant within the area they cover in determining the
terminal impedance and efficiency of the radiator. Therefore, the different gr
ound characteristics that prevail as the frequency increases above 3.5 MHz are
also irrelevant. This is not to say that the ground characteristics away from
the immediate area are not important.

You might get a chuckle concerning the number of radials being 113. The original
plan was to plow in 100 radials. When the grunts Jess Epstein and Bob Lewis had
plowed in the intended 100 there was wire left over on the spool. They asked
Brown what they should do with the remaining wire, he said, "Plow it in." The
remainder of the wire allowed just 13 more radials to be plowed in.

On a personal note, I engineered and built WCEN in Mt. Pleasant, Michigan, 500 w
on 1150 Kc (it was 'Kc' then), with a 300' Blau-Knox tower. I plowed in 120
radials. My Dad manufactured the plow, which I rode, while he drove the tractor.

Hope this keeps ya busy fer a while,

Walt, W2DU

On Sat, 22 Jul 2006 18:04:52 -0400, Walter Maxwell
wrote:

[snip]

Getting now to BLE, I agree with you concerning the changes in ground
characteristics at HF compared with MF and LF. I don't know if you have a copy
of BLE, but you should know that the BLE experiments were performed at 3 MHz.
Please let me know if you have BLE, because I'd like to email you a copy if you
don't. It will demonstrate the hundreds of measurements taken meticulously to
arrive at the conclusions reported in their paper of 1937.


Hi Walter, nice to see you back.

For Reg, or anyone else for that matter, the BLE paper is available at
http://k6mhe.com/BLE.html

73,

Danny, K6MHE

"Walter Maxwell" wrote
The graphs reporting BLE's measurements are pretty conclusive. In
addition, the
BLE paper is the basis on which the FCC set the requirements for
the
ground
systems on all AM BC stations since 1939

==========================================
My point is that when there is a sufficient number of radials of
sufficient
length to approach a nearly-perfect ground, the ground
characteristics beneath
the radials are irrelevant within the area they cover in determining
the
terminal impedance and efficiency of the radiator. Therefore, the
different gr
ound characteristics that prevail as the frequency increases above
3.5 MHz are
also irrelevant.
Walt, W2DU
============================================

Dear Walt,

At risk of upsetting a great number of patriotic USA citizens, all BLE
hero-worshippers, I admit to having speed-read BLE's lengthy paper
some years back. Their conclusion, that with a sufficiant number and
length of radials the ground characteristics are irrelevant, is so
glaringly apparent they could have stayed in their offices and saved a
great deal of expense and copper wire. I am reminded of John Cleese's
remark "They must have had first-class honors degrees in stating the
bleeding obvious".

Because BL&E omitted to measure ground conductivity and permittivity
on the site their conclusion amounted to making a virtue out of a vice
and Marzipan the Magician's magic number of 120 came into existence.
Their sponsors should have made them go back to finish the job.

In the absence of any other information at the time, the fact of
irrelevance was of interest to LF and MF broadcasters with money to
burn, but it was, and still is, of no use to radio amateurs, confined
to the HF bands with limited purses, small back yards and XYL's to
keep happy.

My small program Radial_3 has been singled out and I have been accused
of disagreeing in a disruptive, almost criminal manner with BL&E's
conclusions. This is patently untrue! The program has nothing to do
with BL&E except that it deals with a similar subject in terms
appropriate to amateurs and draws its own independent conclusions.

Your absence caused a little worry. Glad to hear you were only
working.
----
Reg.

"Richard Fry" wrote
N. B. for/to REG EDWARDS (G4FQP): I hope that you will be
motivated to
follow through on one or the other of these offers, and that you
will post a
comparison of the results of your ready-to-run, "radial_3" DOS
program as
compared to the BL&E datum, for equivalent conditions.

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

What equivalent conditions? Where can they be found? What was the
ground resistivity and permittivity on BL&E's site?

I am not motivated to do anything except reply to your remarks. You
are making a song and dance about it.

If anybody wishes to confirm or deny the usefulness of program
Radial_3 then all they have to do is do what I have done and bury a
few ( not 120 ) wires in their back yard and get on the HF bands.

Proof of the pudding lies in the eating!
----
Reg.

Hi Walt
Reading the words "plow it in" made me chuckle.
I always had the same attitude building AM broadcast antennas.
If there was wire left over, I'd "plow it in".
73
H.
NQ5H

"Walter Maxwell" wrote in message
...
On Fri, 21 Jul 2006 23:04:54 +0100, "Reg Edwards"

wrote:


"Walter Maxwell" wrote
The graphs reporting BLE's measurements are pretty conclusive. In
addition, the
BLE paper is the basis on which the FCC set the requirements for the
ground
systems on all AM BC stations since 1939

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

Walt, where've you been lately?

I have no doubt that BLE measurements are good and valid at LF and
below. But to extrapolate conclusions up to HF, where amateurs reside,
and where funny things happen to radials, is somewhat dangerous.

I understand BLE forgot to measure ground resistivity and permittivity
of the site. Perhaps because they thought it didn't matter very much.
But such things certainly matter above about 3.5 MHz. At HF radials
behave very differently from behaviour at LF if only because the
ground 'constants' have changed from their DC and LF values (which are
the values usually inserted in HF computer programs.)
----
Reg.

Hi Reg,

I'll admit to being away from rraa for quite a while. A good bit of the
time
away was while finishing the writings for Reflections 3, which includes
several
new chapters, some of which archive a portion of my escapades in designing
antennas for various spacecraft, including those that flew on the World's
first
weather satellite, TIROS 1. I was fortunate in being at the right place at
the
right time when the space age began. Those were the years I spent with
Jess
Epstein, the 'E' of the BLE team. Some of the additional material that
went into
Reflections 3 is available on my web page at www.w2du.com. I think you
might
find Chapters 19A and 21A of interest.

From eavesdropping on the banter between you and Richard C it's easy to
see that
your winery has kept your mental physique it top shape. I hope that your
physical physique continues at least in its present condition.

Getting now to BLE, I agree with you concerning the changes in ground
characteristics at HF compared with MF and LF. I don't know if you have a
copy
of BLE, but you should know that the BLE experiments were performed at 3
MHz.
Please let me know if you have BLE, because I'd like to email you a copy
if you
don't. It will demonstrate the hundreds of measurements taken meticulously
to
arrive at the conclusions reported in their paper of 1937.

Of the many results of various combinations of radial lengths and numbers
of
radials, the one that that stands out in my mind is the combination of the
longest radial, 0.412 lambda, with the maximum number or radials, 113.
This
combination achieved near-perfect ground, yielding a field strength of 192
mv/m,
as compared to the theoretical maximum of 196 mv/m, achieved with perfect
ground. The reference for these numbers is 1000 watts delivered to the
antenna
and measured at 1 mile. Notice that the difference between the ideal and
actual
field strengths is only 2 percent.

Reg, concerning the difference in ground characteristics with frequencies
above
3.5 MHz, please consider this. When the radials are long enough, and
enough of
them spaced sufficiently close, the effect is that of nearly perfect
ground,
regardless of the actual ground characteristics beneath the radials. Let's
consider a comparison. First, few radials widely spaced. Displacement
currents
reach the ground everywhere surrounding the vertical radiator. Currents
entering
the ground between the radials diffract toward the nearest radial of
higher
conductivity. During its travel toward the radial it naturally encounters
the
resistance of the ground. However, with many radials more closely spaced,
currents now entering the ground have a shorter resistance path in
reaching the
nearest radial, approaching a negligible value.

My point is that when there is a sufficient number of radials of
sufficient
length to approach a nearly-perfect ground, the ground characteristics
beneath
the radials are irrelevant within the area they cover in determining the
terminal impedance and efficiency of the radiator. Therefore, the
different gr
ound characteristics that prevail as the frequency increases above 3.5
MHz are
also irrelevant. This is not to say that the ground characteristics away
from
the immediate area are not important.

You might get a chuckle concerning the number of radials being 113. The
original
plan was to plow in 100 radials. When the grunts Jess Epstein and Bob
Lewis had
plowed in the intended 100 there was wire left over on the spool. They
asked
Brown what they should do with the remaining wire, he said, "Plow it in."
The
remainder of the wire allowed just 13 more radials to be plowed in.

On a personal note, I engineered and built WCEN in Mt. Pleasant, Michigan,
500 w
on 1150 Kc (it was 'Kc' then), with a 300' Blau-Knox tower. I plowed in
120
radials. My Dad manufactured the plow, which I rode, while he drove the
tractor.

Hope this keeps ya busy fer a while,

Walt, W2DU

I'm often confronted with problems as a physicist where one can only get a
handle on upper and lower bounds.
Lower bound:
I'd say the minimum number and length of radials is 3 (must define a plane)
and 1/4 wavelength (satisfies boundary conditions).

Upper (infinite sheet of copper)
As Walt and Reg have debated, the "Cleese extreme" (to steal from Reg's
post) is trying to duplicate the "infinite perfectly conducting plane" of
our elementary physics books.
Cheers and beers
H.

73, NQ5H

"H. Adam Stevens, NQ5H" wrote
I'm often confronted with problems as a physicist where one can only
get a
handle on upper and lower bounds.
Lower bound:
I'd say the minimum number and length of radials is 3 (must define a
plane)
and 1/4 wavelength (satisfies boundary conditions).

Upper (infinite sheet of copper)
As Walt and Reg have debated, the "Cleese extreme" (to steal from
Reg's
post) is trying to duplicate the "infinite perfectly conducting
plane" of
our elementary physics books.
Cheers and beers

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

Yes Adam, a logical way of looking at it.

Associated with any number there is always another number which is
sometimes, but not often enough, used to describe its uncertainty.

But nearly always it takes much longer to determine the uncertainty
than it does to arrive at the first number, especially if the first
number is the result of a measurement.
----
Reg.

On Sun, 23 Jul 2006 06:24:02 +0100, "Reg Edwards"
wrote:


"Walter Maxwell" wrote
The graphs reporting BLE's measurements are pretty conclusive. In
addition, the
BLE paper is the basis on which the FCC set the requirements for
the
ground
systems on all AM BC stations since 1939

==========================================
My point is that when there is a sufficient number of radials of
sufficient
length to approach a nearly-perfect ground, the ground
characteristics beneath
the radials are irrelevant within the area they cover in determining
the
terminal impedance and efficiency of the radiator. Therefore, the
different gr
ound characteristics that prevail as the frequency increases above
3.5 MHz are
also irrelevant.
Walt, W2DU
============================================

Dear Walt,

At risk of upsetting a great number of patriotic USA citizens, all BLE
hero-worshippers, I admit to having speed-read BLE's lengthy paper
some years back. Their conclusion, that with a sufficiant number and
length of radials the ground characteristics are irrelevant, is so
glaringly apparent they could have stayed in their offices and saved a
great deal of expense and copper wire. I am reminded of John Cleese's
remark "They must have had first-class honors degrees in stating the
bleeding obvious".

Because BL&E omitted to measure ground conductivity and permittivity
on the site their conclusion amounted to making a virtue out of a vice
and Marzipan the Magician's magic number of 120 came into existence.
Their sponsors should have made them go back to finish the job.

In the absence of any other information at the time, the fact of
irrelevance was of interest to LF and MF broadcasters with money to
burn, but it was, and still is, of no use to radio amateurs, confined
to the HF bands with limited purses, small back yards and XYL's to
keep happy.

My small program Radial_3 has been singled out and I have been accused
of disagreeing in a disruptive, almost criminal manner with BL&E's
conclusions. This is patently untrue! The program has nothing to do
with BL&E except that it deals with a similar subject in terms
appropriate to amateurs and draws its own independent conclusions.

Your absence caused a little worry. Glad to hear you were only
working.
----
Reg.

Reg, I appreciate your worry about my absence.

However, concerning the 'obviousness' of the conditions when there are enough
radials to simulate perfect ground, you must remember that it was not 'obvious'
in 1937. Prior to that time most BC 'aerials' were in the form of a 'T', a
horizontal wire (top-hat loading) supported by two towers, dangling a vertical
wire (the radiator) from the center, down to the antenna tuner. The 'ground'
system was a wire counterpoise, because very little was known about any other
type of 'ground' to work the vertical against.

Brown originated the concept of radials to improve the conductivity (meaning
reducing the resistance) of the ground, simply to avoid the construction of a
messy arrangement of wires to get tangled up in. But before presenting the
suggestion of radials to the world he proved it would work by performing the BLE
experiment.

Brown also is responsible for the tower antennas being of uniform shape over its
entire length, where before it was customary to use the diamond shape. With the
diamond shape the field strength measurements didn't follow the theory. Using
models for measurements he determined that the current on the diamond shape does
not flow uniformly, which resulted in undesirable radiation patterns. He then
demonstated that when the tower construction was of uniform cross section the
current became uniform and the radiation patterns became uniform and more
predictable and useful.

After proving the concept with models, he worked with John Leitch, chief
engineer of WCAU Philadelphia, in proving that it worked with full-size towers.
The WCAU tower was diamond shaped. The experiments with WCAU, and subsequently
with a tower of uniform cross section, proved the concept to be correct.

The result of Brown's experiment with the shape of the tower is that as of 1940,
the FCC mandated use of towers with uniform cross section for all new
installations. In addtion, no changes of any kind in the transmitting system
were permitted in stations that didn't already have a tower with uniform cross
section until the present antenna system was changed to one having uniform cross
section. Brown's influence on BC antenna systems is legendary. He also patented
the concept of using loading coils to shorten the physical length of towers.
Some towers that followed his lead have insulators between sections and an
inductance connecting them.

Brown's article, "Directional Antennas," appearing in a 1937 issue of the IRE,
formed the theoretical basis for all directional BC antennas

Brown also invented and patented the ground plane antenna for VHF and UHF. All
of his antenna experimentation was as an engineer with RCA. It was a great
experience for me to have worked in Brown's antenna lab along with guys like
Jess Epstein, O.M. Woodward, and Donald Peterson.

Walt,W2DU

These are very good points. I am reading these postings to try to
understand the behavior of actual implementations that lie somewhere between
the extremes you pointed out. In other words, what gets you the most bang
for the buck.... How fast does performance change with increased radial
length and number of radials.


"H. Adam Stevens, NQ5H" wrote in message
...
I'm often confronted with problems as a physicist where one can only get a
handle on upper and lower bounds.
Lower bound:
I'd say the minimum number and length of radials is 3 (must define a
plane) and 1/4 wavelength (satisfies boundary conditions).

Upper (infinite sheet of copper)
As Walt and Reg have debated, the "Cleese extreme" (to steal from Reg's
post) is trying to duplicate the "infinite perfectly conducting plane" of
our elementary physics books.
Cheers and beers
H.

73, NQ5H

"Reg Edwards" wrote in message
...

"H. Adam Stevens, NQ5H" wrote
I'm often confronted with problems as a physicist where one can only
get a
handle on upper and lower bounds.
Lower bound:
I'd say the minimum number and length of radials is 3 (must define a
plane)
and 1/4 wavelength (satisfies boundary conditions).

Upper (infinite sheet of copper)
As Walt and Reg have debated, the "Cleese extreme" (to steal from
Reg's
post) is trying to duplicate the "infinite perfectly conducting
plane" of
our elementary physics books.
Cheers and beers

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

Yes Adam, a logical way of looking at it.

Associated with any number there is always another number which is
sometimes, but not often enough, used to describe its uncertainty.

But nearly always it takes much longer to determine the uncertainty
than it does to arrive at the first number, especially if the first
number is the result of a measurement.
----
Reg.



That got a chuckle.
I'm an EXPERIMENTAL physicist.
;^)