Dan:

I cannot thank you enough for taking the time to scan and post this
article. It is almost impossible to find articles that old that are
still legible. This is an example of the spirit of HAM radio.

Have a great 4th of July holiday.

73, Lew

(I have tried unsuccessfully to make the tabular data in the msg below come out
correctly. I apologize for that and hope you can interpret the data
successfully. Walt,W2DU)

Thanks to Richard Harrison, he has supplied us with the renowned Brown, Lewis
and Epstein paper, reporting the voluminous and enlightening experimental data
concerning the length and number of ground radials required in approaching the
condition of perfect ground underneath a vertical radiator. This paper has long
been well known and highly respected in the communications engineering
community, and since 1938 has become the standard for engineering the radial
systems for AM BC stations Worldwide. The FCC requirement for radials in US BC
stations is based on data in the BLE paper.

The tragedy here is that BLE paper has gone practically unknown in the amateur
community, as witnessed by so many continual questions and incorrect answers
concerning the length and number of radials required to achieve the desired
performance of our vertical radiators.

So let me present a short, but definitive abstract of the pertinent numbers
taken from the paper, that answer some of the pertinent questions correctly.

As a reference on which to base the radiated field strength, the industry
standard has traditionally used millivolts per meter to describe field strength.
Specifically, the field strength of 194.5 millivolts per meter at one mile,
radiated from a quarter-wavelength radiator over perfect ground with 1000 watts
input, is the industry standard. In other words, this field strength is the
maximum attainable under ideal conditions. The data below, obtained directly
from measurements made at 3 MHz by Brown, Lewis and Epstein in 1937, provide
definitive answers to those who ask how many radials of what length are
necessary to provide a suitable ground plane. When comparing the fields
strengths below, remember that 194.5 mv/meter is the field strength obtained
with perfect lossless ground.

Number of Field Strength Loss in dB Relative

Radials in mv/meter to Perfect Ground

Length Length

0.4 wl 1/4 wl 1/8 wl 0.4 wl 1/4 wl 1/8 wl

113 192 180 152 0.112 0.673 2.14

60 185 176 150 0.435 0.868 2.26

30 174 162 150 0.967 1.59 2.26

15 158 153 1.81 2.08

2 126 120 118 3.77 4.19 4.39

When reviewing these data, please keep in mind that as the field strength
approaches 194.5 mv/meter the effective ground is approaching perfect ground,
which means that the conductivity of the ground in which the radials are planted
is irrelevant, only the ground external to the radial system is relevant with
respect to conductivity.

It should also be kept in mind that the energy in the EM fields surrounding the
vertical radiator diminishes with distance from the radiator. Thus the
displacement currents entering the ground diminish proportionately with
distance. Consequently, there is a distance from the radiator after which the
currents become too small to be significant to the conservation of power
radiated. This fact determines the maximum length of the radials necessary to
reach the point where the law of diminishing returns prevails. The measurements
reported in the BLE paper show this distance to be between 0.4 and 0.5
wavelengths. As noted above, this distance is relative to the amount of energy
in the displacement currents at this distance from the radiator, and is in no
way relevant to any resonant length of the radial. It is well known that radials
buried in the ground lose all sense of resonance.

Walt, W2DU

Man, O, Man, do I have some apologizing to do to Danny Richardson, K6JHE. Danny
is the one who supplied the data on the Brown, Lewis and Epstein paper, not
Richard Harrison.

I'm sorry, Danny, it was a senior moment at age 86 that's responsible.

Walt, W2DU

On Fri, 1 Jul 2005 16:57:19 -0400, "Walter Maxwell"
wrote:

Man, O, Man, do I have some apologizing to do to Danny Richardson, K6JHE. Danny
is the one who supplied the data on the Brown, Lewis and Epstein paper, not
Richard Harrison.

I'm sorry, Danny, it was a senior moment at age 86 that's responsible.

Walt, W2DU

Not a problem Walt. Now had I never made any errors............ G

Very 73 my friend,

Danny,
K6MHE

"Walter Maxwell" wrote in message
...
Man, O, Man, do I have some apologizing to do to Danny Richardson, K6JHE.
Danny is the one who supplied the data on the Brown, Lewis and Epstein paper,
not Richard Harrison.

I'm sorry, Danny, it was a senior moment at age 86 that's responsible.

Walt, W2DU

Dang, I can't seem to get anything right today. Can't even spell Danny's call
sign correctly. Repeat after me, it's K6MHE, it's K6MHE, it's K6MHE.

Walt, W2DU

Walt, while this would be wonderful information if I were broadcasting
during the day on 75 meters, how is it applicable to those of us who don't
care about groundwave?

"Walter Maxwell" wrote in message
...
(I have tried unsuccessfully to make the tabular data in the msg below
come out

"Fred W4JLE" wrote in message
...
Walt, while this would be wonderful information if I were broadcasting
during the day on 75 meters, how is it applicable to those of us who don't
care about groundwave?

Well, Fred, it's because it has everything to do with how much of your xmtr
power is heating the ground vs how much is being radiated at whatever frequency
you're using. We're not even talking about ground wave, it's how much power is
radiated, period.

Walt

So as I understand it, as I add more radials, my field strength should
increase regardless of the elevation angle. Assuming I make all measurements
at the same point.


"Walter Maxwell" wrote in message
...

"Fred W4JLE" wrote in message
...
Walt, while this would be wonderful information if I were broadcasting
during the day on 75 meters, how is it applicable to those of us who
don't
care about groundwave?

Well, Fred, it's because it has everything to do with how much of your
xmtr
power is heating the ground vs how much is being radiated at whatever
frequency
you're using. We're not even talking about ground wave, it's how much
power is
radiated, period.

Walt

"Fred W4JLE" wrote in message
...
So as I understand it, as I add more radials, my field strength should
increase regardless of the elevation angle. Assuming I make all measurements
at the same point.


"Walter Maxwell" wrote in message
...

"Fred W4JLE" wrote in message
...
Walt, while this would be wonderful information if I were broadcasting
during the day on 75 meters, how is it applicable to those of us who
don't
care about groundwave?

Well, Fred, it's because it has everything to do with how much of your
xmtr
power is heating the ground vs how much is being radiated at whatever
frequency
you're using. We're not even talking about ground wave, it's how much
power is
radiated, period.

Walt

Fred, the radials affect only the efficiency of the radiator--power lost in the
ground resistance vs power radiated. The take off, or elevation angle is
determined by the ground conductivity external to the radial system, the poorer
the ground the less power will radiate at low elevation angles. In other words,
the better the ground conductivity external to the radial system the lower the
elevation angle of the maximum radiation. If the conductivity was perfect at an
infinite distance away from the radiator the elevation angle of the maximum
radiation lobe would be zero degrees.

Walt, W2DU

"Fred W4JLE" wrote in message
...
Walt, while this would be wonderful information if I were broadcasting
during the day on 75 meters, how is it applicable to those of us who don't
care about groundwave?

Well, Fred, it's because it has everything to do with how much of your xmtr
power is heating the ground vs how much is being radiated at whatever frequency
you're using. We're not even talking about ground wave, it's how much power is
radiated, period.

Walt