Brown, Lewis & Epstein
 

There has been considerable discussion on the antenna news group
regarding ground systems for monopole antennas. Invariably, a
reference is made to a study prepared by Brown, Lewis, and Epstien
that was published in the proceedings of the IRE in 1937.
Unfortunately, many amateurs do not live near a major library or
university where they would be able to obtain a copy of this paper.

Therefore, I have placed on my web site a scanned copy of "Ground
Systems As A Factor In Antenna Efficiency" by G.H. Brown, R.F. Lewis
and J. Epstein which was publish by Institute of Radio Engineers in
June 1937. This scanned copy is identical in format as a copy I
obtained from the library.

Be advised that you need Adobe Reader for viewing. Additionally, this
is a rather large file (about 3MB).

You may view this document at:

http://users.adelphia.net/~k6mhe/BLE.html

73,
Danny, K6MHE

Thank you Sir!

"Dan Richardson arrl net" k6mheatdot wrote in message
...
There has been considerable discussion on the antenna news group
regarding ground systems for monopole antennas.

Thank you, Thank you, Thank you.

Charlie

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

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

"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
...
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