On Sun, 4 Sep 2005 22:24:24 -0500, (Richard
Harrison) wrote:

Reg, G4FGQ wrote:
"The rods are both wasted effort and wasted copper (or aluminum)."

Likely so.

Radials are placed to capture displacement current to and from the
vertical radiator, to prevent its travel at a high densitY in the earth
where it would cause high loss.

B, L, & E found that more radials were better than longer radials. More
radials put the displacement current capture closer to the vertical
radiator where its density is higher. Radials need extend outward only
as far as there is any current or until a point of diminishing returns
is reached. At great distance from the vertical radiator, the earth`s
crust, which may be affected, has a great cross section, so current
density is low and so are losses. There is much less displacement
current to deal with near the ends of radials. Displacement current is
low near the ends of the radials and the earth out there has a large
cross section and a low resistance. Due to skin effect, the closer to
the surface, the higher the current. This is especially true at high
frequencies.

Hi Richard,

You've just presented the best abstract of BL&E I've seen ever seen.
It should be must reading for anyone who asks questions concerning the
purpose of radials, how many, and how long.

Walt, W2DU

The best answer I've seen, based on current research is:

N=(SQRT(2*PI*L))/A

N equals the square root of the quantity 2*PI*L divided by A, whe

N = optimum number of radials for high efficiency
L = amount of wire available in meters
A = distance between wire tips at the far end (a measure of radial density)

A = 1.3 for 95% or greater efficiency (approximation) read article for more
precise values.
A = 2.6 for 85% efficiency (approximation)

Example 1:

You have 500 meters of wire available. How many and how long for the two
values of A?

N = (SQR(2*pi*500))/1.3 = 43 radials. Length = 500/43 = 11.6 meters

N= (SQR(2*pie*500))/2.6 = 22 radials. Length = 500/22 = 18 meters

Example 2: (you have space constraints and the max radial length available
is 15 meters)

How many radials are required and how much wire is required?

The circumference of a circle with a radius of 15 meters is 2*PI*15 or 94.2
meters. With the tips of the radials seperated by 1.3 meters we have
94.2/1.3 = 72 radials. If we go for slightly more loss, we have 94.2/2.6 or
36 radials, 15 meters long.

Now you can plug in your own limitations for radial length, and get a feel
for how many of them you will need for 95% efficiency (A=1.3 meters) and 85%
(A=2.6 meters).

This info was presented in some ARRL publication, as I recall, and is also
presented in the 4th Edition of "Low-Band DXing" by John Devodere.

....hasan, N0AN

"Walter Maxwell" wrote in message
...
On Sun, 4 Sep 2005 22:24:24 -0500, (Richard
Harrison) wrote:

Reg, G4FGQ wrote:
"The rods are both wasted effort and wasted copper (or aluminum)."

Likely so.

Radials are placed to capture displacement current to and from the
vertical radiator, to prevent its travel at a high densitY in the earth
where it would cause high loss.

B, L, & E found that more radials were better than longer radials. More
radials put the displacement current capture closer to the vertical
radiator where its density is higher. Radials need extend outward only
as far as there is any current or until a point of diminishing returns
is reached. At great distance from the vertical radiator, the earth`s
crust, which may be affected, has a great cross section, so current
density is low and so are losses. There is much less displacement
current to deal with near the ends of radials. Displacement current is
low near the ends of the radials and the earth out there has a large
cross section and a low resistance. Due to skin effect, the closer to
the surface, the higher the current. This is especially true at high
frequencies.

Hi Richard,

You've just presented the best abstract of BL&E I've seen ever seen.
It should be must reading for anyone who asks questions concerning the
purpose of radials, how many, and how long.

Walt, W2DU

I appreciate Walt, W2DU`s kind words regarding my posting about ground
rods and radials.

I did not recommend any particular number or length of radials. RCA`s
Brown, Lewis, and Epstein examined how many and how long ground radials
should be in the 1930`s. The FCC accepted their experimental work,
conducted at 3 MHz, and used it to set ground system standards for
broadcasting in the medium wave band. These standards are still
applicable. B.L.&E. did good work.

Another RCA alumnus, E.A. Laport, abstracted some of B.L.&E.`s work in
"Radio Antenna Engineering". Figs. 2.17, 2.18, and 2.19 on pages 119 and
120 show field strength as a function of the number of radials. All the
Figs. show near perfection with 113 radials, so it seems the FCC rounded
up to 120 radials and made it the rule. It`s worked well, giving us
good broadcast reception when the earth is dry and sandy or wet and
swampy. Laport`s figures show performance with 1/2 and 1/4 the ideal
number of radials.

As Walter flattered me, I`ll reciprocate. Get hold of the April 1973
issue of QST. Look on page 35. Walter is pictured there. He is a real
good looking fellow!

Best regards, Richard Harrison, KB5WZI

On Mon, 5 Sep 2005 15:31:18 -0500, (Richard
Harrison) wrote:
[snip]
As Walter flattered me, I`ll reciprocate. Get hold of the April 1973
issue of QST. Look on page 35. Walter is pictured there. He is a real
good looking fellow!
[snip]

If you don't have that QST handy you can see Walter he

http://users.adelphia.net/~k6mhe/BLE_de_W2DU.html

73,
Danny, K6MHE

On Mon, 05 Sep 2005 14:25:09 -0700, Dan Richardson wrote:

On Mon, 5 Sep 2005 15:31:18 -0500, (Richard
Harrison) wrote:
[snip]
As Walter flattered me, I`ll reciprocate. Get hold of the April 1973
issue of QST. Look on page 35. Walter is pictured there. He is a real
good looking fellow!
[snip]

If you don't have that QST handy you can see Walter he

http://users.adelphia.net/~k6mhe/BLE_de_W2DU.html

73,
Danny, K6MHE


Well, Danny, ya had to go and do it din't ya? Now people who see my
face in post offices will know how to trace me through my mug shot you
just posted. I thought I'd gotten away with it. Somebody hire you to
post it? CSI? Law & Order? At least after I'm sent away to Attica
everybody, including you, will be able to find me.

Ya wanna know sumptin? I don't even have any remorse!

Walt

On Mon, 05 Sep 2005 21:32:45 -0400, Walter Maxwell
wrote:

Well, Danny, ya had to go and do it din't ya? Now people who see my
face in post offices will know how to trace me through my mug shot you
just posted. I thought I'd gotten away with it. Somebody hire you to
post it? CSI? Law & Order? At least after I'm sent away to Attica
everybody, including you, will be able to find me.

Ya wanna know sumptin? I don't even have any remorse!

Walt

The devil made me do it! G

Danny

On Mon, 05 Sep 2005 14:25:09 -0700, Dan Richardson wrote:

On Mon, 5 Sep 2005 15:31:18 -0500, (Richard
Harrison) wrote:
[snip]
As Walter flattered me, I`ll reciprocate. Get hold of the April 1973
issue of QST. Look on page 35. Walter is pictured there. He is a real
good looking fellow!
[snip]

If you don't have that QST handy you can see Walter he

http://users.adelphia.net/~k6mhe/BLE_de_W2DU.html

73,
Danny, K6MHE

Danny, I was just perusing the data in the post re the above url and
found a typo. In the ground radial data in the line showing 30
radials, the data for 0.4/wl indicating 158 mv/meter should read 185
mv/meter.

I've searched through my files for the one I sent to you containing
this data, but I can't find it. I'm assuming you simply copied my
data, so it's probably my error, which I'd like to fix in the
original. I guess all I can do is ask you to place a correction on
that incorrect piece of data to avoid giving the impression that the
remaining data may be suspect.

Walt, W2DU

On Mon, 05 Sep 2005 22:22:37 -0400, Walter Maxwell
wrote:

On Mon, 05 Sep 2005 14:25:09 -0700, Dan Richardson wrote:

On Mon, 5 Sep 2005 15:31:18 -0500, (Richard
Harrison) wrote:
[snip]
As Walter flattered me, I`ll reciprocate. Get hold of the April 1973
issue of QST. Look on page 35. Walter is pictured there. He is a real
good looking fellow!
[snip]

If you don't have that QST handy you can see Walter he

http://users.adelphia.net/~k6mhe/BLE_de_W2DU.html

73,
Danny, K6MHE

Danny, I was just perusing the data in the post re the above url and
found a typo. In the ground radial data in the line showing 30
radials, the data for 0.4/wl indicating 158 mv/meter should read 185
mv/meter.


I think you mean the line for 60 radials? Anyway I changed that one to
the 185 figure.

Please double check it for me.

Thanks,
Danny, K6MHE

email: k6mheatarrldotnet
http://users.adelphia.net/~k6mhe/

On Mon, 05 Sep 2005 19:33:38 -0700, Dan Richardson wrote:

If you don't have that QST handy you can see Walter he

http://users.adelphia.net/~k6mhe/BLE_de_W2DU.html

73,
Danny, K6MHE

Danny, I was just perusing the data in the post re the above url and
found a typo. In the ground radial data in the line showing 30
radials, the data for 0.4/wl indicating 158 mv/meter should read 185
mv/meter.


I think you mean the line for 60 radials? Anyway I changed that one to
the 185 figure.

Please double check it for me.

Thanks,
Danny, K6MHE

email: k6mheatarrldotnet
http://users.adelphia.net/~k6mhe/

Ya done good, Danny, thanks.

Walt

On Mon, 5 Sep 2005 15:31:18 -0500, (Richard
Harrison) wrote:

I appreciate Walt, W2DU`s kind words regarding my posting about ground
rods and radials.

I did not recommend any particular number or length of radials. RCA`s
Brown, Lewis, and Epstein examined how many and how long ground radials
should be in the 1930`s. The FCC accepted their experimental work,
conducted at 3 MHz, and used it to set ground system standards for
broadcasting in the medium wave band. These standards are still
applicable. B.L.&E. did good work.

Another RCA alumnus, E.A. Laport, abstracted some of B.L.&E.`s work in
"Radio Antenna Engineering". Figs. 2.17, 2.18, and 2.19 on pages 119 and
120 show field strength as a function of the number of radials. All the
Figs. show near perfection with 113 radials, so it seems the FCC rounded
up to 120 radials and made it the rule. It`s worked well, giving us
good broadcast reception when the earth is dry and sandy or wet and
swampy. Laport`s figures show performance with 1/2 and 1/4 the ideal
number of radials.

As Walter flattered me, I`ll reciprocate. Get hold of the April 1973
issue of QST. Look on page 35. Walter is pictured there. He is a real
good looking fellow!

Best regards, Richard Harrison, KB5WZI

Thank you, Richard, for considering me for the MAS (mutual admiration
society). You are too kind. The issue of QST you referenced contains
the first installment of my series of articles, "Another Look At
Reflections," which form the first seven chapters of 'Reflections 1
and 2'. Incidentally, the 3rd edition is in the publication stage. I
will be posting the release date on my web page at w2du.com.

Back on the subject of radials, unless the FCC has changed the
requirements since I was involved, the requirement is for 90 radials.
However, most of the AM BC stations I'm familiar with use 120, even
tho not required.

Walt, W2DU