"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

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

On Fri, 1 Jul 2005 17:12:44 -0400, "Fred W4JLE"
wrote:

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?

I think you may have miss the point Fred... Its about antenna
efficiency.

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

Sorry about the multiple postings above. My moronic computer told me each time
that the msg could not be sent, so I kept trying.

Walt, W2DU

Maybe this will help clarify it. . .

As Walt and Danny said, this is all about efficiency -- the fraction of
your applied power that gets used heating the ground. So the ground wave
and sky wave are reduced by the same fraction. Just look at those dB
values in the right hand column of Walt's summary, and they'll apply to
75 meter sky wave as well as to ground wave.

They won't be exact, of course, since they depend on both ground
characteristics (to quite a fair depth) and frequency. But they're as
good a set of working values as you'll find.

Roy Lewallen, W7EL

Dan Richardson k6mheatarrl wrote:
On Fri, 1 Jul 2005 17:12:44 -0400, "Fred W4JLE"
wrote:


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?


I think you may have miss the point Fred... Its about antenna
efficiency.

Danny,
K6MHE

"Walter Maxwell" wrote:
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.

BL&E measured the groundwave field strength generated by a 200 milliwatt
carrier 0.3 miles from a vertical radiator. This value was converted to
equivalent field for 1 kW of radiated power at a distance of 1 mile. With
this technique, and with 113 each 0.412-wave radials, they found that their
measured/converted field was less than 0.1124 dB below the theoretical value
for it over a perfect ground plane. These results demonstrate that the
consideration of ground conductivity during this study over this short path
was unnecessary (REG, please note).

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.

And that was for 113 radials. If only a few radials are used, BL&E report
that it is pointless to extend them that far.

RF

"Richard Fry" wrote in message
...
"Walter Maxwell" wrote:
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.

BL&E measured the groundwave field strength generated by a 200 milliwatt
carrier 0.3 miles from a vertical radiator. This value was converted to
equivalent field for 1 kW of radiated power at a distance of 1 mile. With
this technique, and with 113 each 0.412-wave radials, they found that their
measured/converted field was less than 0.1124 dB below the theoretical value
for it over a perfect ground plane. These results demonstrate that the
consideration of ground conductivity during this study over this short path
was unnecessary (REG, please note).

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.

And that was for 113 radials. If only a few radials are used, BL&E report
that it is pointless to extend them that far.

RF

Correct on both counts, Richard, thanks for reminding Reg, I forgot to. Did I
mention that I had the privilege of working at Brown's RCA antenna lab along
side Epstein for several years? Bob Lewis had left RCA when I arrived, but I
knew him later as a ham, W2EBS.

Walt, W2DU

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

"Walter Maxwell"
Correct on both counts, Richard, thanks for reminding Reg, I forgot to.
Did I mention that I had the privilege of working at Brown's RCA antenna
lab along side Epstein for several years? Bob Lewis had left RCA when I
arrived, but I knew him later as a ham, W2EBS.
_______________

That would have been a privilege. When with RCA I worked a bit with Matti
Siukola, Oded Ben-Dov, Nick Nikolayuk and others at the RCA broadcast
antenna design center and test range at Gibbsboro, NJ . Great facility in
those days.

RF