Tom Donaly wrote:
I doubt whether there's a grape vine in the world that cares
who is president of the U.S.

The grapevine around Madison County, TX was buzzing with
the news of Bush's re-election on the morning of Nov. 3.

Richard,

I am quite familiar with standing waves, thank you. I have no
disagreements with Terman, Kraus, Balanis, or any other legitimate experts.

You can reread what I said, if you care to understand, rather than pick
a sentence out of context.

73,
Gene
W4SZ



Richard Harrison wrote:
Gene, W4SZ wrote:
"Standing waves are not static."

Incredible!

My "American College dictionary" defines "standing wave": "a
distribution of wave displacements , such that the distribution in space
is periodic, with fixed maximum and minimum points, with the maxima
occuring everywhere at the same time, as in vibration of strings,
electric potentials, acoustic pressures, etc."

Note the word "fixed" in the definition. That`s a synonym for "static".

For how this applies to antennas and transmission lines, see page 177 of
Kraus` "Antennas", third edition, Figure 6-7. Notice that current
reverses 1/2-wavelength back from the antenna`s open-circuit endjust as
it does in the case of the open-circuit transmission-line, as shown by
Terman on page 92 of "Electronic and Radio Engineering", 1955 edition,
and on page 94 in FiG. 4-5 (a). This all starts at the reflection point
and progresses the same regardless of the length of the antenna or
transmission-line. It is due to superposition of the forward and
reflected waves, just as Cecil maintains.

Advice: Never argue with Kraus and Terman.

Best regards, Richard Harrison, KB5WZI

Gene Fuller wrote:
I am quite familiar with standing waves, thank you. I have no
disagreements with Terman, Kraus, Balanis, or any other legitimate experts.

Question is: Why do you promote W8JI's stuff when it is quite obvious
that he is NOT familiar with standing waves. If he were familiar with
standing waves, he wouldn't be asserting that net standing wave current
flows into the bottom of the loading coil and out the top of the loading
coil. Are you absolutely sure that you want to promote the alleged
"information" on W8JI's web page as absolute fact? If he is so right
and so capable of defending his assertions, why isn't he here right
now? (Trying to get W8JI to follow me down the Primrose Path :-) as
he did when he asserted that "differential" effects are "completely
unrelated" to "common mode" effects.)
--
73, Cecil, W5DXP

Reg Edwards wrote:

The only program I am reasonably familiar with is the several years old free
EZNEC. I don't know whether it has been updated or not and I make very
little use of it. Come to think of it, I don't make much use of my own
programs either.

Regarding shallow buried radials in conjunction with a vertical, have you
tried my recent program RADIALS2 ?

It is intended to demonstrate performance of the radials themselves in a
given ground rather than antenna performance. Which I suspect is the reverse
of NEC-4.

As you probably know, the effects of above-ground radials change very
rapidly as they get within a few inches of the ground surface. But once in
the ground they tend to remain static.

RADIALS2 uses an entirely different, unconventional form of performance
analysis. If other programs don't take soil permittivity into account at HF,
predictions must lose accuracy. Are the inputs and outputs of NEC-4 in a
form suitable for a direct comparison with my simple program?

Yes. I made a few comparisons long ago, shortly after you introduced
your program, and found major disagreement. NEC-4 approximately agrees
with the measurements made long ago by Brown, Lewis, and Epstein (whom I
know you've never heard of), once you make reasonable assumptions of
ground conductivity and dielectric constant. Your program gives very
different answers. At the time, I concluded that there's considerable
coupling between radials, which your program doesn't seem to account
for. Interested readers should look in the google archives for postings
in this group on the thread "Ground Radials" in July 1998 and
"Evaluation of G4FGQ Freeware Antenna Software" in September 1998.


But in view of the large uncertainties involving ground conditions, accuracy
is not worth making much of a song and dance about.

True, but in the past, you've used the results from your program to
reach conclusions about radial systems that I didn't, and don't, believe
to be valid. (See the threads mentioned above.) I don't think it's wise
to draw conclusions from a program that gives results which are
demonstrably very different from the only measurements regarded to be
reasonably well made.

Roy Lewallen, W7EL

"Roy Lewallen" wrote in message
...
Reg Edwards wrote:

The only program I am reasonably familiar with is the several years old
free
EZNEC. I don't know whether it has been updated or not and I make very
little use of it. Come to think of it, I don't make much use of my own
programs either.

Regarding shallow buried radials in conjunction with a vertical, have
you
tried my recent program RADIALS2 ?

It is intended to demonstrate performance of the radials themselves in a
given ground rather than antenna performance. Which I suspect is the
reverse
of NEC-4.

As you probably know, the effects of above-ground radials change very
rapidly as they get within a few inches of the ground surface. But once
in
the ground they tend to remain static.

RADIALS2 uses an entirely different, unconventional form of performance
analysis. If other programs don't take soil permittivity into account at
HF,
predictions must lose accuracy. Are the inputs and outputs of NEC-4 in
a
form suitable for a direct comparison with my simple program?

Yes. I made a few comparisons long ago, shortly after you introduced
your program, and found major disagreement. NEC-4 approximately agrees
with the measurements made long ago by Brown, Lewis, and Epstein (whom I
know you've never heard of), once you make reasonable assumptions of
ground conductivity and dielectric constant. Your program gives very
different answers. At the time, I concluded that there's considerable
coupling between radials, which your program doesn't seem to account
for. Interested readers should look in the google archives for postings
in this group on the thread "Ground Radials" in July 1998 and
"Evaluation of G4FGQ Freeware Antenna Software" in September 1998.


But in view of the large uncertainties involving ground conditions,
accuracy
is not worth making much of a song and dance about.

True, but in the past, you've used the results from your program to
reach conclusions about radial systems that I didn't, and don't, believe
to be valid. (See the threads mentioned above.) I don't think it's wise
to draw conclusions from a program that gives results which are
demonstrably very different from the only measurements regarded to be
reasonably well made.

Roy Lewallen, W7EL
==============================

Roy, it's gratifying to see, once again, you take notice of my sayings.

Such as, I repeat -

"Fact 4. Computer programs do not tell gospel truths. They are at least as
unreliable as their human programmers."
----
Reg.

Steve Nosko wrote:
"Play with words if U like."

The whole phenomenon is not static. The incident and reflected waves
move. It is their interference patterns, the standing waves, which are
static.

Cecil wisely called them the rms values. I assumed it understood that
the RF (a-c) voltages and currents are expressed as their rms values
unless otherwise specified. Everyone should know that a-c is an acronym
for alternating current which, of course, alternates,

Best regards, Richard Harrison, KB5WZI

Modeled #14 AWG, copper conductor, 32ft monopole, 29 radials of 25ft, and
base 6" above (nominal lambda/1000) Sommerfeld/Norton ground of Er = 13,
sigma = 0.013 S/m at 1.8 MHz. All segments 6".

NEC2 computes:
Zin = 2.87 - j1358 Efficiency 92%

RADIALS2 computes (with radials 1mm below ground):
Zin = 1.55 - j1310 Efficiency 23.5%

Not a large amount of difference, but thought I had gotten closer results
with a different monopole, but seem to have deleted the code (Not sure why
such a large difference in efficiency). NEC2 is supposed to provide a
reasonable approximation of a buried radial monopole when at about
lambda/1000 above ground. Be interested in any comments, and what NEC4
provides if anybody has it.

73,

Frank

"Roy Lewallen" wrote in message
...
Reg Edwards wrote:

The only program I am reasonably familiar with is the several years old
free
EZNEC. I don't know whether it has been updated or not and I make very
little use of it. Come to think of it, I don't make much use of my own
programs either.

Regarding shallow buried radials in conjunction with a vertical, have you
tried my recent program RADIALS2 ?

It is intended to demonstrate performance of the radials themselves in a
given ground rather than antenna performance. Which I suspect is the
reverse
of NEC-4.

As you probably know, the effects of above-ground radials change very
rapidly as they get within a few inches of the ground surface. But once
in
the ground they tend to remain static.

RADIALS2 uses an entirely different, unconventional form of performance
analysis. If other programs don't take soil permittivity into account at
HF,
predictions must lose accuracy. Are the inputs and outputs of NEC-4 in a
form suitable for a direct comparison with my simple program?

Yes. I made a few comparisons long ago, shortly after you introduced your
program, and found major disagreement. NEC-4 approximately agrees with the
measurements made long ago by Brown, Lewis, and Epstein (whom I know
you've never heard of), once you make reasonable assumptions of ground
conductivity and dielectric constant. Your program gives very different
answers. At the time, I concluded that there's considerable coupling
between radials, which your program doesn't seem to account for.
Interested readers should look in the google archives for postings in this
group on the thread "Ground Radials" in July 1998 and "Evaluation of G4FGQ
Freeware Antenna Software" in September 1998.


But in view of the large uncertainties involving ground conditions,
accuracy
is not worth making much of a song and dance about.

True, but in the past, you've used the results from your program to reach
conclusions about radial systems that I didn't, and don't, believe to be
valid. (See the threads mentioned above.) I don't think it's wise to draw
conclusions from a program that gives results which are demonstrably very
different from the only measurements regarded to be reasonably well made.

Roy Lewallen, W7EL

"Frank" wrote in message
news:H4hkd.141267$9b.112169@edtnps84...
Modeled #14 AWG, copper conductor, 32ft monopole, 29 radials of 25ft, and
base 6" above (nominal lambda/1000) Sommerfeld/Norton ground of Er = 13,
sigma = 0.013 S/m at 1.8 MHz. All segments 6".

NEC2 computes:
Zin = 2.87 - j1358 Efficiency 92%

RADIALS2 computes (with radials 1mm below ground):
Zin = 1.55 - j1310 Efficiency 23.5%

Not a large amount of difference, but thought I had gotten closer results
with a different monopole, but seem to have deleted the code (Not sure why
such a large difference in efficiency). NEC2 is supposed to provide a
reasonable approximation of a buried radial monopole when at about
lambda/1000 above ground. Be interested in any comments, and what NEC4
provides if anybody has it.

73,

Of course the higher efficiency is due to NEC calculating only the I^2R
losses, and not the TRP. TRP should be fairly easy to calculate since the
pattern is "phi" independent. Have not checked to see if there is a TRP
card.
Note that a 32 ft monopole mounted on a perfect ground has an input
impedance of 1.58 - j1311 Ohms. The efficiency is reduced to 86% due to
increased I^2R losses.

Frank

Gene Fuller wrote:
I am quite familiar with standing waves, thank you. I have no
disagreements with Terman, Kraus, Balanis, or any other legitimate experts.

What I am still not understanding, is since the exponential equations
for voltage and current in a transmission line are identical except
for the Z0 term, how can something happen to the current without
the same thing happening to the voltage at the same time? How can
something happen to the voltage without also happening to the current
at the same time? In a matched system, the voltage and current arrives
at the load at exactly the same time attenuated by exactly the same
amount. But that voltage didn't flow and that current didn't drop???
--
73, Cecil, W5DXP

On Thu, 11 Nov 2004 18:46:18 -0600, Cecil Moore
wrote:
the voltage and current arrives at the load at exactly the same time
Only if you skip a battery off someone's skull.