On Nov 15, 12:59*pm, Dave wrote:
On Nov 15, 4:14*pm, Art Unwin wrote:



On Nov 15, 6:18*am, Dave wrote:

On Nov 15, 6:23*am, Art Unwin wrote:

Cebic found when comparing different style programs that some behaved
well in certain circumstance where others did not. Yet all antenna
programs
are based on the use of Maxwells equations where all programs should
have the same results, after all Maxwells equations are exact and not
fudged. One of the reasons is that since Maxwells laws are exact
radiators used must be resonant at repeatable points designated as a
period.
* *Fact is that most users use fractional wavelength designs, usually
a half wavelength, that is not resonant at repeatable points where
the area around the datum line of a sine wave is never equal when
generated around a tank circuit.
* * The reason for this is "voltage over shoot" which gets smaller
with every cycle but never disappears. Thus when programs are used
based on fractional wavelength radiators the results will never show
100% accountability and in fact efficiencies derived will be in the
order of 92%!
* If the radiator is of a wavelength then one is not using a "fudge"
figure
in the calculations and *then becomes possible to attain total
accountability with efficiency of 100%. regardles of what type program
is used.
* *If one is to use exact equations, as are Maxwell equations, then
one must also use measurements that are also exact and repeatable and
that is definitely not fractional wavelengths!
*What one gains from this aproach is that any radiator of any shape,
*size or elevation can provide figures in the order of 100% as long as
the radiator is a multiple of a wavelength where it is *resonant at
exact and repeatable measurements.
If anybody can give pointers that refute the accuracy of the above I
would be very interested in hearing them

the key is that while all the programs are based on maxwell's
equations, it is impossible to implement maxwell's equations with 100%
accuracy on a digital computer. *this is true of any and all
simulation and modeling programs for electrical or mechanical design.
all such programs make approximations and take shortcuts to reduce
calculation time while maintaining some minimum level of accuracy and
precision. *it is important to understand the assumptions and
simplifications that have been made in order to make proper use of the
programs. *typical traps in antenna simulations are that they don't
like very small or very large length/diameter ratios... so using them
for extrement long or short wires or very fat or very thin wires may
produce results that aren't realistic. *many of them also don't like
very small spacing between wires, this is where most optimizer
programs fall apart, they start moving wires close together and get
strange results like super gain or unrealizable narrow beam patterns,
often accompanied by a very low feedpoint impedance.

most reputable programs like NEC have been validated very diligently
over many years and their accuracy is well documented... as are the
restrictions and assumptions that apply, but you have to read ALL the
documentation, not just the quick start guide. *Other programs like
mininec, ao, yo, yagimax, and others make even more simplifications
and therefore added restrictions so they can run on a desktop
relatively quickly. *unfortunately they don't always document the
limitations as well as the professional level products. *after all the
professionals have millions of dollars riding on the accuracy of
designs, hams have only pennies, so it just doesn't pay to write lots
of documentation or do lots of testing that won't be read for ham
users.

so, while all the programs must be based on the same equations, the
results they generate, especially in the fringe cases, may be vastly
different. *remember two maxims... 'garbage in - garbage out', and
'you get what you pay for'.

Exactly.
If one uses a "period" of a cycle or a full wave instead of fractional
wavelengths
Maxwell's equations can be used in antenna programs to achieve 100%
accountability
or efficiency Where as the fudge figure of fractional wavelengths can
only achieve efficiencies in the lower 90s unless voltage over shoot
is accounted for.
Programs with optimizers recognize over shoot by providing radiators
that are all multiples of a wavelength and resonant so that the array
is also resonant as a whole.- Hide quoted text -

- Show quoted text -

what exactly is 'voltage overshoot' and why does it affect modeling
programs? *you can model an antenna without ever calculating a
voltage. *all that is needed is current, which is usually much easier
to track. *all voltages can be calculated from the current after the
fact if needed for figuring insulation requirements.

When a energy switching action occurs as with energy exchange between
an inductance
and a capacitance a transient spur of voltage is created beyond the
point of balance or equilibrium of the circuit. Tho this is only
momentary, it delays the return of energy back to the capacitance to a
lesser time. The capacitor then returns the energy back to the
inductance but with a lesser voltage which again creates a transient
spike of a now lesser value than before, such that the amplitude of a
balanced "loss less" circuit is lost to one that defines vibration
which in the human ear also creates communication. (When delving into
the mathematical laws of vibration where the amplitude change and the
similarity to vibration can be readily be seen.
Any way, it can be seen that with the amplitude of vibration is ever
changing, so must the point where the amplitude is repeatable ie
resonant, must also change. Yes, you can model anything without ever
considering voltage when you choose to omit the presence of overshoot
for easability over accuracy.
Regards
Art
where the amplitude

On Nov 15, 8:10*pm, Art Unwin wrote:
On Nov 15, 12:59*pm, Dave wrote:





On Nov 15, 4:14*pm, Art Unwin wrote:

On Nov 15, 6:18*am, Dave wrote:

On Nov 15, 6:23*am, Art Unwin wrote:

Cebic found when comparing different style programs that some behaved
well in certain circumstance where others did not. Yet all antenna
programs
are based on the use of Maxwells equations where all programs should
have the same results, after all Maxwells equations are exact and not
fudged. One of the reasons is that since Maxwells laws are exact
radiators used must be resonant at repeatable points designated as a
period.
* *Fact is that most users use fractional wavelength designs, usually
a half wavelength, that is not resonant at repeatable points where
the area around the datum line of a sine wave is never equal when
generated around a tank circuit.
* * The reason for this is "voltage over shoot" which gets smaller
with every cycle but never disappears. Thus when programs are used
based on fractional wavelength radiators the results will never show
100% accountability and in fact efficiencies derived will be in the
order of 92%!
* If the radiator is of a wavelength then one is not using a "fudge"
figure
in the calculations and *then becomes possible to attain total
accountability with efficiency of 100%. regardles of what type program
is used.
* *If one is to use exact equations, as are Maxwell equations, then
one must also use measurements that are also exact and repeatable and
that is definitely not fractional wavelengths!
*What one gains from this aproach is that any radiator of any shape,
*size or elevation can provide figures in the order of 100% as long as
the radiator is a multiple of a wavelength where it is *resonant at
exact and repeatable measurements.
If anybody can give pointers that refute the accuracy of the above I
would be very interested in hearing them

the key is that while all the programs are based on maxwell's
equations, it is impossible to implement maxwell's equations with 100%
accuracy on a digital computer. *this is true of any and all
simulation and modeling programs for electrical or mechanical design.

On Nov 15, 12:23*am, Art Unwin wrote:

*What one gains from this aproach is that any radiator of any shape,
*size or elevation can provide figures in the order of 100% as long as
the radiator is a multiple of a wavelength where it is *resonant at
exact and repeatable measurements.

"Figures in the order or 100%" of what?

All radiators of all sizes and shapes will radiate on the order of
100% of all the r-f energy that can be coupled into them through their
input terminals, whether or not those conductor sizes/shapes are
naturally resonant at the applied frequency.

But the fact remains that natural resonance does not occur in
electrically small radiators -- while their radiation resistance is
very small, and their feedpoint is very reactive. These realities
make it very difficult to supply r-f power to such a radiator without
relatively high losses.

As a consequence, the efficiency of the transmitter SYSTEM
(transmitter + radiator + matching network, + r-f ground loss in the
case of monopoles) can be very low.

To illustrate, the link below leads to a calculation of the
performance of a 3-meter monopole system on 1500 kHz. Due to the low
radiation resistance and system losses, and even though the short
monopole itself is nearly 100% efficient at radiating the power across
its feedpoint, that radiator receives only about 0.37% of the power
available from the transmitter. So the system efficiency is very
poor.

Such an electrically short radiator (no matter what its shape) is not
very useful compared to a naturally resonant 1/4-wave monopole or 1/2-
wave dipole -- both of which can radiate nearly 100% of the available
power.

The calculations in the link below were made using standard equations,
in a spreadsheet format to make it easy to follow and confirm.
Properly constructed/used NEC models will verify the spreadsheet
calculation, and the statements about the dipoles mentioned above.

There is no cause to distrust NEC when it is properly understood and
properly used.

http://i62.photobucket.com/albums/h8...5on1500kHz.gif

RF

On Nov 15, 6:47*am, Richard Fry wrote:
On Nov 15, 12:23*am, Art Unwin wrote:

*What one gains from this aproach is that any radiator of any shape,
*size or elevation can provide figures in the order of 100% as long as
the radiator is a multiple of a wavelength where it is *resonant at
exact and repeatable measurements.

"Figures in the order or 100%" of what?

All radiators of all sizes and shapes will radiate on the order of
100% of all the r-f energy that can be coupled into them through their
input terminals, whether or not those conductor sizes/shapes are
naturally resonant at the applied frequency.

But the fact remains that natural resonance does not occur in
electrically small radiators -- while their radiation resistance is
very small, and their feedpoint is very reactive. *These realities
make it very difficult to supply r-f power to such a radiator without
relatively high losses.

As a consequence, the efficiency of the transmitter SYSTEM
(transmitter + radiator + matching network, + r-f ground loss in the
case of monopoles) can be very low.

To illustrate, the link below leads to a calculation of the
performance of a 3-meter monopole system on 1500 kHz. *Due to the low
radiation resistance and system losses, and even though the short
monopole itself is nearly 100% efficient at radiating the power across
its feedpoint, that radiator receives only about 0.37% of the power
available from the transmitter. *So the system efficiency is very
poor.

Such an electrically short radiator (no matter what its shape) is not
very useful compared to a naturally resonant 1/4-wave monopole or 1/2-
wave dipole -- both of which can radiate nearly

The use of the term "nearly" does not imply total accuracy.
To use Maxwell's equations for accuracy one cannot introduce metrics
that are not absolute.
1/4 or 1/2 wave radiators cannot supplant the "period" of a wave form
and thus introduce inaccuracies. The use of different algarithums in
programing accentuate or minimise the effect of these inaccuracies
thus providing different results. Same goes for close spaced wires
where the use of "near" accurate capacitances by avoidance of all
other proximety effects again take away from the accuracy of Maxwell's
equations. An accurate measurement of resonance of a mesh as I have
shown on my web page need not be dissed because of the presence of a
computer program.


100% of the available
power.

The calculations in the link below were made using standard equations,
in a spreadsheet format to make it easy to follow and confirm.
Properly constructed/used NEC models will verify the spreadsheet
calculation, and the statements about the dipoles mentioned above.

There is no cause to distrust NEC when it is properly understood and
properly used.

http://i62.photobucket.com/albums/h8...5on1500kHz.gif

RF

Art Unwin wrote:

What one gains from this aproach is that any radiator
of any shape, size or elevation can provide figures in
the order of 100% as long as the radiator is a multiple
of a wavelength where it is resonant at exact and
repeatable measurements.

then Art wrote:

The use of the term "nearly" does not imply total accuracy.

Note that your use of the phrase "in the order of" does not
imply total accuracy, either -- even for radiators meeting
your criteria.

To use Maxwell's equations for accuracy one cannot introduce
metrics that are not absolute. 1/4 or 1/2 wave radiators cannot
supplant the "period" of a wave form and thus introduce
inaccuracies.

Apparently you believe that only full-wave radiators are
"perfect" (exactly 100% efficient).

However a full-wave, center-fed dipole has a radiation resistance of
about 2,000 ohms, and a feedpoint reactance exceeding 1,000 ohms
(capacitive). That impedance would present a very high VSWR to a
normal transmitter unless some kind of matching network was used.

Even if there was no matching or transmission line loss (or r-f ground
loss in the case of a monopole), that full-wave radiator still would
not be 100% efficient because of the ohmic losses encountered by the r-
f current flowing along the radiating structure (NOT the radiation
resistance).

RF

On Nov 15, 12:29*pm, Richard Fry wrote:
Art Unwin wrote:
What one gains from this aproach is that any radiator
of any shape, size or elevation can provide figures in
the order of 100% as long as the radiator is a multiple
of a wavelength where it is resonant at exact and
repeatable measurements.
then Art wrote:
The use of the term "nearly" does not imply total accuracy.

Note that your use of the phrase "in the order of" does not
imply total accuracy, either -- even for radiators meeting
your criteria.

To use Maxwell's equations for accuracy one cannot introduce
metrics that are not absolute. 1/4 or 1/2 wave radiators cannot
supplant the "period" of a wave form and thus introduce
inaccuracies.

Apparently you believe that only full-wave radiators are
"perfect" (exactly 100% efficient).
Until antenna programs all of which are based om Maxwell's equations
provide accountability of all forces involved to provide the 100%
efficiency, as shown by the use of
full wave radiators I have no other choice. It is as the catholic
religeon teachings when it says "give me the child and I will give you
the man." Its equivalent in education is to believe
only what the professor tells you that is written in his books as it
is he who determines
who graduates or not. Many of the masters did not have a formal
education such as Greene who had to justify from first principles
himself to determine what was correct and what was not. After serving
most of your years in life by adhering to the books it make no sense
in changing from a follower to a reseacher when the past has satisfied
your need.
As with religeon faith will always overide the tenents of science,
more so as you get older.

However a full-wave, center-fed dipole has a radiation resistance of
about 2,000 ohms, and a feedpoint reactance exceeding 1,000 ohms
(capacitive). *That impedance would present a very high VSWR to a
normal transmitter unless some kind of matching network was used.

Even if there was no matching or transmission line loss (or r-f ground
loss in the case of a monopole), that full-wave radiator still would
not be 100% efficient because of the ohmic losses encountered by the r-
f current flowing along the radiating structure (NOT the radiation
resistance).

RF

On Nov 15, 1:23*am, Art Unwin wrote:
Cebic found when comparing different style programs that some behaved
well in certain circumstance where others did not. Yet all antenna
programs
are based on the use of Maxwells equations where all programs should
have the same results, after all Maxwells equations are exact and not
fudged. One of the reasons is that since Maxwells laws are exact
radiators used must be resonant at repeatable points designated as a
period.
* *Fact is that most users use fractional wavelength designs, usually
a half wavelength, that is not resonant at repeatable points where
the area around the datum line of a sine wave is never equal when
generated around a tank circuit.
* * The reason for this is "voltage over shoot" which gets smaller
with every cycle but never disappears. Thus when programs are used
based on fractional wavelength radiators the results will never show
100% accountability and in fact efficiencies derived will be in the
order of 92%!
* If the radiator is of a wavelength then one is not using a "fudge"
figure
in the calculations and *then becomes possible to attain total
accountability with efficiency of 100%. regardles of what type program
is used.
* *If one is to use exact equations, as are Maxwell equations, then
one must also use measurements that are also exact and repeatable and
that is definitely not fractional wavelengths!
*What one gains from this aproach is that any radiator of any shape,
*size or elevation can provide figures in the order of 100% as long as
the radiator is a multiple of a wavelength where it is *resonant at
exact and repeatable measurements.
If anybody can give pointers that refute the accuracy of the above I
would be very interested in hearing them

How about giving some pointers as to where you got this BS. Sounds
like you just made a bunch of stuff up.


Jimmie

On Nov 15, 3:44*pm, JIMMIE wrote:
On Nov 15, 1:23*am, Art Unwin wrote:



Cebic found when comparing different style programs that some behaved
well in certain circumstance where others did not. Yet all antenna
programs
are based on the use of Maxwells equations where all programs should
have the same results, after all Maxwells equations are exact and not
fudged. One of the reasons is that since Maxwells laws are exact
radiators used must be resonant at repeatable points designated as a
period.
* *Fact is that most users use fractional wavelength designs, usually
a half wavelength, that is not resonant at repeatable points where
the area around the datum line of a sine wave is never equal when
generated around a tank circuit.
* * The reason for this is "voltage over shoot" which gets smaller
with every cycle but never disappears. Thus when programs are used
based on fractional wavelength radiators the results will never show
100% accountability and in fact efficiencies derived will be in the
order of 92%!
* If the radiator is of a wavelength then one is not using a "fudge"
figure
in the calculations and *then becomes possible to attain total
accountability with efficiency of 100%. regardles of what type program
is used.
* *If one is to use exact equations, as are Maxwell equations, then
one must also use measurements that are also exact and repeatable and
that is definitely not fractional wavelengths!
*What one gains from this aproach is that any radiator of any shape,
*size or elevation can provide figures in the order of 100% as long as
the radiator is a multiple of a wavelength where it is *resonant at
exact and repeatable measurements.
If anybody can give pointers that refute the accuracy of the above I
would be very interested in hearing them

How about giving some pointers as to where you got this BS. Sounds
like you just made a bunch of stuff up.

Jimmie

No Jim. Ideas with what is presented to me in science, where such can
be obtained from first principles and with agreement with known LAWS
of science rather than various theories. In this case the aproach of
Gauss provided a mathematical connection to Maxwells equations which
by the use of antenna programs based on Maxwell only provide
accountability of all forces. This is easily proven when use of a
program that is optimized to account for all forces involved in
radiation such that the solution provided is termed 100% efficient as
opposed to planar or other designs that cannot achieve 100% efficiency
because of the non accountability of the recognition of "over shoot".
One always looks for 100% accountability of all forces such that 100%
efficiency is achieved.
If you are in the early stages of education it would be folly to bring
forth suggestions to the contrary of those presented in the books and
your professor since these are the standards against which determines
whether you graduate or not. Obviously this is not the time to debate
differences. As life proceedes one becomes comfortable with alignment
with ideas and teachings that conform with those around you because in
general your wages depend on it. Thus you are dealing with faith
regardless of the attainment via first principles that produce
conflict.
So yes, your only response to continue a science debate is to provide
counter proof from first principles that is available some where in a
book! Compared to that task it is so much more convenient to exit the
debate on a statement that does not require a proof. Thus anger comes
to the fore and debate or a thread comes to an end.
Cheers
Art

On Nov 15, 10:17*pm, Art Unwin wrote:

. Sounds like you just made a bunch of stuff up.

Jimmie

No Jim. Ideas with what is presented to me in science, where *such can be obtained from first principles and with agreement with known LAWS
of science rather than various theories.

Is scientific theory inferior to scientific laws?

On Nov 15, 9:34*pm, Bill wrote:
On Nov 15, 10:17*pm, Art Unwin wrote:

*. Sounds like you just made a bunch of stuff up.

Jimmie

No Jim. Ideas with what is presented to me in science, where *such can be obtained from first principles and with agreement with known LAWS
of science rather than various theories.

Is scientific theory inferior to scientific laws?

Yes