Loading Coils; was : Vincent antenna
 

Richard Clark wrote:
On Sun, 02 Dec 2007 22:32:50 GMT, Cecil Moore
wrote:

In what, about 2-4 ns?
No, it increases the VF by roughly 2x in a typical coil.
Why don't you already know that fact?

So, 4-8 nS?

My experience in building coils for base or center loaded verticals was
different. The ratio was close to 1:1 at the base if the replaced
length was not long. The ratio approached 2:1 when the coil was moved
up the vertical, towards the center. It almost did not work if the
coil was moved to the tip of the antenna, or to better say, a coil added
to the tip of the antenna was not an effective way to lower the
resonant frequency.

73, Roger, W7WKB

Loading Coils; was : Vincent antenna
 

AI4QJ wrote:

"Cecil Moore" wrote in message
.net...
Ian White GM3SEK wrote:
My apologies to AI4QJ. He was talking about a parallel R-L circuit, and
my reply was about a series R-L circuit. Each of our statements was
correct in its own context.

Sorry, but your statement is still incorrect. In a
traveling-wave circuit, the current phase varies
every inch along the circuit path. If it didn't,
rhombic antennas wouldn't work.

First, in response to Cecil:

The behaviour of an antenna doesn't depend on how someone chooses to
classify it. You can apply a traveling-wave *model*, but that is merely
your choice of analysis method. It doesn't change anything about how the
antenna actually behaves.

The challenge for Cecil's model is to explain how the antenna does
behave. This cannot be done by reclassifying the type of antenna, or
reclassifying the type of current through the loading coil.

(And please don't drag in yet another irrelevancy about rhombic
antennas. It'll be photons and momentum next.)

AI4QJ continues:
Yes, the total current will have a phase angle somewhere between zero and
ninety degrees. The vector describing the current through the resistor will
be horizontal to the x-axis. The vector describing the current through the
coil will be perpendicular to the x a-xis. The sum of the currents going
into and out of the R-L network will be the vector sum of the R and X(L)
current vectors (Kirchoff's current law) whose magnitude will be the the
hypoteneuse of the triangle formed by R and X(L) sides with an angle
somewhere between zero and 90 degrees.

(My apologies for the wordiness)

No problem about that; we're all thinking out loud about a difficult
subject, so by all means do whatever it takes to get it right.

I think we are in agreement about the basics. One is the boundary
condition that, If the antenna is loaded at a single point by pure
inductance, then by definition there will be zero phase shift in the
current between its terminals.

Practical antennas move away from this boundary condition because the
inductor occupies an appreciable fraction of the physical length, and
begins to behave more like a short section of helically loaded antenna.
In this case we do expect a phase shift in current from end to end of
the inductor, accompanied by radiation from the inductor itself.
However, any valid explanation of practical loading coils must predict
zero phase shift for the boundary condition where the coil displays no
other properties except pure inductance.


--

73 from Ian GM3SEK 'In Practice' columnist for RadCom (RSGB)
http://www.ifwtech.co.uk/g3sek

Loading Coils; was : Vincent antenna
 

Roger wrote:

My experience in building coils for base or center loaded verticals was
different. The ratio was close to 1:1 at the base if the replaced
length was not long. The ratio approached 2:1 when the coil was moved
up the vertical, towards the center. It almost did not work if the
coil was moved to the tip of the antenna, or to better say, a coil added
to the tip of the antenna was not an effective way to lower the
resonant frequency.

73, Roger, W7WKB


This, I assume, was a 1/4 radiator?

Both 1/4 are 1/2?

Regards,
JS

Loading Coils; was : Vincent antenna
 

John Smith wrote:

This, I assume, was a 1/4 radiator?

Both 1/4 are 1/2?

Regards,
JS

are = and--of course ... what can I say, it is late, I am going to bed.

Regards,
JS

Loading Coils; was : Vincent antenna
 

On Dec 2, 10:45 pm, Richard Clark wrote:
On Sun, 02 Dec 2007 22:32:50 GMT, Cecil Moore
wrote:

In what, about 2-4 ns?

No, it increases the VF by roughly 2x in a typical coil.
Why don't you already know that fact?

So, 4-8 nS?

Don't be silly. It decreases the delay from about 50 ns to about 25 ns
in my 75m Texas Bugcatcher coil. The 2-4 ns figure is a wet dream.
--
73, Cecil, w5dxp.com

Loading Coils; was : Vincent antenna
 

On Dec 3, 12:55 am, K7ITM wrote:
Cecil Moore wrote:

In a traveling-wave environment, the phase changes
every inch around the circuit and I can calculate
that phase change...

OK, I live in a very cold environment (freespace) ...

No need for any esoteric stuff. A traveling wave changes one degree
every 1/360 of a cycle. That's just very elementary physics. If the
wavelength is 360 inches, a traveling wave changes one degree per
inch.
--
73, Cecil, w5dxp.com

Loading Coils; was : Vincent antenna
 

On Dec 3, 2:00 am, Ian White GM3SEK wrote:
The challenge for Cecil's model is to explain how the antenna does
behave. This cannot be done by reclassifying the type of antenna, or
reclassifying the type of current through the loading coil.

I'm not reclassifying anything. The differences between traveling-wave
antennas and standing-wave antennas have been known for many decades.
The problem that some of the gurus on this newsgroup have is that they
have forgotten everything they ever knew about standing-waves and
standing-wave antennas. You guys worship your shortcuts to such an
extent that you have completely lost touch with reality. W8JI's 3 ns
delay through a 100T coil on 4 MHz is just one example. At least a few
posters are beginning to understand why W8JI's measurement was
invalid.
--
73, Cecil, w5dxp.com

Loading Coils; was : Vincent antenna
 

AI4QJ wrote:
"Gene Fuller" wrote in message news:25J4j.191181
By the way, saying something is "impossible" is religion, not science. The
distance from one end of the coil to the other is clearly within reach
without violating the speed of light.

But not in 3 nsec. To go from one end to the other end of the 53 foot coil
would be to travel at 53.84E8 m/sec, more than 10 times the speed of light.



So you think an EM wave cannot travel 10 inches in 3 ns? Try again.

You appear to be suffering from the same disease that afflicts Cecil.
Plugging your preferred answer into the calculation might make the
solution easy, but it does not necessarily make it correct.

Since you seem to be somewhat oblivious to what is being debated, let me
restate it.

It is widely accepted that some configurations exhibit a "round and
round the wire mode." Helix antennas and traveling wave tubes fall into
that category.

It is also widely accepted that EM radiation is real, and travels the
speed of light in the appropriate medium.

It is also widely accepted that the "lumped circuit model" is useful in
many configurations.

The entire debate, if all of the personality nonsense is ignored, is
over the appropriate regimes for these "widely accepted" explanations.

Cecil insists that an 80 meter loading coil behaves nearly the same as
one of Corum's quarter-wave resonators. Others believe the coil behavior
is closer to a lumped circuit model.

Your assignment is to do the math to figure out just where in that
spectrum the truth lies.

Hint: "I lags V" is not helpful for the solution.

Good luck!

73,
Gene
W4SZ

Loading Coils; was : Vincent antenna
 

Cecil Moore wrote:
On Dec 3, 2:00 am, Ian White GM3SEK wrote:
The challenge for Cecil's model is to explain how the antenna does
behave. This cannot be done by reclassifying the type of antenna, or
reclassifying the type of current through the loading coil.

I'm not reclassifying anything. The differences between traveling-wave
antennas and standing-wave antennas have been known for many decades.

Oh good! Exactly where do *you* draw the line between them; and why?
Please justify this by giving examples of two antennas that are very
close to your chosen line, but on opposite sides.

Then please justify the difference between your two different
classifications of current.

The problem that some of the gurus on this newsgroup have is that they
have forgotten everything they ever knew about standing-waves and
standing-wave antennas. You guys worship your shortcuts to such an
extent that you have completely lost touch with reality. W8JI's 3 ns
delay through a 100T coil on 4 MHz is just one example. At least a few
posters are beginning to understand why W8JI's measurement was
invalid.

As you are so fond of saying, the technical content of that is duly
noted.


--

73 from Ian GM3SEK 'In Practice' columnist for RadCom (RSGB)
http://www.ifwtech.co.uk/g3sek

Loading Coils; was : Vincent antenna
 

On Dec 3, 7:40 am, Cecil Moore wrote:
On Dec 3, 12:55 am, K7ITM wrote:

Cecil Moore wrote:

In a traveling-wave environment, the phase changes
every inch around the circuit and I can calculate
that phase change...

OK, I live in a very cold environment (freespace) ...

No need for any esoteric stuff. A traveling wave changes one degree
every 1/360 of a cycle. That's just very elementary physics. If the
wavelength is 360 inches, a traveling wave changes one degree per
inch.
--
73, Cecil, w5dxp.com

What a disappointing non-answer, Cecil. I thought you said you can
calculate the phase change in a particular situation, and were willing
to do it. Is the description of the system lacking in some way?

Cheers,
Tom

Loading Coils; was : Vincent antenna
 

Gene Fuller wrote:

I know one should not respond to his own post, but I want to follow up
with one more thing.

As far as I can tell, W8JI did not do any math or other type of analysis
to come up with the 3 ns delay. There was some surrounding discussion,
but the delay itself was simply read from an instrument.

The 'number' is read from an instrument, but it isn't at all clear
what instrument is being read or what the number represents.

So let me repeat my earlier questions.

What went wrong? Why is that number incorrect?

I think we can assume the instrument is providing a correct indication
of something. But, given the documentation provided, it is not
possible to know whether it is a correct measurement of the
propagation delay of a device under test.

73, ac6xg

Loading Coils; was : Vincent antenna
 

On Mon, 3 Dec 2007 Cecil - through Ian - wrote:

At least a few
posters are beginning to understand why W8JI's measurement was
invalid.

"A few posters" necessarily renders them public figures (not anonymous
nor protected by the secrecy of email) who can be disclosed in this
side thread.

Simply name one other than Cecil (which would make it two, a minimum
"few") who finds the measurement INVALID!

Not valid is quite different from invalid.

Of course, no names will be named ("I have here in my pocket a list of
communists known to be serving in the State Department!" is a notable
quote from the history of the McCarthy era.) who won't immediately
take Cecil to task for his pimping them ("it is what they meant to say
if they really believe......").

This validity is again an illustration of deliberate, poor language
usage. Some may have found the measurement not valid (not enough
information to render that positive verdict) but none by my search of
973 prior postings reveals any that have found it invalid (rejected
because it is false).

As for myself, Tom attaching his assertion to his measurement reading
makes it improbable, but not invalid (and note, the negation of
invalid does not render it valid). As I've already gone on record
with responding to Dan's questions, I reserve judgment of its validity
pending further information - not that I expect any. Seeing that
Cecil wholeheartedly has yet to reveal the how (or data to the same
precision) of his own counter experiment (which I have also gone on
record in asking for details) - I don't expect anything there either.

If Cecil is to stand by his same standards of judgment he applies to
Tom, Cecil's assertion has already been found to be invalid also.

But then this has for years been a beauty contest for Cecil and his
tests of validity are as appropriate as are tests for virginity.

73's
Richard Clark, KB7QHC

Loading Coils; was : Vincent antenna
 

Richard Clark wrote:

"A few posters" necessarily renders them public figures (not anonymous
nor protected by the secrecy of email) who can be disclosed in this
side thread.

Simply name one other than Cecil (which would make it two, a minimum
"few") who finds the measurement INVALID!



So "Typically Richard."

Or, it is not what is said, it is who said it, simply put, "HERO
WORSHIP." Also akin to "religious doctrine", "all is known", "attacks
on personalities instead of principals", etc.

What a complete waste of text, bandwidth, patience, and time--you might
as well quote shakespeare in an antenna group! ROFLOL

Regards,
JS

Loading Coils; was : Vincent antenna
 

Gene Fuller wrote:
I don't believe anyone has actually challenged what Corum *says*. What
*has* been challenged is your misreading of the paper, especially the
required conditions for the validity of the analysis.

I very carefully applied the required conditions.
--
73, Cecil http://www.w5dxp.com

Loading Coils; was : Vincent antenna
 

Gene Fuller wrote:
Cecil Moore wrote:
A 10TPI, 2" dia., 100T coil used on 4 MHz is NOT an extreme
example. Why don't you just admit that you and W8JI have been
wrong for years and get it over with?

I never said that condition was extreme. Try the calculator at 40 kHz
and see what you get.

Uhhhhh Gene, changing the test frequency is an obvious
diversion of the issue, but knowing you, something that
is completely predictable.
--
73, Cecil http://www.w5dxp.com

Loading Coils; was : Vincent antenna
 

Gene Fuller wrote:
By the way, saying something is "impossible" is religion, not science.

Believing that impossible things are possible is the
*cornerstone of religion*. Let's see you rise from
the dead three days after your funeral.
--
73, Cecil http://www.w5dxp.com

Loading Coils; was : Vincent antenna
 

Cecil Moore wrote:
Gene Fuller wrote:
Cecil Moore wrote:
A 10TPI, 2" dia., 100T coil used on 4 MHz is NOT an extreme
example. Why don't you just admit that you and W8JI have been
wrong for years and get it over with?

I never said that condition was extreme. Try the calculator at 40 kHz
and see what you get.

Uhhhhh Gene, changing the test frequency is an obvious
diversion of the issue, but knowing you, something that
is completely predictable.

The lack of technical content of your post is duly noted.
73,
Tom Donaly, KA6RUH

Loading Coils; was : Vincent antenna
 

AI4QJ wrote:
With the coil in series with its internal resitance, the phase angle of the
current will be the same throughout all components in the circuit.

This is true for lumped circuits, not for distributed
networks.
--
73, Cecil http://www.w5dxp.com

Loading Coils; was : Vincent antenna
 

Owen Duffy wrote:
Then you are doing a lumped element approximation.

It is probably adequate for analysis of a short loading coil.

That is probably not a suitable method to analyse a helically loaded
monopole (where the monopole consists of nothing but a helix).

Not suitable either for a 160m mobile loading coil.
--
73, Cecil http://www.w5dxp.com

Loading Coils; was : Vincent antenna
 

Ian White GM3SEK wrote:
However, any valid explanation of practical loading coils must predict
zero phase shift for the boundary condition where the coil displays no
other properties except pure inductance.

Translation: A model must accommodate conditions that
are impossible to achieve in reality. I'm sorry, Ian,
but that is pathological thinking not uncommon on this
newsgroup.

A software model that blows up when R=0 is perfectly
acceptable in the real world. It is a software bug,
not a statement on reality.
--
73, Cecil http://www.w5dxp.com

Loading Coils; was : Vincent antenna
 

Cecil Moore wrote:
Gene Fuller wrote:
Cecil Moore wrote:
A 10TPI, 2" dia., 100T coil used on 4 MHz is NOT an extreme
example. Why don't you just admit that you and W8JI have been
wrong for years and get it over with?

I never said that condition was extreme. Try the calculator at 40 kHz
and see what you get.

Uhhhhh Gene, changing the test frequency is an obvious
diversion of the issue, but knowing you, something that
is completely predictable.

Cecil,

Are you so blinded by the battle that you cannot see anything else? I
was not talking about 80 meter loading coils. I was talking about the
overly broad application of the Corum model on that web page.

Go ahead, try any configuration you want. See if you agree with that web
calculator.

You are pretty clever, I must say. The king of the diversion accusing me
of diversion. I guess that any uncomfortable question is regarded by you
as a diversion, "something that is completely predictable."

73,
Gene
W4SZ

Loading Coils; was : Vincent antenna
 

Gene Fuller wrote:
So you think an EM wave cannot travel 10 inches in 3 ns? Try again.

Nice attempt at a diversion, Gene. What I said is that a
4 MHz EM wave cannot travel 10 inches in 3 ns through a
2" dia, 100 turn loading coil. If you disagree, please
feel free to prove me wrong.

Cecil insists that an 80 meter loading coil behaves nearly the same as
one of Corum's quarter-wave resonators. Others believe the coil behavior
is closer to a lumped circuit model.

The entire rest of the antenna is ten degrees. Why wouldn't
a 75m loading coil operate nearly the same as Corum's 1/4WL
resonators??? Are Maxwell's laws different for loaded mobile
antennas or for Corum's coils?
--
73, Cecil http://www.w5dxp.com

Loading Coils; was : Vincent antenna
 

On Mon, 03 Dec 2007 13:11:13 -0800, John Smith
wrote:

Simply name one other than Cecil (which would make it two, a minimum
"few") who finds the measurement INVALID!

So "Typically Richard."

OK, we've narrowed it down to both you and Cecil who cannot rummage up
a name in the list. And given you don't have a Chihuahua in this
fight, you can't even offer your own name - literally! :-0

73's
Richard Clark, KB7QHC

Loading Coils; was : Vincent antenna
 

On Mon, 03 Dec 2007 22:08:42 GMT, Gene Fuller
wrote:

Go ahead, try any configuration you want. See if you agree with that web
calculator.

C'mon Gene,

Drop the shoe. What is the result? I've lost track of the URL and
would like to hear the punchline. Cecil won't understand it anyway,
so what difference would it make?

73's
Richard Clark, KB7QHC

Loading Coils; was : Vincent antenna
 

On 3 Dec, 13:36, Cecil Moore wrote:
Gene Fuller wrote:
I don't believe anyone has actually challenged what Corum *says*. What
*has* been challenged is your misreading of the paper, especially the
required conditions for the validity of the analysis.

I very carefully applied the required conditions.
--
73, Cecil http://www.w5dxp.com

Cecil,
The bottom line of all this postulating is that YOU and only YOU were
visciferious about something being wrong with Tom and Roy's
experiment.
Whether you gave the correction in its propper fashion is of no
matter.
Thus a new old wifes tail was beaten down at the beginning, so
kudo's
to you while the others sulk.
Same thing happened to me with respect to adding time to both sides
of
the Gaussian equation where all ignored the fact that Dr Davis
provided the
mathematical proof. In both cases the group admitted no wrong but rest
assured
the flames will go on as if they were right and you were wrong.
This has happened many times before over the last decade with many
other gurus
who left rather than to descend to the level of the flame throwers.
W8TI left
for the same reasons but fortunately not away from the hobby itself.
One thing that does come out from this is that all is NOT known about
antennas despite the i9nsinuations of those who view themselves as
experts.
Every one of the pseudo experts on this group have been proved wrong
one
time or anather and yet they still flaunt themselves as experts.
It used to be that one should not just ask one expert but more than
one,
to which I add but none from this group.
Now every body, take a seat and watch Richard quote from McBeth
in a lovely white gown bought especially for the occasion.
Curtain up..Your cue Richerd/Lady Mc Beth....oh dear your
slip is showing once again.
Cecil move to the top of the table because YOU are worth the salt
while the present occupants can slink away while all observe
their embarisment
As I said ,
CURTAIN UP.....Lady McBeth, stage left,spotlight.
Mc Beth starts her weeping....
Art Unwin kb9mz....xg (UK)

Loading Coils; was : Vincent antenna
 

Ian White GM3SEK wrote:
Cecil Moore wrote:
I'm not reclassifying anything. The differences between traveling-wave
antennas and standing-wave antennas have been known for many decades.

Oh good! Exactly where do *you* draw the line between them; and why?
Please justify this by giving examples of two antennas that are very
close to your chosen line, but on opposite sides.

Glad to oblige. The two classical examples are a 1/2WL dipole
vs a terminated rhombic. The differences are obvious. The ends
of the standing-wave 1/2WL dipole are open-circuited so forward
waves undergo a total reflection. Ideally, the traveling-wave
rhombic is terminated in its characteristic impedance so
reflections are eliminated.

The equation for the current in a 1/2WL dipole is roughly
proportional to cos(x)*cos(wt). The equation for the current in
an ideal rhombic is proportional to cos(x+wt) where w=2*Pi*F.
For anyone with a math background, those differences are more
than obvious and I pointed that out years ago.

Then please justify the difference between your two different
classifications of current.

I don't have to justify that, Ian. Mathematics automatically
justifies it for me. If you would simply take the time to understand
the difference between cos(x)*cos(wt) and cos(x+wt), you would
understand it also.

The current in an ideal rhombic is 100% forward current proportional
to cos(x+wt). The current in a 1/2WL dipole is the sum of two
currents. The forward current is roughly proportional to cos(x+wt)
just as it is in the rhombic. The reflected current is roughly
proportional to cos(x-wt) and when those two traveling-wave currents
are added the resultant standing-wave current is proportional to
cos(x)*cos(wt), a completely different kind of current as is obvious
from their different equations.

The purists may take me to task for using a cosine function instead
of a sine function or using '+' for forward waves and '-' for
reflected waves but it doesn't change the conceptual conclusion.
Unfortunately, there is a difference in sign conventions between
optics and RF. Such mundane differences do not change the concepts
involved.
--
73, Cecil http://www.w5dxp.com

Loading Coils; was : Vincent antenna
 

K7ITM wrote:
I thought you said you can
calculate the phase change in a particular situation, and were willing
to do it. Is the description of the system lacking in some way?

I have no idea what "system" you are talking about.

It's not a rocket science concept, Tom. One degree of
an antenna causes a one degree shift in the phase of the
traveling waves. If you disagree, please enlighten us.
--
73, Cecil http://www.w5dxp.com

Loading Coils; was : Vincent antenna
 

Richard Clark wrote:
Not valid is quite different from invalid.

What is your native language? :-) From Webster's:
"in - a prefix ... having a negative force"

Seeing that
Cecil wholeheartedly has yet to reveal the how (or data to the same
precision) of his own counter experiment (which I have also gone on
record in asking for details) - I don't expect anything there either.

Good grief, Richard, I posted a detailed description of those
measurements more than a year ago before I moved to my new QTH.
In words, with a 50 ohm source, set up an autotransformer to
deliver a signal to a 3600 ohm Z0 environment. Put the 75m Texas
Bugcatcher coil in series with a 3600 ohm non-inductive load.
Measure the phase shift through the coil at 4 MHz. I eyeballed
it at ~25 degrees on a dual-trace 100 MHz O'scope.
--
73, Cecil http://www.w5dxp.com

Loading Coils; was : Vincent antenna
 

Tom Donaly wrote:
The lack of technical content of your post is duly noted.

The lack of technical content of your post is duly noted.
--
73, Cecil http://www.w5dxp.com

Loading Coils; was : Vincent antenna
 

Gene Fuller wrote:
Are you so blinded by the battle that you cannot see anything else? I
was not talking about 80 meter loading coils. I was talking about the
overly broad application of the Corum model on that web page.

Well, since the context is 80 meter bugcatcher loading coils,
I guess that's why I was confused.
--
73, Cecil http://www.w5dxp.com

Loading Coils; was : Vincent antenna
 

On Mon, 03 Dec 2007 23:23:45 GMT, Cecil Moore
wrote:

In words, with a 50 ohm source, set up an autotransformer to
deliver a signal to a 3600 ohm Z0 environment. Put the 75m Texas
Bugcatcher coil in series with a 3600 ohm non-inductive load.
Measure the phase shift through the coil at 4 MHz. I eyeballed
it at ~25 degrees on a dual-trace 100 MHz O'scope.

And what was it when you cut the coil in half?

Loading Coils; was : Vincent antenna
 

Cecil Moore wrote:

Richard Clark wrote:

Not valid is quite different from invalid.


What is your native language? :-) From Webster's:
"in - a prefix ... having a negative force"

If I've learned anything from you Cecil, it's that the writer gets to
choose which definition he tends, or intends, whatever the case may
be. Perhaps your emphasis is on the wrong syllable. :-)

73, ac6xg

Loading Coils; was : Vincent antenna
 

Richard Clark wrote:
Cecil Moore wrote:
In words, with a 50 ohm source, set up an autotransformer to
deliver a signal to a 3600 ohm Z0 environment. Put the 75m Texas
Bugcatcher coil in series with a 3600 ohm non-inductive load.
Measure the phase shift through the coil at 4 MHz. I eyeballed
it at ~25 degrees on a dual-trace 100 MHz O'scope.

And what was it when you cut the coil in half?

I apologize, Richard, like W8JI, I am unwilling to cut my
75m Texas bugcatcher coil in half. But then, his coil didn't
cost $180 either. :-)

The experiment that you are suggesting is exactly the same
that I suggested to W8JI but he was unwilling to perform
such and I tend to understood why. :-)

As a data point, in the previous argument a couple of years
ago, W8JI tried to use the lumped inductance feature of EZNEC
to "prove" there is never any phase shift through any coil. :-)
--
73, Cecil http://www.w5dxp.com

Vincent antenna
 

wrote in message
...
On Nov 27, 5:31 am, "Richard Fry" wrote:
"John Smith" wrote I don't believe any of the modeling programs are
"aware" of what dynamics
are causing the DLM to outperform expected/modeled results--

__________

Using Vincent's own numbers for the performance of a 3.5 MHz standard DLM
shows otherwise, and that doesn't necessarily take a modeling program to
discover.

As I stated in my last post in this thread, I was NOT using NEC to model
the
DLM in any form. I modeled a standard, base loaded monopole of the same
physical height as the 3.5 MHz DLM, and compared the NEC result for that
to
the DLM data in the URI test report, and the DLM data to the well-known
performance of a standard 1/4-wave monopole -- which performance has been
accurately measured.by broadcast stations thousands of times over the
last
70+ years.

That DLM system radiated only about 59% of the power applied to it, which
is
well below the ~95% radiated by a standard 1/4-wave monopole using a
"broadcast type" buried radial ground.

Check the numbers for yourself.

RF

It doesn't matter. He mounted one on his bike, and he can
make contacts, so all the rules go out the window... :/
What I'd still like to see is the reinvention compared against
a same height short monopole which is purely top hat loaded.
I bet the DLM reinvention loses a bit of it's gee whiz status...
If the DLM is all it's cracked up to be, the LW aircraft beacon
boys should all be switching over real soon..
I'm not going to hold my breath waiting.. :(
Using extended helical windings for short whips is nothing new
either.
The CB'ers have been doing it for years and years.
It's a valid concept which in *some* cases can give an
advantage, but it sure isn't anything new.
People whine that no one tries the DLM in the real world.
But I already tried my own versions of basically the same thing
many years ago. "for mobile use"
But I don't use any versions of that basic design any more because
it is proven inferior vs other more standard methods such as
top hat loading, or using a single large high Q loading coil
instead of a bunch of split narrow wound coils of lower Q and
higher overall loss.
I still stand by my previous statements that the DLM is not an
optimum design for a short vertical. It has various warts, which
I won't bother elaborating on.. There is not much point since it
will just fly off into space ignored by the usual DLM-Gaussian
campers.
MK

I concur with Mike, I was at Boxboro when Vincent made his presentation and
I also concluded that there were more fancy twists and words applied to this
design than any design tricks to make it another "miracle" antenna.
As far as Vincent goes, he is some maintenance man at UofRI, with no
involvement in any RF or Antenna labs or facilities there and PhD behind any
of his work, he simply works there and used U for PR noise.
One can paint loading coil or wire red and claim breakthrough in antenna
design and get a patent. Testing antennas over "perfect" navy ground will
make even coathanger look better.

Yuri K3BU.us

Loading Coils; was : Vincent antenna
 

Jim Kelley wrote:
If I've learned anything from you Cecil, it's that the writer gets to
choose which definition he tends, or intends, whatever the case may be.

Since I'm the one who used the word "invalid", to
which Richard objected, I am thrilled that you side
with me instead of him.
--
73, Cecil http://www.w5dxp.com

Loading Coils; was : Vincent antenna
 

On Dec 3, 3:08 pm, Cecil Moore wrote:
K7ITM wrote:
I thought you said you can
calculate the phase change in a particular situation, and were willing
to do it. Is the description of the system lacking in some way?

I have no idea what "system" you are talking about.

That's a continuing problem you have when you cut off the important
parts of postings you reply to. Though it's your problem, not mine,
I've obliged you by repeating the description at the bottom of this
posting.


It's not a rocket science concept, Tom. One degree of
an antenna causes a one degree shift in the phase of the
traveling waves. If you disagree, please enlighten us.
--
73, Cecil http://www.w5dxp.com

Cecil, I posed two very specific examples for you to work out to show
us that you can actually correctly find the phase shift for travelling
waves, as you promised you could and would. I would just like you to
deliver on your promise. The specifics are repeated below--though
you'd really help that short term memory loss thing if you would just
quote the whole posting you're replying to, instead of always cutting
off the meat. If you don't want to deliver, just say so and I'll
leave you alone.

"OK, I live in a very cold environment (freespace) and I've discovered
I can make and use high-temperature superconductors here, so I can
wind very small coils that still have high Q. In fact, the Q is
practically infinite, even for small coils. I've made a dipole from
0.1 inch diameter wire, 16 feet long total (192 inches). Four feet
from each end I've put a coil of about 390 turns (gets a bit hard to
keep track of the count) of very fine wire in a helix 0.1 inches
diameter and 0.2 inches long. This seems to give me resonance at
3.9MHz, though a rather nasty low feedpoint impedance. Master guru,
can you tell me please the travelling-wave phase change from one end
of one of those coils to the other end of the same coil, at 3.9MHz, in
the described environment? And can you tell me why I should care
about that?

"I'm also experimenting with capacitively loaded long antennas, and I
have another dipole that's 180 feet long, also made from 0.1" diameter
wire. I've put tiny capacitors 45 feet in (25% of the total length)
from each end, and adjusted them for resonance at 3.9MHz. This yields
a much easier to feed feedpoint impedance. They are, like the coils,
the same diameter as the wire, and about 0.04 inches long. Master
guru, can you tell me please the travelling-wave phase change from one
end of one of those capacitors to the other end of the same capacitor,
at 3.9MHz, in the described environment? And can you tell me why I
should care about that?

"(And how about trying to surprise us all, and quote and answer the
whole thing, not just some select part, huh?)"

Loading Coils; was : Vincent antenna
 

Richard Clark wrote in
:

On Mon, 03 Dec 2007 23:23:45 GMT, Cecil Moore
wrote:

In words, with a 50 ohm source, set up an autotransformer to
deliver a signal to a 3600 ohm Z0 environment. Put the 75m Texas

I can't see why an attempt to impedance match the source was necessary,
the reflection coefficient is determined solely by the load and line
characteristics.

Bugcatcher coil in series with a 3600 ohm non-inductive load.
Measure the phase shift through the coil at 4 MHz. I eyeballed
it at ~25 degrees on a dual-trace 100 MHz O'scope.

If you were confident that reflection was insignificant, then this test
design might properly reveal the one way delay of the transmission line
section.


And what was it when you cut the coil in half?


Sampling the forward wave (which should be the dominant wave if with an
approximatly matched load) at various points and comparing phase (wrt
source) with displacement might establish if the apparent phase velocity
is constant.

I don't suspect that the outcome of a properly designed and executed
experiment is going to surprise anyone.

Interesting as the answer is, the question still remains, what can one do
with the knowledge of the one way delay of a short loading coil when
designing a loaded monopole?

Owen

Loading Coils; was : Vincent antenna
 

K7ITM wrote:
Cecil, I posed two very specific examples for you to work out to show
us that you can actually correctly find the phase shift for travelling
waves, as you promised you could and would.

Sorry, Tom, when I came to the word "superconductor", I
stopped reading your posting. Please try to stick to
the real world of amateur radio next time. Anyone at
anytime can come up with some impossible esoteric
example that defies solution. Such examples are a
"vexations of the spirit" and I don't waste the
little time I have left on such nonsense. Please go
find another victim for your tarbaby.
--
73, Cecil http://www.w5dxp.com

Loading Coils; was : Vincent antenna
 

Cecil Moore wrote:


Please understand exactly what I am saying, Owen.

1. There is a *substantial* phase change in the *traveling-wave*
current along the coil. Traveling-wave current is hard to
measure in a standing-wave antenna but its phase yields
complete and accurate phase/delay information.

2. There is virtually *no* phase change in the *standing-wave*
current along the coil. Standing-wave current is easy to
measure in a standing-wave antenna but its phase yields
close to *zero phase/delay information*.

3. In a standing-wave antenna, the total current is primarily
standing-wave current. In a loaded mobile antenna, the standing-
wave current is approximately 90% of the total current thus
tending to mask the traveling-wave current.

Honestly, Cecil, it's pretty hard to know what you mean considering
the reckless way you throw around the term 'phase'. I'll grant that
you might know what you mean, but I don't see how you can expect
anyone else to.

73, ac6xg

Loading Coils; was : Vincent antenna
 

Owen Duffy wrote:
I can't see why an attempt to impedance match the source was necessary,
the reflection coefficient is determined solely by the load and line
characteristics.

This may (or may not) be a source of misunderstandings on this
newsgroup. If the source is not matched to the characteristic
impedance of the environment, then reflections result, even if
they are "same-cycle" reflections. That leads to such concepts
as unchanging phase all around the circuit in violation of the
rules for distributed networks.

Ask yourself this question: One inch away from a mismatched load
at HF frequencies, do reflections exist? If your answer is "no",
it is time to question your concepts. If your question is "yes",
then the same thing happens when the load is one inch away from
the source. Think about that.

If you were confident that reflection was insignificant, then this test
design might properly reveal the one way delay of the transmission line
section.

The goal in this type of measurement is to reduce the reflections
to a manageable level. If one recognizes what one is observing, one
can "see" the forward waves when the standing wave is half of
the total waveform. Ideally, the reflections would be eliminated,
but that is not an absolutely necessity.

I don't suspect that the outcome of a properly designed and executed
experiment is going to surprise anyone.

I can guarantee you it will be a total surprise to most of the
omniscient "gurus" on this newsgroup who will deny its validity.
If you side with the technical results of such an experiment, you
will be labeled a mentally disabled kook or worse.
--
73, Cecil http://www.w5dxp.com