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