Some care must be exercised to see that causality has not been violated: the
'July 9' date is a typo. The right date is, of course, 9 June.

I continue to get many e-mails asking for info about DLM designs. You will,
perhaps note, that the 7 June EE times article was AGAIN run--with
additions--on 14 June:

http://www.eet.com/showArticle.jhtml?articleID=21600147.

Mr. Vincent describes a design that, apparently, is well within the
description I discussed below on 11 June--at least that is my opinion.

As I have not seen Mr. Vincent's design, it would appear that said design is
either 'obvious to those skilled in the art', or not novel in some basic way,
again, an opinion. I will be most interested to see what true novelty is
ascribed and approved as the 'revolution' moves forward.

Incidentally, Mr. Vincent again ascribes his design as "wide in bandwidth" yet
describes substantial harmonic suppression. 'Wideband' designs are almost
always big enough in passband to cover the lowest end and its harmonics.

73,
Chip N1IR
---------------------------------------------------

Temat: DLM Antenna
Od: (Fractenna)
Grupa: rec.radio.amateur.antenna
Organizacja: AOL http://www.aol.com
Data: Jun 11 2004 12:29:42


--------------------------------------------------------------------------
------


Hello--

I've received about 2 dozen e-mails on this subject. Prior to this, I
communicated with Mr. Vincent early on 9 July(SIC) and offered him the
opportunity
for scientific and objective independent testing. He declined due to a test
already ongoing at a facility that I feel is also capable of such testing (you
may ask Mr. Vincent if you wish).

My scientific interest in this topic is exhausted. I pose the following for
those interested in what is possible, and what has been done, along the lines
of distributed loading of helix monopoles. I invite you to investigate the
prior art for yourself.

I have not seen Mr. Vincent's design, but based upon his PR statements, it
appears to be a loaded helix monopole with a CCD-like arrangement for
neutralization. The design, of course, may be different and novel, although I
am not of that opinion, based upon the 3 reports published in the popular
press. In the absence of knowledge, it is impossible to fully assess. Still,
there is value in knowing what has been done and what is possible.

----------------------------------------

The prior art is rife with distributed loading of monopoles to extensively
shorten them.

Here is a prior art method that will gives a few percent bandwidth and about -2
dBd for less than 1/15 wave height. I invite you to experiment for values and
placements:

* Take a half wave of wire (approximately);
* Wind it into a helix of about 10^-3 waves diameter (or less);
* Place an inductive load half way up;
* Add at least 2 and up to 6 capacitors at distributed points along the helix
length;
* If you wish to truncate the current at the top, then add a small end cap hat;

Essentially this is a shrunken 1 wave dipole manifest as a 1/2 wave monopole,
using CCD (distributed capacitors) to neutralize the inductance. (remember:
not all cacapcitors need be discrete components ). Helical designs originated
with Harold Wheeler more than 50 years ago. CCD articles have predominantly
appeared in ham magazines in the 70's and 80's, although the original invention
is (I believe) British and over 40 years old. There are many relevant patents,
all expired to my knowledge.

This design approach will 'linearize' the current (slow he wave) and do a
pretty good job. A shrunken 1/2 wave monopole does better than a shrunken 1/4
monopole. When you compare it to a full-sized 1/4 wave monopole it will do well
at a specific frequency.

It is an interesting question whether the relevant comparison should be to a
1/4 wave monopole or a 1/2 wave monopole. Such shrunken designs are 1/2 wave
equivalents, not 1/4 wave equivalents. They will look much worse in performance
compared to full sized counterparts. A 1/4 wave monopole is not a counterpart,
although in a practical sense it is a much used antenna which one might seek to
replace and thus compare to.

HOWEVER for such a shrunken design--

* It will be moderate to narrow band;
* It will trade gain for efficiency and is NOT efficient;
* It will run hot in continuous-on applications with moderate to high power.

Gain is not efficiency. Sometimes efficiency doesn't matter, but gain does.
Other times the heating from inefficiency will kill an otherwise elegant design
option.

Mr. Vincent's original PR claims, to my recollection: high efficiency; good
(broad) bandwidth; very low height.

These are not mutually, physically, attainable. I, and many others, have spent
enough time to know. There is no reason to believe that Mr. Vincent has
attained these. What he has appeared to have attained, to my limited knowledge
based on published PR, is: moderate to low efficiency; modest bandwidth, and
very low height. To my knowledge, Mr. Vincent has neither done an efficiency
test nor a heating test.

In terms of applications, there are very few, besides some 'ham' and CB needs,
where a single band, somewhat inefficient whip is desired. Midland has a nice
compromise stick for CB'ers that's using some of these ideas and is two feet
high. I like their design.

--Using a heavily shortened CCD type helix monopole in a broadcast app will
lead to a fire. It is not highly efficient and the wasted power will manifest
as heat. As little as 30 watts of heat in a confined area will start a fire or
melt components if not properly dissipated. About a 1 dB loss to heat for 1000
watts power will produce well over 100 watts dissipated heat. Ergo, even a
reasonably efficient antenna is potentially dangerous if high power is used
and the heat is not properly dissipated. Mr. Vincent's design PR describes
melted components in some of his design efforts. This indicates inefficiency in
the design tested.

--Much of the world wants 'ground independent' antennas--not monopoles

-- Microwave applications are not single frequency, with few exceptions. Even
PIFA (inverted F) solutions--which are extremely low height, lower than Mr
Vincen'ts-- are multibanded.

--Much of the world wants multiband antennas, or wideband antennas, not modest
passbands.


73,
Chip N1IR

Fractenna wrote:
Some care must be exercised to see that causality has not been violated: the
'July 9' date is a typo. The right date is, of course, 9 June.

I continue to get many e-mails asking for info about DLM designs. You will,
perhaps note, that the 7 June EE times article was AGAIN run--with
additions--on 14 June:

http://www.eet.com/showArticle.jhtml?articleID=21600147.

Mr. Vincent describes a design that, apparently, is well within the
description I discussed below on 11 June--at least that is my opinion.

As I have not seen Mr. Vincent's design, it would appear that said design is
either 'obvious to those skilled in the art', or not novel in some basic way,
again, an opinion. I will be most interested to see what true novelty is
ascribed and approved as the 'revolution' moves forward.

Incidentally, Mr. Vincent again ascribes his design as "wide in bandwidth" yet
describes substantial harmonic suppression. 'Wideband' designs are almost
always big enough in passband to cover the lowest end and its harmonics.

73,
Chip N1IR
---------------------------------------------------

Temat: DLM Antenna
Od: (Fractenna)
Grupa: rec.radio.amateur.antenna
Organizacja: AOL http://www.aol.com
Data: Jun 11 2004 12:29:42


--------------------------------------------------------------------------
------


Hello--

I've received about 2 dozen e-mails on this subject. Prior to this, I
communicated with Mr. Vincent early on 9 July(SIC) and offered him the
opportunity
for scientific and objective independent testing. He declined due to a test
already ongoing at a facility that I feel is also capable of such testing (you
may ask Mr. Vincent if you wish).

My scientific interest in this topic is exhausted. I pose the following for
those interested in what is possible, and what has been done, along the lines
of distributed loading of helix monopoles. I invite you to investigate the
prior art for yourself.

I have not seen Mr. Vincent's design, but based upon his PR statements, it
appears to be a loaded helix monopole with a CCD-like arrangement for
neutralization. The design, of course, may be different and novel, although I
am not of that opinion, based upon the 3 reports published in the popular
press. In the absence of knowledge, it is impossible to fully assess. Still,
there is value in knowing what has been done and what is possible.

----------------------------------------

The prior art is rife with distributed loading of monopoles to extensively
shorten them.

Here is a prior art method that will gives a few percent bandwidth and about -2
dBd for less than 1/15 wave height. I invite you to experiment for values and
placements:

* Take a half wave of wire (approximately);
* Wind it into a helix of about 10^-3 waves diameter (or less);
* Place an inductive load half way up;
* Add at least 2 and up to 6 capacitors at distributed points along the helix
length;
* If you wish to truncate the current at the top, then add a small end cap hat;

Essentially this is a shrunken 1 wave dipole manifest as a 1/2 wave monopole,
using CCD (distributed capacitors) to neutralize the inductance. (remember:
not all cacapcitors need be discrete components ). Helical designs originated
with Harold Wheeler more than 50 years ago. CCD articles have predominantly
appeared in ham magazines in the 70's and 80's, although the original invention
is (I believe) British and over 40 years old. There are many relevant patents,
all expired to my knowledge.

This design approach will 'linearize' the current (slow he wave) and do a
pretty good job. A shrunken 1/2 wave monopole does better than a shrunken 1/4
monopole. When you compare it to a full-sized 1/4 wave monopole it will do well
at a specific frequency.

It is an interesting question whether the relevant comparison should be to a
1/4 wave monopole or a 1/2 wave monopole. Such shrunken designs are 1/2 wave
equivalents, not 1/4 wave equivalents. They will look much worse in performance
compared to full sized counterparts. A 1/4 wave monopole is not a counterpart,
although in a practical sense it is a much used antenna which one might seek to
replace and thus compare to.

HOWEVER for such a shrunken design--

* It will be moderate to narrow band;
* It will trade gain for efficiency and is NOT efficient;
* It will run hot in continuous-on applications with moderate to high power.

Gain is not efficiency. Sometimes efficiency doesn't matter, but gain does.
Other times the heating from inefficiency will kill an otherwise elegant design
option.

Mr. Vincent's original PR claims, to my recollection: high efficiency; good
(broad) bandwidth; very low height.

These are not mutually, physically, attainable. I, and many others, have spent
enough time to know. There is no reason to believe that Mr. Vincent has
attained these. What he has appeared to have attained, to my limited knowledge
based on published PR, is: moderate to low efficiency; modest bandwidth, and
very low height. To my knowledge, Mr. Vincent has neither done an efficiency
test nor a heating test.

In terms of applications, there are very few, besides some 'ham' and CB needs,
where a single band, somewhat inefficient whip is desired. Midland has a nice
compromise stick for CB'ers that's using some of these ideas and is two feet
high. I like their design.

--Using a heavily shortened CCD type helix monopole in a broadcast app will
lead to a fire. It is not highly efficient and the wasted power will manifest
as heat. As little as 30 watts of heat in a confined area will start a fire or
melt components if not properly dissipated. About a 1 dB loss to heat for 1000
watts power will produce well over 100 watts dissipated heat. Ergo, even a
reasonably efficient antenna is potentially dangerous if high power is used
and the heat is not properly dissipated. Mr. Vincent's design PR describes
melted components in some of his design efforts. This indicates inefficiency in
the design tested.

--Much of the world wants 'ground independent' antennas--not monopoles

-- Microwave applications are not single frequency, with few exceptions. Even
PIFA (inverted F) solutions--which are extremely low height, lower than Mr
Vincen'ts-- are multibanded.

--Much of the world wants multiband antennas, or wideband antennas, not modest
passbands.



What I have become stuck on is the claim of constant current along the
length of the antenna - or 80 percent as claimed. How does this work? I
don't profess to know much about these matters, but if the current stays
the same, then the voltage must too?

And i still can't figure out how such an efficient antenna "melts". 8^)

- Mike KB3EIA -

Mike wrote,


What I have become stuck on is the claim of constant current along the
length of the antenna - or 80 percent as claimed. How does this work? I
don't profess to know much about these matters, but if the current stays
the same, then the voltage must too?

And i still can't figure out how such an efficient antenna "melts". 8^)

- Mike KB3EIA -


Anyone can make a "constant current" dipole, just by making it small
enough in relation to the wavelength of the frequency it's to be used for.
Of course, as has been pointed out here many times, feeding such an antenna
would be difficult to impossible, and bandwidth would be small, but you can't
have
everything.
Some theorists in the late 1940's did some work on the fundamental limits of

small antennas. There are one or two papers available on the web if you search

for "small antennas" with google. People who think they can make a small (in
terms of
a wavelength) single radiator antenna, with good efficiency, and a large
bandwidth,
that doesn't have to resort to feedline radiation to achieve its aims,
would do well to read these papers before making themselves look silly by
claiming
the impossible.
73,
Tom Donaly, KA6RUH

What I have become stuck on is the claim of constant current along the
length of the antenna - or 80 percent as claimed. How does this work? I
don't profess to know much about these matters, but if the current stays
the same, then the voltage must too?

And i still can't figure out how such an efficient antenna "melts". 8^)

- Mike KB3EIA -




If they believe W8JI et al claim that current through the loading coil is
constant, then they would claim that they made the current constant. More on
the subject check
http://www.k3bu.us/loadingcoils.htm

Yuri, K3BU.us

Tom, I wouldn't be so quick in using the term " impossible" if I were
you until the facts come out. He has already stated that he has a
distributed load antenna which he referres to as a two dimensional
helix, which I see as a meander line on a circuit board. This
ofcourse, provides an antenna of very small size which has some
drawbacks. But the inventor states that the design is a combination of
known ideas which may well be a method of overcomming initial
drawbacks. After all a University have placed themselves behind the
inventor and most of us did not go to University on a platform of
disbelieving our professors . Even if it all turns out to be a
mistaken idea the majority of hams will learn from future interchange
rather than tagging along with those who believe all is already
known.Usually the best inventions are an amaqlgamation of all the good
observations noted in otherwise bad ideas/inventions made by somebody
who looks for every morsel that is new and is
resourceful enough to connect the dots before it becomes obvious to
the followers.It is rare that someting that comes along is totally new
in its entirety.
Regards
Art





(Tdonaly) wrote in message ...
Mike wrote,


What I have become stuck on is the claim of constant current along the
length of the antenna - or 80 percent as claimed. How does this work? I
don't profess to know much about these matters, but if the current stays
the same, then the voltage must too?

And i still can't figure out how such an efficient antenna "melts". 8^)

- Mike KB3EIA -


Anyone can make a "constant current" dipole, just by making it small
enough in relation to the wavelength of the frequency it's to be used for.
Of course, as has been pointed out here many times, feeding such an antenna
would be difficult to impossible, and bandwidth would be small, but you can't
have
everything.
Some theorists in the late 1940's did some work on the fundamental limits of

small antennas. There are one or two papers available on the web if you search

for "small antennas" with google. People who think they can make a small (in
terms of
a wavelength) single radiator antenna, with good efficiency, and a large
bandwidth,
that doesn't have to resort to feedline radiation to achieve its aims,
would do well to read these papers before making themselves look silly by
claiming
the impossible.
73,
Tom Donaly, KA6RUH

Tom, I wouldn't be so quick in using the term " impossible" if I were
you until the facts come out. He has already stated that he has a
distributed load antenna which he referres to as a two dimensional
helix, which I see as a meander line on a circuit board. This
ofcourse, provides an antenna of very small size which has some
drawbacks. But the inventor states that the design is a combination of
known ideas which may well be a method of overcomming initial
drawbacks. After all a University have placed themselves behind the
inventor and most of us did not go to University on a platform of
disbelieving our professors . Even if it all turns out to be a
mistaken idea the majority of hams will learn from future interchange
rather than tagging along with those who believe all is already
known.Usually the best inventions are an amaqlgamation of all the good
observations noted in otherwise bad ideas/inventions made by somebody
who looks for every morsel that is new and is
resourceful enough to connect the dots before it becomes obvious to
the followers.It is rare that someting that comes along is totally new
in its entirety.
Regards
Art





(Tdonaly) wrote in message ...
Mike wrote,


What I have become stuck on is the claim of constant current along the
length of the antenna - or 80 percent as claimed. How does this work? I
don't profess to know much about these matters, but if the current stays
the same, then the voltage must too?

And i still can't figure out how such an efficient antenna "melts". 8^)

- Mike KB3EIA -


Anyone can make a "constant current" dipole, just by making it small
enough in relation to the wavelength of the frequency it's to be used for.
Of course, as has been pointed out here many times, feeding such an antenna
would be difficult to impossible, and bandwidth would be small, but you can't
have
everything.
Some theorists in the late 1940's did some work on the fundamental limits of

small antennas. There are one or two papers available on the web if you search

for "small antennas" with google. People who think they can make a small (in
terms of
a wavelength) single radiator antenna, with good efficiency, and a large
bandwidth,
that doesn't have to resort to feedline radiation to achieve its aims,
would do well to read these papers before making themselves look silly by
claiming
the impossible.
73,
Tom Donaly, KA6RUH

Tom, I wouldn't be so quick in using the term " impossible" if I were
you until the facts come out. He has already stated that he has a
distributed load antenna which he referres to as a two dimensional
helix, which I see as a meander line on a circuit board. This
ofcourse, provides an antenna of very small size which has some
drawbacks. But the inventor states that the design is a combination of
known ideas which may well be a method of overcomming initial
drawbacks. After all a University have placed themselves behind the
inventor and most of us did not go to University on a platform of
disbelieving our professors . Even if it all turns out to be a
mistaken idea the majority of hams will learn from future interchange
rather than tagging along with those who believe all is already
known.Usually the best inventions are an amaqlgamation of all the good
observations noted in otherwise bad ideas/inventions made by somebody
who looks for every morsel that is new and is
resourceful enough to connect the dots before it becomes obvious to
the followers.It is rare that someting that comes along is totally new
in its entirety.
Regards
Art





(Tdonaly) wrote in message ...
Mike wrote,


What I have become stuck on is the claim of constant current along the
length of the antenna - or 80 percent as claimed. How does this work? I
don't profess to know much about these matters, but if the current stays
the same, then the voltage must too?

And i still can't figure out how such an efficient antenna "melts". 8^)

- Mike KB3EIA -


Anyone can make a "constant current" dipole, just by making it small
enough in relation to the wavelength of the frequency it's to be used for.
Of course, as has been pointed out here many times, feeding such an antenna
would be difficult to impossible, and bandwidth would be small, but you can't
have
everything.
Some theorists in the late 1940's did some work on the fundamental limits of

small antennas. There are one or two papers available on the web if you search

for "small antennas" with google. People who think they can make a small (in
terms of
a wavelength) single radiator antenna, with good efficiency, and a large
bandwidth,
that doesn't have to resort to feedline radiation to achieve its aims,
would do well to read these papers before making themselves look silly by
claiming
the impossible.
73,
Tom Donaly, KA6RUH

Yuri Blanarovich wrote:
What I have become stuck on is the claim of constant current along the
length of the antenna - or 80 percent as claimed. How does this work? I
don't profess to know much about these matters, but if the current stays
the same, then the voltage must too?

And i still can't figure out how such an efficient antenna "melts". 8^)

- Mike KB3EIA -





If they believe W8JI et al claim that current through the loading coil is
constant, then they would claim that they made the current constant. More on
the subject check
http://www.k3bu.us/loadingcoils.htm


That work seems about right to me!

- Mike KB3EIA

Yuri Blanarovich wrote:
What I have become stuck on is the claim of constant current along the
length of the antenna - or 80 percent as claimed. How does this work? I
don't profess to know much about these matters, but if the current stays
the same, then the voltage must too?

And i still can't figure out how such an efficient antenna "melts". 8^)

- Mike KB3EIA -





If they believe W8JI et al claim that current through the loading coil is
constant, then they would claim that they made the current constant. More on
the subject check
http://www.k3bu.us/loadingcoils.htm


That work seems about right to me!

- Mike KB3EIA

Art wrote,

Tom, I wouldn't be so quick in using the term " impossible" if I were
you until the facts come out. He has already stated that he has a
distributed load antenna which he referres to as a two dimensional
helix, which I see as a meander line on a circuit board. This
ofcourse, provides an antenna of very small size which has some
drawbacks. But the inventor states that the design is a combination of
known ideas which may well be a method of overcomming initial
drawbacks. After all a University have placed themselves behind the
inventor and most of us did not go to University on a platform of
disbelieving our professors . Even if it all turns out to be a
mistaken idea the majority of hams will learn from future interchange
rather than tagging along with those who believe all is already
known.Usually the best inventions are an amaqlgamation of all the good
observations noted in otherwise bad ideas/inventions made by somebody
who looks for every morsel that is new and is
resourceful enough to connect the dots before it becomes obvious to
the followers.It is rare that someting that comes along is totally new
in its entirety.
Regards
Art


Hi Art,
he may very well have produced an antenna that works as
advertised. Time will tell. However, in evaluating the claims of anyone
who invents something new it is always advisable to compare those claims with
current theory before accepting them wholeheartedly. It isn't impossible to
make a small, useful, antenna - the small-in-terms-of-wavelength loop
is a case in point - but to make a small antenna with all the characteristics
of a large antenna strains the credibility. It sounds as if this gentleman
is trying to take advantage of the properties of the double-tuned circuit in
order to achieve a larger bandwidth while maintaining good efficiency.
If so, it's an interesting idea and I hope it works, but I'm not going to
get excited about it until I know more, such as, what happens to
the radiation pattern when the current in the top part of the
antenna is out of phase with the current in the bottom
part? Does it then radiate straight up, or does he have some
method of controlling the phase so it doesn't do this?
73,
Tom Donaly, KA6RUH