John Smith wrote:

A half wave DLM is one which consists of a 1/2 wavelength radiator ...
...

Change the above:

A half wave DLM is one which consists of a 1/2 ELECTRICAL wavelength
radiator ...

Regards,
JS

"John Smith" wrote
A half wave DLM is one which consists of a 1/2 wavelength radiator ...
google it; or, Vincents patent contains VERY complete data on the
construction of one--he tested it, also, at the Navy complex.
later...
A half wave DLM is one which consists of a 1/2 ELECTRICAL wavelength
radiator ...
________

I just looked at that patent, and saw nothing about that. I did see many
references to the need for a good r-f ground for the DLM.

As a variation, the patent describes putting two DLMs back to back to create
a dipole. Of course, that form is no longer a DLM, it is a loaded dipole.

Can you refer me to the page(s) of that patent that describe(s) what you are
writing about?

RF

Richard Fry wrote:

...
I just looked at that patent, and saw nothing about that. I did see
many references to the need for a good r-f ground for the DLM.

As a variation, the patent describes putting two DLMs back to back to
create a dipole. Of course, that form is no longer a DLM, it is a
loaded dipole.

Can you refer me to the page(s) of that patent that describe(s) what you
are writing about?

RF

Well, give me a bit, and remind me if I don't get back to you in a
couple of days ...

However, I have a 10m and a 20m 1/2-wave DLM I am using now, I
constructed them from the info. gleamed from the patent, conversation
with Vincent, web, ...

Hold on ... just overloaded after the holidays--except for quick
comments ...

Regards,
JS

On 26 Nov, 10:46, John Smith wrote:
Richard Fry wrote:

...

I just looked at that patent, and saw nothing about that. I did see
many references to the need for a good r-f ground for the DLM.

As a variation, the patent describes putting two DLMs back to back to
create a dipole. Of course, that form is no longer a DLM, it is a
loaded dipole.

Can you refer me to the page(s) of that patent that describe(s) what you
are writing about?

RF

Well, give me a bit, and remind me if I don't get back to you in a
couple of days ...

However, I have a 10m and a 20m 1/2-wave DLM I am using now, I
constructed them from the info. gleamed from the patent, conversation
with Vincent, web, ...

Hold on ... just overloaded after the holidays--except for quick
comments ...

Regards,
JS

The post that originated this thread stated that the antenna was
unbalanced and therefore should have a ground system.
Fry had some comments that were not related or in conflict
with what was stated, he just doesn't read to well.
Back to the originating post.The antenna is unbalanced but without a
connected ground system such that current will flow on the outside of
the coax braid. If this braid is buried this current will leak to the
ground(capacitive coupling). Question. At what distance does the coax
have to travel such that current on the outside does not exist?
Art

art wrote:

...
The post that originated this thread stated that the antenna was
unbalanced and therefore should have a ground system.
Fry had some comments that were not related or in conflict
with what was stated, he just doesn't read to well.
Back to the originating post.The antenna is unbalanced but without a
connected ground system such that current will flow on the outside of
the coax braid. If this braid is buried this current will leak to the
ground(capacitive coupling). Question. At what distance does the coax
have to travel such that current on the outside does not exist?
Art

I understand this Art. However, I am sure you won't mind a bit of side
conversation--don't mean to hijack your thread. ;-)

Regards,
JS

On Mon, 26 Nov 2007 11:06:29 -0800 (PST), art
wrote:

At what distance does the coax
have to travel such that current on the outside does not exist?

Hi Arthur,

According to Brown, Lewis, and Epstein's work, the currents absorbed
by ground dissipate radial wire current (what is flowing on the
exterior of a coax) in a very short interval.

However, just where it "does not exist" is like the problem you have
with skin effect. The current diminishes asymptotically towards zero,
but most would agree that the practical current is gone within less
than a quarter wave length. The convergence with the asymptote could
be described to be infinitely far away - especially when the current
levels induced in far receiver antennas is so miniscule in comparison
to the diminished radial currents (4,5 or 6 orders of magnitude?).

73's
Richard Clark, KB7QHC

Richard Fry wrote:

...
Can you refer me to the page(s) of that patent that describe(s) what you
are writing about?

RF

OK. Just quickly, so you don't think I am just attempting to "dust you
off."

This:

"Current profiles have been developed for various such embodiments of
1/2 wave and 5/8 wave distributed loaded monopole antennas. The
manipulation of helix length and inductance as well as the ratio of load
coil to helix inductance may achieve a wide variety of suitable antennas."

From he (beware line wrapping--it is a LONG URL!)

http://patft.uspto.gov/netacgi/nph-P...m+AND+monopole

Further, you know, Mr. Vincent is one nice guy, at least my
communications with him convinced me of such. He offered to send me a
CD with all pertinent data on it (one ham to another.)

I would encourage you to make direct contact with him, if the naysayers
haven't totally peeved him off, I'd venture to guess it would be quite
an enlightening and enjoyable interchange ...

Unfortunately, I don't remember how I got his email and didn't add it to
my address book, probably got it from somewhere on the universities site
.... this might be a place to start (and has a contact phone number--if
nothing else.) But, I am sure a search/email-inquiry to uri.edu would
bear fruit.

http://www.uri.edu/news/vincent/report05/


Regards,
JS

"art" wrote
The antenna is unbalanced but without a connected
ground system such that current will flow on the
outside of the coax braid.
______________

Following in its odd style is one of the many references in the DLM patent
to the need/use of a "connected ground system" for it.

QUOTE In this embodiment the antenna is shown grounded to earth through a
grounding rod, ground wire and connected to the base of the antenna and
electrically connected using a ground clamp. Radial wires extending above
ground or buried in the ground are electrically connected to the antenna
using the ground wire and the ground rod and extend from the antenna base
for a uniform distance but not limited to any specific length. END QUOTE.

So another one of your cherished beliefs is shown to be untrue.

RF

"John Smith" wrote
OK. Just quickly, so you don't think I am just attempting to "dust you
off." This:
"Current profiles have been developed for various such embodiments of 1/2
wave and 5/8 wave distributed loaded monopole antennas. The manipulation
of helix length and inductance as well as the ratio of load coil to helix
inductance may achieve a wide variety of suitable antennas."

Thanks, but a monopole of every electrical length is still a monopole, and
they ALL require a very good r-f ground or counterpoise for best
perfromance.

Further, you know, Mr. Vincent is one nice guy, at least my communications
with him convinced me of such. I would encourage you to make direct
contact with him, if the naysayers haven't totally peeved him off, I'd
venture to guess it would be quite an enlightening and enjoyable
interchange. Unfortunately, I don't remember
how I got his email and didn't add it to my address book, ...

Not to worry. Mr Vincent and I have exchanged comments already. I sent him
some NEC data and analysis which by his replies he did not appear to
understand. He seemed to think that I was trying to use NEC to analyze his
DLM designs -- saying that such was impossible.

But I wasn't attempting to do so. My NEC data only showed that his 3.5 MHz
standard DLM didn't perform very well as compared to a conventional
1/4-wave, unloaded monopole with a good r-f ground, and was about the equal
of a conventional monopole of the same physical height using the same r-f
ground -- which, of course, differs from his and the official URI test
report claims for the DLM.

RF

Richard Fry wrote:

...
Thanks, but a monopole of every electrical length is still a monopole, and
they ALL require a very good r-f ground or counterpoise for best
perfromance.

While your use of "best performance" may leave you wiggle room, however,
that statement is, for the most part, BULL PUCKY! 1/2 wave monopoles
have little dependence of a full counterpoise or ground for, at least,
acceptable performance. Anyone playing with them on wood/fiberglass
fresh water marine craft will have that realization and knowledge.

Not to worry. Mr Vincent and I have exchanged comments already. I sent him
some NEC data and analysis which by his replies he did not appear to
understand. He seemed to think that I was trying to use NEC to analyze his
DLM designs -- saying that such was impossible.

OH MY GAWD! Well then, you must forgive the man, he simply didn't
realize who he was dealing with!!! Krist, all he is surrounded by there
with is masters, doctorates, scholars, etc. He made the simple mistake
of NOT ignoring them and paying attention to your words of great wisdom
.... now let me see, what is your credentials--doctorate in amateur radio?


But I wasn't attempting to do so. My NEC data only showed that his 3.5 MHz
standard DLM didn't perform very well as compared to a conventional
1/4-wave, unloaded monopole with a good r-f ground, and was about the equal
of a conventional monopole of the same physical height using the same r-f
ground -- which, of course, differs from his and the official URI test
report claims for the DLM.

RF

I don't believe any of the modeling programs are "aware" of what
dynamics are causing the DLM to outperform expected/modeled results--or,
simply put, if all you can do is model and naysay--the antenna sucks.
Build one ACCORDING TO VINCENTS DATA and you will use it ... spacing
between coils is critical, values of the coils are critical, and the
ratio of inductance between coils is critical--by critical, I mean these
factors GREATLY depend on following Vincents design closely--the antenna
is HIGHLY SCALABLE, i.e. every aspect of a 1/2 wave is 2x that of a 1/4,
etc.

When I spoke to him, he was a bit "aggravated" by know-it-all-hams who
had personally attacked him--none of which had apparently built a
prototype first! When did you say you had spoken to Mr. Vincent? ROFLOL

Regards,
JS