There was a report in the Electronic Engineering Times (16 May 05)
about this antenna, which is a helical with extra top-loading and an
optional capacitive hat. Designer was Rob Vincent (call?) at the
University of Rhode Island. More info at:
http://www.uri.edu/news/releases/index.php?id=3126
and a presentation at:
http://www.uri.edu/news/vincent/boxboro_files/frame.htm

Anyone seen this particular combination? Appears to have very good
performance.

Regards,
Allen WA0OHE
--
Allen Windhorn (507) 345-2782 FAX (507) 345-2805
Kato Engineering (Though I do not speak for Kato)
P.O. Box 8447, N. Mankato, MN 56002

On 23 May 2005 14:27:05 -0500, Allen Windhorn
wrote:

Anyone seen this particular combination? Appears to have very good
performance.

Hi Allan,

Alas, yes, and nothing seems to have improved over the months - same
spelling errors, lax reporting, sloppy presentation, and a smattering
of conflicting claims:
"Vincent’s Plano Spiral Top Hat antenna at 7 megahertz is half the
size of a normal quarter-wave antenna operating at that frequency.
:Note it says half the size, later this will be changed
The URI antenna gain matched the performance of the ideal
quarter-wave antenna, and its bandwidth was nearly twice as wide.
:as usual, no specifics offered, later this "twice" will be changed.
...
"In addition, the gain of Vincent’s capacity Top Hat DLM antenna,
:in addition to WHAT?
which incorporates a helix, a load coil, a capacitive top hat
:it incorporates 3 items? or 2? Is the helix the coil? More change follows.
utilizing radial spokes at the top of the antenna and a horizontal
plane was nearly identical to the ideal quarter wave antenna. Its
bandwidth was greater than 5 percent of the operating frequency
:not twice the bandwidth anymore (and not even close to standard BW)
and the antenna is more than 70 percent shorter than an ideal
quarter wave antenna.
:not half size - 30% size, but this changes again.

"Vincent’s standard DLM antennas with a standard helix and load
coil were also tested at various frequencies. All exhibited gains
:it incorporates 2 items? Standard helix is the former coil above?
nearly equal to the ideal antenna with bandwidths of 3 to 10
:well, what exactly is being compared to here? Ideal is 3? or is it 10?
percent. The antennas were 33 to 40 percent shorter."
:now we are LARGER than half size

Let's see, we have a 30%, half size, 67% tall radiator with 3 (make
that 2) loads that matches (nearly) the gain performance of a standard
antenna exhibiting somewhere between 3% and 10% bandwidth.

I note that the link (sic, the poor html authoring makes this simply a
text inclusion) to the Navy test site is NOT to the Navy Test Report,
but simply to the Navy test site (even the cfa web pages can produce a
link like that).

Tedious puffery at best.

73's
Richard Clark, KB7QHC

Richard Clark writes:

On 23 May 2005 14:27:05 -0500, Allen Windhorn
wrote:
...
Alas, yes, and nothing seems to have improved over the months - same
spelling errors, lax reporting, sloppy presentation, and a smattering
of conflicting claims...

Let's see, we have a 30%, half size, 67% tall radiator with 3 (make
that 2) loads that matches (nearly) the gain performance of a standard
antenna exhibiting somewhere between 3% and 10% bandwidth...

The presentation at the URI website has a lot more details --
apparently a number of antennas have been tested in various
configurations. (It still has spelling errors!)

The helix is the main part of the antenna, with a (maybe optional)
loading coil above that, then an optional straight section or top-hat,
which may or may not be spiral-wound to act as additional loading
coil. Reminds me of the "discpole" antenna in that it tries to get
uniform current in the radiating section.

Maybe I'll to build one to try it out.

73,
Allen WA0OHE
--
Allen Windhorn (507) 345-2782 FAX (507) 345-2805
Kato Engineering (Though I do not speak for Kato)
P.O. Box 8447, N. Mankato, MN 56002

On 23 May 2005 16:55:58 -0500, Allen Windhorn
wrote:

The presentation at the URI website has a lot more details --
apparently a number of antennas have been tested in various
configurations. (It still has spelling errors!)

Hi Allen,

Same old stuff. What I chose to criticize specifically did not mean I
was unaware of other problems of reporting and presentation. Given
the increased general incidence of spelling problems, some use that to
"prove" their passion as a substitute for their showing accuracy.
Without stigmata, it isn't so compelling.

Maybe I'll to build one to try it out.

When the world is clamoring for fractals, ehs, cfas, and lattins? Oh
well, ANY one of these built successfully (according to claim) would
be a first for the record book.

73's
Richard Clark, KB7QHC