On Oct 20, 11:34 am, "Mike Kaliski" wrote:


I agree. Incidently the origin of the idea for fractal antennae apparently
arose from the observation that hanging down the ends of a dipole, or
bending it to fit a limited site didn't affect the efficiency too much. A
university student decided to see just how much bending and could take place
before the antenna became unusable and hey presto, the fractal antenna was
invented and he had a thesis for his degree.

Mike G0ULI

Just linear loading with a fancy name..
Or the way I see it anyway..
The thing is... Most consider linear loading as
inferior to high Q coil loading, as long as the
coils are placed at the proper locations to
maximize current distribution.
But I can see their use in small items like
cell phones, etc..
I doubt if I would use one as a ham radio antenna
though.
Heck, my 160m "Z" dipole could be considered a
fractal. Even a dipole qualifies. All symmetrical
antennas can be called "fractals" if you wanted to
be strict about it.
MK

wrote:
Heck, my 160m "Z" dipole could be considered a
fractal. Even a dipole qualifies.

Yep, fractal stands for "fractional dimensions". A
dipole is primarily in one dimension. A "ground
plane" is primarily in two dimensions. Anything
that does not occupy all three dimensions equally
qualifies as a fractal.
--
73, Cecil http://www.w5dxp.com

Mike Kaliski wrote:

As others have mentioned, several articles appeared in various magazines
about the design of fractal antennas. The basic idea is to fold a
standard length of wire using a fractal pattern so that it fits into a
smaller space. One solution I saw was to wind a wire back and forth
across and along a plank of wood using pins or slots cut in the wood to
support the turns. Taking a four inch wide piece of wood around eight
feet long and winding equispaced turns you could easily fit 24 feet of
wire along the plank.
__ __ __
|__| |__| |__| | Using a pattern like this.

Other more complex or even three dimensional designs can fit more wire
into a given space. . .

This general category of antenna is often known as a "meander line", a
technique used for making electrically short antennas which has been
known and used for a very long time. "Fractal" antennas are a more
recent idea. They're a class of meander lines using particular
algorithms to do the meandering in a particular irregular way. Among the
interesting properties of some of these antennas is the presence of
non-harmonically related multiple resonances.

Many claims have been made for "fractal" antennas, among them being that
they provide the best efficiency for a given physical area. Steve Best,
VE9SRB, has credibly refuted this claim by creating some
randomly-meandered designs which are more efficient than claimed best
fractal designs. You'll find some of the history of this in the archives
of this newsgroup. The EZNEC models he developed are still at
http://eznec.com/misc/MI2/ for anyone interested to download and review.
Those models were also used for papers he wrote on the topic in IEEE
publications and, I believe, QEX. It's not clear what advantages, if
any, "fractal" designs would have over random or other meander
topologies for amateur use. The allure of "fractal" antennas seems more
to be in the interesting mathematics and the cachet of being modern and
revolutionary than in any demonstrable performance advantage.

Meander line antennas, including "fractals", share the same properties
as other electrically short antennas: narrow bandwidth and high
conductor current. The latter can result in poor efficiency due to I^2 *
R loss. Meander lines are better than some other methods of loading and
worse than others, depending on how the meander and other methods are
implemented. It's just one of the techniques which antenna designers
have in their bag of techniques to use.

Roy Lewallen, W7EL

On 20 Oct, 14:41, Roy Lewallen wrote:
Mike Kaliski wrote:

As others have mentioned, several articles appeared in various magazines
about the design of fractal antennas. The basic idea is to fold a
standard length of wire using a fractal pattern so that it fits into a
smaller space. One solution I saw was to wind a wire back and forth
across and along a plank of wood using pins or slots cut in the wood to
support the turns. Taking a four inch wide piece of wood around eight
feet long and winding equispaced turns you could easily fit 24 feet of
wire along the plank.
__ __ __
|__| |__| |__| | Using a pattern like this.

Other more complex or even three dimensional designs can fit more wire
into a given space. . .

This general category of antenna is often known as a "meander line", a
technique used for making electrically short antennas which has been
known and used for a very long time. "Fractal" antennas are a more
recent idea. They're a class of meander lines using particular
algorithms to do the meandering in a particular irregular way. Among the
interesting properties of some of these antennas is the presence of
non-harmonically related multiple resonances.
Snip

The non- harmonically related multiple resonance is quite important
now that all ham freqencies are not harmonically related.
I have found that it is possible for a single Gaussian antenna to
be resonant on many frequencies that are not related purely by
balancing the LC ratio at a given radiator length of choice
without reliance on traps or harmonics. These are contained
in there own band pass circuit and which can be moved at will.
The importance being that there is less interference between
band users as well as ambidextry and a constant impedance.
The case for Fractals is somewhat different to ham use in that for an
encapsulated
high frequency SYSTEM it matters not if what some would call the feed
line radiated
since usually power is not a main consideration making it ideal for
stealth purposes
since the fractal meanderings can be made to conform to any shape
structure while
maintaining a desirable LC ratio which with the use of laminated
circuitry is
becoming more available.

Art KB9MZ



snip

Roy Lewallen, W7EL

On Oct 20, 4:57 pm, art wrote:
....
The case for Fractals is somewhat different to ham use in that for an
encapsulated
high frequency SYSTEM it matters not if what some would call the feed
line radiated
since usually power is not a main consideration making it ideal for
stealth purposes
since the fractal meanderings can be made to conform to any shape
structure while
maintaining a desirable LC ratio which with the use of laminated
circuitry is
becoming more available.

It appears that the above MAY actually be a sentence. However, with
74 words in it, I get completely lost before I get to the end of it.
Would you be so kind as to diagram it for us, Art, or at least divide
it up into something a little more manageable?

Thanks.

Cheers,
Tom

On 20 Oct, 17:41, K7ITM wrote:
On Oct 20, 4:57 pm, art wrote:
...

The case for Fractals is somewhat different to ham use in that for an
encapsulated
high frequency SYSTEM. It matters not if what some would call the feed
line radiated
since usually power is not a main consideration making it ideal for
stealth purposes.
Fractal meanderings can be made to conform to any shape
structure while
maintaining a desirable LC ratio which with the use of laminated
circuitry is
becoming more available.

It appears that the above MAY actually be a sentence. However, with
74 words in it, I get completely lost before I get to the end of it.
Would you be so kind as to diagram it for us, Art, or at least divide
it up into something a little more manageable?

Thanks.

Cheers,
Tom

art wrote:
imaginations. Sorry. 73

Sorry.
There is a patent issued and many, many, more in the pipeline.

Having tons of patents means very little IMHO. It often just a PR
exercise, to make it appear the company has worthwhile intellectual
property.

I've seem some really useless patents.


Look up Fractus antennas or subscribe to the quarterly industrial
magazine
called Antennas.

Probably more worthwhile is something like the IEEE's antennas and
propogation, to which I do described.

The Fractus company was featured at the Antenna
exhibition in
Denver last month. Entrance fee was about $1000

And how many companies/individuals actually paid the $1000? I suspect
most got in with special offers, or fees were waived completely. This is
quite common - the published entry price of conferences is no measure of
quality.

On 21 Oct, 09:03, Dave wrote:
art wrote:
imaginations. Sorry. 73

Sorry.
There is a patent issued and many, many, more in the pipeline.

Having tons of patents means very little IMHO. It often just a PR
exercise, to make it appear the company has worthwhile intellectual
property.

I've seem some really useless patents.

Look up Fractus antennas or subscribe to the quarterly industrial
magazine
called Antennas.

Probably more worthwhile is something like the IEEE's antennas and
propogation, to which I do described.

The Fractus company was featured at the Antenna
exhibition in
Denver last month. Entrance fee was about $1000

And how many companies/individuals actually paid the $1000? I suspect
most got in with special offers, or fees were waived completely. This is
quite common - the published entry price of conferences is no measure of
quality.

I went to the same place a couple of years ago when they had the
International
industrial computor show.Universities got a 15% discount that I
believe was
also available to overseas attendants other wise you had to pay the
full wack.
Relatives were allowed in free for the last 2 hours on the last day.
Exhibitioners paid the full wack for space but were allowed a few free
tickets
for commentators.
Don't you ever have anything positive to say?
Art

John Doe wrote:
"I have a lot of time on my hands - "

Kraus calls fractal antennas "artistic antennas". Kraus says: "Fractals
are structures that preserve their shape at different scales."

In Figure 21-50 of page 774 of the 3rd edition of "antennas" (If you
don`t have it, you need it), Kraus writes:
"Note the impedance fluctuations of the fractal antennas compared with
the plate and square loop."

Not a ringing endorsement but there may have been progress since the
book was published in 2003.

Best regards, Richard Harrison, KB5WZI

On 20 Oct, 11:42, wrote:
On Oct 20, 11:34 am, "Mike Kaliski" wrote:



I agree. Incidently the origin of the idea for fractal antennae apparently
arose from the observation that hanging down the ends of a dipole, or
bending it to fit a limited site didn't affect the efficiency too much. A
university student decided to see just how much bending and could take place
before the antenna became unusable and hey presto, the fractal antenna was
invented and he had a thesis for his degree.

Mike G0ULI

Just linear loading with a fancy name..
Or the way I see it anyway..
The thing is... Most consider linear loading as
inferior to high Q coil loading,

A coil is linear loading as well
so a coil is just a fancy name?

"Most consider" agaim it looks like science is judged like the polls!



as long as the
coils are placed at the proper locations to
maximize current distribution.
But I can see their use in small items like
cell phones, etc..
I doubt if I would use one as a ham radio antenna
though.
Heck, my 160m "Z" dipole could be considered a
fractal. Even a dipole qualifies. All symmetrical
antennas can be called "fractals" if you wanted to
be strict about it.
MK