I am looking for the construction article "FRACTAL Antenna for 10m" that
appeared sometime ago in I think either QST, Ham Radio, or 73 magazines.

I have a lot of spare time on my hands - so I thought I would like to
construct one and use it portable as I live in a Antenna Restricted
Community.

73's

"John Doe" wrote in message
...
I am looking for the construction article "FRACTAL Antenna for 10m" that
appeared sometime ago in I think either QST, Ham Radio, or 73 magazines.

I have a lot of spare time on my hands - so I thought I would like to
construct one and use it portable as I live in a Antenna Restricted
Community.

73's

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.

Older interpretations of antenna theory predicted that the interaction
between the closely spaced wires would effectively short out the turns and
you would end up with the equivalent of an 8 foot length radiating element
rather than the 24 feet of wire wound along the plank of wood. While there
is interaction, the apparent reduction in radiator element length is not as
bad as was predicted. So fractally wound elements can be worth the effort
where space is at a premium.

It is significant that the majority of development work into these antennas
has taken place for frequencies above 1Ghz. Main applications include mobile
phones, RF ID tags, security and remote sensing tags. At Ghz frequencies,
exotic patterns can be easily etched onto circuit boards at minimal cost.
Koch snowflake like fractal patterns combined with circular whorls seem very
popular with commercial manufacturers. A google search will reveal quite a
few pictures of what is being produced.

It is not necessary to try and duplicate the complexity of professional
designs. The main criteria seems to be to keep the wires as evenly spaced as
possible, hence the width of the winding should be approximately equal to
the linear step along the plank of wood or whatever support frame you are
using, i.e. 4 inches up, 4 inches along, 4 inches down, four inches along, 4
inches up, etc. etc.

As you will doubtless appreciate, this is similar to a three dimensional
coil being wound on a former. Because the fractal winding is flat, there are
fewer inductance effects.

Obviously fractal antennae are designed for a specific frequency or band,
but the type of winding pattern and spacing have an effect on the bandwidth.
Obviously you will need two mirror image windings to create a dipole
antenna, ideally as closely matched in dimensions as possible. Efficiencies
can approach 50% of a full sized radiating element.

Hope this helps

Mike G0ULI

On 20 Oct, 04:59, "Mike Kaliski" wrote:
"John Doe" wrote in message

...I am looking for the construction article "FRACTAL Antenna for 10m" that
appeared sometime ago in I think either QST, Ham Radio, or 73 magazines.

I have a lot of spare time on my hands - so I thought I would like to
construct one and use it portable as I live in a Antenna Restricted
Community.

73's

As others have mentioned, several articles appeared in various magazines
snip.
Obviously you will need two mirror image windings to create a dipole
antenna,

Mike,
the definition I arrived at is that as long as the wire represents one
wave length,
is resonant and in equilibrium while at the same time holding to the L/
C ratio of the material in question.
This can be produced with just two degrees of freedom by folding
the wire at the half wave point
and then wind the two wires in pancake shape/form.
You can also wind two in series where capacitive actions
between them can create a variety of results.
The important point is that one must hold to the
conditions set in the definition
(no exceptions)

Art





ideally as closely matched in dimensions as possible. Efficiencies
can approach 50% of a full sized radiating element.

Hope this helps

Mike G0ULI

"art" wrote in message
oups.com...
On 20 Oct, 04:59, "Mike Kaliski" wrote:
"John Doe" wrote in message

...I am looking for
the construction article "FRACTAL Antenna for 10m" that
appeared sometime ago in I think either QST, Ham Radio, or 73 magazines.

I have a lot of spare time on my hands - so I thought I would like to
construct one and use it portable as I live in a Antenna Restricted
Community.

73's

As others have mentioned, several articles appeared in various magazines
snip.
Obviously you will need two mirror image windings to create a dipole
antenna,

Mike,
the definition I arrived at is that as long as the wire represents one
wave length, is resonant and in equilibrium while at the same time holding
to the L/C ratio of the material in question. This can be produced with
just two degrees of freedom by folding the wire at the half wave point and
then wind the two wires in pancake shape/form.
You can also wind two in series where capacitive actions between them can
create a variety of results.
The important point is that one must hold to the conditions set in the
definition (no exceptions)

Art

ideally as closely matched in dimensions as possible. Efficiencies
can approach 50% of a full sized radiating element.

Hope this helps

Mike G0ULI


Art

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

On 20 Oct, 09:34, "Mike Kaliski" wrote:
"art" wrote in message

oups.com...



On 20 Oct, 04:59, "Mike Kaliski" wrote:
"John Doe" wrote in message

om...Iam looking for
the construction article "FRACTAL Antenna for 10m" that
appeared sometime ago in I think either QST, Ham Radio, or 73 magazines.

I have a lot of spare time on my hands - so I thought I would like to
construct one and use it portable as I live in a Antenna Restricted
Community.

73's

As others have mentioned, several articles appeared in various magazines
snip.
Obviously you will need two mirror image windings to create a dipole
antenna,

Mike,
the definition I arrived at is that as long as the wire represents one
wave length, is resonant and in equilibrium while at the same time holding
to the L/C ratio of the material in question. This can be produced with
just two degrees of freedom by folding the wire at the half wave point and
then wind the two wires in pancake shape/form.
You can also wind two in series where capacitive actions between them can
create a variety of results.
The important point is that one must hold to the conditions set in the
definition (no exceptions)

Art

ideally as closely matched in dimensions as possible. Efficiencies
can approach 50% of a full sized radiating element.

Hope this helps

Mike G0ULI

Art

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- Hide quoted text -

- Show quoted text -

Yup He is way ahead of the average ham but he did have an engineering
background
now he is making a lot of money with a product that the average hame
decries.
I was looking at Tom's page W8ti and I was very suprised to see that
he states
an antenna must be straight no less plus a lot more in accurate
statements.
He has written articles as have many on this newsgroup but as I have
stated before
believe what you want but often it is not correct.
On this newsgroup I am often reminded of the scene around madame
guillotine with
the . hoards of baying crowds of the ignorant looking for blood.
Have to make a correction on past statements tho, instead of one
wavelength radiator it should read
" one wavelength or longer" because of the genorous number of
harmonics.
Cheers
Art KB9MZ....XG (uk)

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

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

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