fractal antenna design software
Is here anybody who is interested in this exciting topic(means fractal antennas, fractal resonators, fractals in electromagnetics and other applications)? I'd like to share my experiences with other antenna researchers.
Eirp
I suspect this is just a topic for some authors whose sole interest is publishing. Please direct me to a meaningful application.
How about the bluetooth antenna ?
Hello friends!
I don't know how much you feel free with fractals and fractal antennas(FA), so a few words about.
Fractals in electromagnetics is a new exciting topic, it was found that FA offers some improvements to classic antennas. Note that fractal is a strongly irregular structure, very complex and self-similar. There is a big difference opposite of "clasic" ideally smooth, Euclidean geometry - fractals have a non-integer so-called fractal dimension. They are a "natural" product of Nature, i.e. trees, clouds, seacosts are of course fractals. I can write many things about it...
Thanks to it fractal antennas then have next useful properties:
-They are multiband (one small antenna can support GSM900,GSM1800,UMTS,PCS1900 and BLUETOOTH!)
-Their size can be much smaller than classical antennas (i.e fractal patches) ant they are still effective radiators
-Possibility to control gain
-...and others.
So it's my interest to study its behaviour, there is many non-answered questions at this field.
As a little example I attach two files:
1) Current distribution at Koch snowflake patch antenna (iteration level 3) at higher operating mode. Interesting fact is that the electric current is mainly localized at the fractal boundary. Current there has big density and the behaviour is like antenna array which results in higher gain. Of course, this antenna is also multiband. Computations were taken with IE3D, geometry created by self-made generator in MATLAB.
2) Analysis of Koch snowflake patch antenna (iteration level 5) based on cavity model. MATLAB+FEMLAB is used to calculate eigenvalues and eigenfuctions of this geometry. Presented picture electric field at 45th eigenmode. The behaviour is strictly different of, for example, rectangle, circle and so on.
I have many papers about this topic (and there exists many www pages too) and I hope that there is some antenna researcher which experiencies in with.
Nice weekend,
Eirp
[img]./uploads/SnowflakeIE3D.jpg[/img]
<font size=-1>[ This Message was edited by: eirp on 2002-02-16 12:32 ]</font>
2nd file here (see previous post)
Uploaded file: KochEz.zip
There's quite a good article in VHF Communications 4/2001 by Angel Vilaseca titled 'The Fractal Antenna'
At the end are a couple of links:-
h**p://fractenna.com/
h**p://www.crhc.uiuc.edu/~kutter/the-sis/
h**p://www.antlab.ee.ucla.edu/~johng/fractal.html
h**p://www-tsc.upc.es/eef/research_lines/antennas/fractals/fractal_antennas.html
If you really want I could scan the article?
Dear Odyseus,
Thank you for support; I know the links you've wrote (do you know www.fractus.com ?). I'm very intersted in the paper you offers me-can you scan it for me(and upload i.e. to FM1 or use my e-mail)? I will be very glad.
If you want some paper from Antennas&propagation, I have 24xCD (directly from IEEE with full search)with the papers in PDF(APmag(1953-2000), conference proceedings...). I can send you some paper. Of course this 15.6 Gigs archive cannot be uploaded:)
Thanks,
Eirp
Thanks for the interesting links.
I wonder whether it is neccessary to have one antenna working on 3-5 bands, as advertised in fractus website. Is it a matter of convenience for the manufacturer or something else?
If a fractal shape is printed on PCB with ground plane, then the self similarity is lost because the substrate is not scaled up or down. It seems like the word "fractal" is a bit misleading. If you put several arbitrary shapes together and feed them properly, you can get multiple resonances. Then where is the true value of fractal?
Uploaded the Fractal Antenna article to Filemanger1 Under folder
Odyseus/FractalAntenna as a WinRAR archive.
The pdf is some 8M big (because I wanted to keep the resolution of some of the graphs and diagrams plus I'm not too experienced in scanning and converting to pdf!)
First thank to Odyseus for the article, I'll download it this evening.
A few words to loucy:
I think that small antenna which can operate in many bands is very useful for modern telecommunications, don't you?
...
Fractal geometry have special properties and the selfsimilarity in not the only one. In fact, it was discovered that the selfsimilarity in fractal's geometry results to selfsimilarity in electromagnetic behaviour(for examples currents at Sierpinski monopole are selfsimilar on all bands. It results in selfsimilar radiation pattern at this bands). This also can be applied to antenna arrays with fractal distribution of radiators.
If the antenna is printed on PCB, the main role is played by fractal boundary which causes creation of a fractinos-localized vibration modes.
In the analyse of fractal antenna there are big problems. You can't do ideal fractal shape and the numerical computations are very hard. (I use Athlon 1.4GHz+1024MB RAM and still not as I want)
Eirp
PS: Two FA-links
http://members.fortunecity.com/scien...iencelinks.htm
http://www.bde.enseeiht.fr/clubs/iee...nts/roffe.html
I remember hearing about those Fractal Antennas years ago. April 1999 of MOnitoring Times had an article. They sound about as close to magic without breaking any physics laws... But I've never seen a commercial app. And how exactly do you design these things? One website had plans for a ham band antenna. Anyone know if there's software to make fractal antenna design easier?
hehe.... some have used genetic algorithms to create antennas... and if I remember right a company called linden innovation sold them, but i cannot find the link anymore. maybe they got bankrupt
Is it possible to use fractals at low frequencies.
How does the size compare to a helical- say at VHF?
Is a fractal a good receive aerial?
and like clouds
sea the world in general
pretty unpredictable
in there response to other elements
{ie the nail at the end of your roof re resonating or etc reresonating }
it has all been done before
and personaly is no more interesting
than the bucket of rain from any shape size or dimentions of cloud
the best day being bright and sunny and not a cloud in the sky ........
ie vertical 1/2 wave dipole will always work {and is many banded if you simply use a stacked array}
i can see some advatage in size for mobilephones
but for anything trhat isnt a toy
"hf vhf uhf"
pretty useless
if they were realy that much better "worth waisting time over" nasa would employ them in real aplications of shf like space bound repeaters and transponders
which oppeate around 1 - 10 ghz
and i never seen one used here
despite fractile tech being around now for as long as all of us here and some
dont you get it
a DIPOLE IS THE PERFECT FRACTILE
I think that fractal antennas will be used mainly in very high frequencies (~GHz). In this frequencies there are some advandages for using fractal geometry. You know, this is research phase.
Fractal geometry is something basic in Nature, so it must have special properties, or no? For example fractal seacoast causes strong damping of water waves (see Sapoval's fractal drums http://classes.yale.edu/math190a/Fra...ctalDrums.html).
Of course there are many topics in science where was fractal geometry successfully used...
But for short waves i prefer to use lambda/2 dipole too
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Eirp
Hi All,
eirp mentioned:
-They are multiband (one small antenna can support GSM900,GSM1800,UMTS,PCS1900 and BLUETOOTH!)
I'd like to know if you have designed a real multiband antenna what really works. If possible, post the model please.
I have made a Sierpinski antenna which can work at dual band, but it's diffuclt to control the ratio of frequencies. Matching is a little bit time consuming. When I got PCS band, cellular band gone.
Anybody has good idea for dual band antenna (cell & PCS band)? Most important - similar patterns for both bands.
Any valuable reply is appreciated.
rgz
jjantenna
Hi everyone,
I'ld like to know what European or American society produces fractal antennas.. Does anyone know it?
Thanks in advance
Lupin
Hi!
I know only FRACTUS from Spain: www.fractus.com
and
FRACTENNA from USA: www.fractenna.com
I have information that patents really belongs to FRACTUS.
Regards,
Eirp
Thanks for your informations.
Do you know what are main fractal antennas applications except to mobile phone use?
Thanks
Lupin
PS: if you have questions about microstrip antennas, components, e.m. softwares, phased array, please ask!
Hi!
I think it's still mainly research interest. And the companies keeps their current work in secret.
Applications are clear from the main properties.
I have about 100 papers on this topic, I can upload next week some.
Regards,
Eirp