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Fractal 10m Antenna
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 |
Fractal 10m Antenna
On 19 Oct, 18:31, "Stefan Wolfe" 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 John, there is no such thing as a fractal antenna. Antennas can only function in real space-time. It is a only figment of certain matematicians' imaginations. Sorry. 73 Sorry. There is a patent issued and many, many, more in the pipeline. Look up Fractus antennas or subscribe to the quarterly industrial magazine called Antennas.The Fractus company was featured at the Antenna exhibition in Denver last month. Entrance fee was about $1000 At the companies inception it won seed money from the military to continue their work so the antenna is viable. |
Fractal 10m Antenna
Oh no Here we go again.
10 years ago this was a major topic and ridicule |
Fractal 10m Antenna
On Oct 19, 11:11 pm, "R. Scott"
wrote: Oh no Here we go again. 10 years ago this was a major topic and ridicule Yea, if there is a new company called "Fractus", I bet a character called Chippus is about to have kittens. Maybe six or seven of them. With little curly tails... Fractus... Kinda reminds me of Festus... Maaaathheeeewwww! What thar heck is that curly waaar you got stuck on that there horses head? Doc, have you ever done seen such a thang? Miss Kitty! Maaaatheewws horse has a bed sprang on his head! I done declare! |
Fractal 10m Antenna
"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 |
Fractal 10m Antenna
On Oct 20, 12:19 pm, wrote:
Oh no Here we go again. 10 years ago this was a major topic and ridicule From the many Luddites on this group. Derek. |
Fractal 10m Antenna
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Fractal 10m Antenna
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 |
Fractal 10m Antenna
"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 |
Fractal 10m Antenna
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) |
Fractal 10m Antenna
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 |
Fractal 10m Antenna
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 |
Fractal 10m Antenna
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 |
Fractal 10m Antenna
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 |
Fractal 10m Antenna
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 |
Fractal 10m Antenna
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. |
Fractal 10m Antenna
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 |
Fractal 10m Antenna
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 |
Fractal 10m Antenna
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 |
Fractal 10m Antenna
In article , Roy Lewallen
wrote: 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 Hello, and you make some good points, Roy. (I always pay close attention to many of Steve Best's IEEE papers on antennas). While I've not analyzed or experimented with antennas based upon fractal patterns I have always wondered whether broadband performance could be achieved since fractal patterns would repeat with electrical (frequency) scaling. Granted, these patterns unlike, say a logarithmic spiral, would only repeat at discrete values. Your comment above indicates this is not the case, however. Sincerely, and 73s from N4GGO, John Wood (Code 5550) e-mail: Naval Research Laboratory 4555 Overlook Avenue, SW Washington, DC 20375-5337 |
Fractal 10m Antenna
John Doe wrote:
"I have a lot of time on my hands." I recall the Fractenna man, Dr. Chip Cohen, used to define fractals as self similar elements assembled to cover a wide range of frequencies. That roughly conforms to Kraus, "structures that preserve their shapes at different scales." Kraus` conical spiral and log periodic antennas in Figure 310 on page 68 of the 3rd edition of "Antennas" also seem to fit the repeating structures of different scales designed to produce very broad bandwidth with moderate gain and might be called fractals. Best regards, Richard Harrison, KB5WZI |
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