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Fractal Antennas more efficient?
Mike Hicks writes "Scientific American has a short article talking about fractal antennas. They can be 25% more efficient when used in place of the stubby antennas on cellular phones. An antenna that's fun to look at -- who'd a thunk it? "
They already can monitor any cell phone conversation and triangulate position in less than five minutes anyway.
You mean it is possible to do this, but of course it is not legal to do this. That doesn't mean it doesn't happen and it doesn't mean you should blindly accept it!
most people are unbelievably boring.
How do you know? Have you been listening? I think maybe you have.
It is simply not practical... for the government to monitor over 270,000 people.
Really? Sounds simple to me. Do you know this is not possible? Most of the system is almost there now. If it was all automated then why not. How do you think all those people get their bill and should we accept it?
Don't give them a reason to watch you, and they won't.
That is really funny! I guess your one of those people who think that if you are truly innocent you wont be convicted. Have fun with your rude awakening.
Why don't you go to the EFFs web page a look around at what has been happening for the last few decades.
www.eff.org
Linux is only free if your time has no value. Windows is only free if you threaten to use Linux.
Europe and Asia only, eh? That would explain the (for Americans) incorrect spelling of "Authorized" as "Authorised" on one of the doors later in the movie.
BTW: Did anyone else notice what looked like a Hewlett Packard ad behind the Subway train just before it crushed a Smith? Interesting bit 'o subliminal adevrtising!
>>That sounds like a fun idea. I hope the fact that it's now archived on Slashdot, a public forum, as a date-stamped posting will ensure that we can all make our pyramidal antennas without worrying about someone coming along and patenting the idea. 1 year, you can't file the patent.
*sigh*
Phil Reed sez:
There's been a fair amount of discussion on the fractal antenna on various ham radio mailinglists, and whilst the antenna IS patented the person who owns the patent has explicitly given permission for the antenna to be used in non-commercial applications below cellular band.
On the Fractenna Homepage there are also explicit instructions on how to build a fractal antenna for various ham radio bands.
Warning: Subjects of a technical nature relating to both fractals and radio bandwidths follow. It shall be assumed that you have at least some grounders in both fractals and in antenna design if you are reading past this point. If you don't know what the hell a Koch curve, common ham radio terms, wavelength, or Yagi antennas are then the following will probably be of no use whatsoever. :)
As far as I can tell, apparently the fellow has made the antenna in the rough outline of a fractal resembling a Koch curve with squares and pointing inward instead of outward and with triangles (as in normal Koch curves). I don't know of too many hams using them just yet, but once programs are written where one can custom-design such an antenna by both wavelength and iterations then I'd expect more folks to be using them. There's been a fair amount of excitement in the QRP community at least, because one can pack a lot of antenna in one space and antennas for 20 meters and below that don't require longwire hookups, Slinkys, or towers become practical.
The designs for use in ham radio seem to be variations of Yagi square antennas (fairly common for homebrew use) where instead of a square one uses the "modified inverse Koch square" (for want of a better term for the fractal used) for the upper and lower ends of the band. These are better suited for directional antennas, of course (as are all Yagis); if one didn't want to use it as a Yagi and wanted a non-directional antenna I see no real reason you couldn't use a fractal antenna as a sort of modified loop antenna. (Folks doing AM DX listening in cramped quarters where installation of a longwire antenna is impossible ought to like that. ;)
If memory serves, calculating wavelengths for the "Yagi fractenna" is a bit more of a bear than configuring wavelengths for the normal type of Yagi. Again, though, it should be possible to figure out a way to rig up a quickie program to determine wavelength.
Just like the man said, the Fractenna is not going to give you ANY more gain than a Yagi antenna of comparable wavelength. What it does do is allow one to install a rather large (in wavelength and in wire length) antenna in a much smaller space than one would normally do so.
(end technical discussion)
Now, as for other interesting uses of fractals...I have heard of a number of kite enthusiasts who have built working kites based off of Sierpinski sponges. (Sierpinski sponges are just like Sierpinski gaskets or triangles, but in three dimensions. ;) Apparently the things get amazing lift--one has to be careful not to let the kite drag you because you're dealing really with upwards of four or more box kites! :)
A quickie search of Alta Vista for "fractal kite" or +kite +Sierpinski should lead you to some articles on how to make them and fly them. ;)
I seem to remember hearing somewhere that the mandelbrot set is not, technically, a fractal.
Can anyone back me up/refute this?
Why is this at -1? Sure, the spelling is not exceedingly accurate, but it's certainly not redundant, as whoever moderated it claimed. It asks when we can see these antennas in common electrical gadgets, and whether they will cause prices to go up. These seem like legitimate queries to me, and are not redundant since this is the first time they have been asked in this article's comments section.
10 PRINT CHR$(205.5+RND(1)); : GOTO 10
I think it's time to break out the SpiroGraph set and see what other designs we can come up with... heh heh
I don't think that the Mandelbrot would work in this situation because it is not symmetric around a point and self-similar. Especially at a level in which you could burn in silicon.
--mere mortal--
I seem to recall that the guy who discovered the fractal antennae phenomena was stuck in an apartment where he couldn't have an antenna out his window, so he just bent a hanger into a rough fractal shape and his shortwave reception was acceptable.
--mere mortal--
Look, just because the government has the abillity to listen into your cell calls doesn't mean that they do.
I am not saying that they never have, but they rarely do. It is impractical and almost useless to monitor everyone.
Why does any time an artical on information exchange is posted on slahsdot does everyone start screeming that the FBI, CIA and NSA are monitoring everyone.
The scariest part of these posts is that so many people are so paranoid.
Unless the government has a good reason to watch you, they most likely are not.
You say that anyone who doesn't believe in the government monitoring is just a sheep, but if you bothered to look at the issue from a neutral point, the eveidence of monitoring is much less, both in amount and quality than that against it.
I'll have to snag a copy today and review the article. I'm not up to speed on fractal antenna design, so it'll be interesting. Remember that, however, for GPS antennas, reception of multiple-reflectionsignals degrades your result rather than improving it. You want to maintain a Right Hand Circular polarization to diminish multipath-delayed signals (13-20dB improvement in signal selection; less confused receiver) for your best GPS performance.
And, yes, I realize that it'd be nice toget better performance under trees and in urban canyons but that's more a function of the GPS satellties transmitting a paltry amount of power relative to free-space loss and range. But a lot of power when one considers power generation on a satellite!
Never ascribe to malice that which can adequately be explained by tenure.
True, as far as it goes. But the really dangerous thing is when cells start to divide before the DNA damage hasn't been fixed up. That's why it's very important to not get any cuts or damages if you have radiation damages (never do surgery until the patient has recovered). It can mean the difference between "you die" and "you're doing pretty good".
TA
Police state eh?
hum speeking of the Young Communist League, we do not live in a police state, the democratic, free market of the United States, and the mostly demcratic, mostly free market of Canada, austrialia, and the UK are just about the farthest you can get from a police states. Need I tell you the closest to police state.
Personally I like freedom of speach, religion, and economics.
Hum i wonder if you would have just gotten pulled over in a communist block country if your gf was a member of a democratic party.
Do not take for granted the freedom that you have, complaining that you were stoped by a bored cop is nothing compared to what might happen in a real police state.
Try using you rational, it might help you see the situation without having to resort to paranoia, which gains nothing.
That's what you get for calling 900 and 976 numbers.
Actually, the one they're using is the Sierpinski square, but yah. :-)
This is from rec.radio.amateur.antenna:
On 8 Apr 1999 11:49:09 GMT, fractenna@aol.com (Fractenna) wrote:
>>Certainly. In the published examples of Minkowski loops (Cohen and Hohlfeld,
>>CommQuart, Winter 1996), and Koch monopoles
>>(Puente et al. IEE Electronics Letters, Jan 1998)the perimeter constitutes an
>>electrically long structure which introduces loading and phasing: the current
>>is far from uniform even though the structure may have largest physical
>>dimension of 1/10 of a wave or less. The fractal structure cancels in one
>>polarization and adds in the other, producing a power pattern virtually
>>identical to that expected from a 'straight line', loaded short antenna. The
>>field strength exceeds that of other loading methods in most practical uses.
This is what I understand that to say, please correct me if I am wrong.
1.) In larger sized antennas, the "fractal" loading has current taper like in a linear loaded or any of the nattennas that are not
considered end loading.
If that is true, then the fractal has LOWER radiation resistance than a uniform current near-uniform phase antenna of the same dimensions.
2.) The fractal antenna has more loss than other loading methods when small.
3.) The pattern is the same as other straight line loaded antennas.
If all that is true, what is the advantage?
>>As said many times here and elsewhere, when very electrically small this
>>advantage is no longer realized.
OK, so it doesn't work on small antennas (like you initially claimed a few years ago).
>>When slightly larger, the fractal structure introduces phased
>>echelon/collinear
>>effects which give additional gain (this property is shared by Landstorfer
>>antennas, which are larger I might add).
OK. Collinear or echelon antennas have gain, even if the feedline is incorporated into the element. Still no advantage I can see, other than elimination of a feedline by, in effect, using a single wire feedline / phasing line. Like the Bobtail curtain or Bruce array has done.
>n the case of frequency independent antennae, this advantage is well-known.
>>And it is impossible to make truly frequency independent antenna without a
>>self similar--fractal-- structure.
Is a terminated Rhombic a fractal? A terminated V? A terminated longwire?
Is a discone a fractal? Is a biconical monopole a fractal?
Is a bow-tie a fractal? What about horn antenna? What about a
transmission line gradually flaring out to a large opening with the same Zo throughout?
All of these antennas are "frequency independent", some have considerable gain. Some are omni-directional in one plane.
You wrote:
>And it is impossible to make truly frequency independent antenna without a
>>self similar--fractal-- structure.
I think that statement is absolutely wrong. There are DOZENS of
examples that disagree with your claim.
Since the fractal, when larger, behaves like a linear loaded
antenna...when smaller is less efficient....and obviously isn't the ONLY frequency independent form.... what is the advantage?
73 Tom
}
I think I agree with Tom's (W8JI) last comment.
It's a little more complicated than this. The antenna efficiency is really the amount of
energy that doesn't get lost in heating up the
antenna through resistive losses.
effciency = ( Impedence - resistance)/impendence *100
where the impedence is the load presented to the radio and the resistance is the part of the load that gets absorbed in the antenna.
(derive this equation yourself - remember
P = I^2 R)
So if you lower the resistance you get a more efficient antenna.
Rubber ducks are notorious for having a high
resistance because of all the coiled wire needed to match the impedence of the radio. So a 25% improvement is not bad.
To see this, measurements i made on a 10Meter mobile antenna will be useful. The impedence was 50ohms and the measured resistance was 20ohms (the swr was 1 or close enough). therefore the efficiency was 60%. If i used a better antenna with 10 ohms resistance then i'd get 80% efficiency which is quite an improvement. (neither are as good as a dencent dipole where you can get into the 99% range).
Fractal antennas are actually a folded up
"log periodic" antenna. Sort of like the old
TV antennas, but packed into a small package.
Since i'm not quite cowardly my email is
robert.harrison@acm.org
and my call is
n3ikc
daveo does not type in caps any more but feels he must geet his points acoross to the moderators. he is sorry that his style of wrting iritates you but hey what can he do if suddenly someone asked you tyo write differently would it be so easy? no so daveo is sorry
-DAVEO
After all, real men use vi, the superior and ubiquitous editor. So, take your silly emacs, you silly emacs user, roll it up real thin, put it in your pipe and smoke it. Oh wait, I forgot. Emacs is so freakin' big there's no way it could fit in any normal pipe.
And need I say, Go boilers!!
(that operate at 900mhz & 1800mhz), & for those dual analog/digital AMPS/D-AMPS cellphones, that will be used in outback Australia from next year.
Sounds like it would also be the purfect antenna for that Ericsson world cellphone that will handle GSM (digital), AMPS (analog) & D-AMPS (digital/analog) across five frequencies.
i'd just like to point out that the energy of an electromagnetic emmission does not vary with the type or frequency of emission. a 10 watt FM broadcast radio wave (~100 MHz) carries just as much energy as a 10 watt PCS signal (~1.8 GHz), or a 10 watt light bulb (~700 nm to ~350 nm, or ~400 GHz to ~1000 GHz). as the frequency changes, the signal's ability to interact with your body changes -- your body is resonant at about 100 MHz, and your head is resonant at about 1 GHz.
the fact that cell phones use microwaves to communicate doesn't prevent them from potentially harming you, even at 100 mW. not that they do, but they might. no one knows for sure.
your cell phone would only have to generate about 1 watt to cause gradual damage to your eyes, usually leading to glaucoma and cataracts over a span of years. this could also cause cancer, or have other unpredictable side effects, in your brain. one report even suggested that using a cell phone makes your brain work and respond faster.
gamma and X-rays don't cause mutuations, usually. they cause cancer. (although, if you wanted to argue that cancer was a mutation, i guess i couldn't present a good counter argument.) nuclear radiation only causes superpowers in comic books.
a good link to check if you're interested in the spectrum: NASA's page on the spectrum.
Yeah, In fact, the first picture on the site showed a phone with an antenna just like that.
Although, I would reccomend you use photo etching rather than press-and-peel... I'm sure some of the fractal properties would be lost with inaccuracies associated with press-and-peel type methods.
Daveo, my man, Why'd you give up the caps?
Sometimes, saying nothing says more than anything at all... ;-)
Sorry to mention it, but that answer was unbeleivably boring (as are most one liners, including this one).
I contest that "unbelievably boring" statement. In Canada, the land of free scanning, I've spent some time listening to others phone conversations, and it's way better than TV...
ok, lets makes this blisteringly clear
DAVEO is a person. Most likely, a person who posts in hopes of pissing people off. Since we can't do anything about (you can't shut him up because he *attempts* to make a point) all you can do is suck it up, deal, and hope whoever is on that end of the connection grows up *soon.*
--------------------------
thats a nice trie but daveo said how many times not how long try rephraseing your anser
-DAVEO
For example, envision that in some undisclosed future I was walking by a crime scene 10 minutes before it happened; the police could, in theory, scan the entire area for passersby within the hour, and I could be picked up for questioning, even though I didn't do anything.
Farfetched? You'd might be amazed. Even worse, since most people won't be directly affected, the issue would not be discussed, rather swept under the rug, and those affected would be going through hell. Remember -- a democracy rules through the vote of the masses -- but we need to protect the rights of the individual too, even those who are not "mainstream". And that's where governmental oversight worries me.
I know they probably know everything about us already, but I'd rather not hand them the information on a silver platter, all the same :-)
--bdj
well dendrite someoen *nicley* pointed out to daveo that the caps were iritating and daveo considers people's feelings; he wan'ts us all to have a unfiied /. in which we may all share our feelings on the tecnhical issues that we discus; he does *not* troll or flaimbait and does *not* want fights he wants piece and harmony!
-DAVEO
In the past few years, handheld cellular phones have been sold to the US public by the tens of millions. In the past few years, there has been no dramatic upsurge in the incidence of brain cancer. Draw your own conclusion.
I have seen discussions about the 'benefits' of fractal antennas many years ago. The consensus then was that the 'fractal antenna' concept was a troll.
Fractal antennas can't break any fundamental rules regarding antenna design. The fractal designs just looks more modern and gives a high tech impression to the layman.
Fractal antennas do in fact work but you can get the same performance or slightly better by other design methods. The 25% performance increase is just marketing hype.
Antenna physical area is setting the performance limits. With a small given area there is no way to build a high performance antenna, fractals or no fractals.
//Gunnar
--- Linux or FreeBSD, it's like blondes or brunettes. I like both. ---
Free scanning? Does that mean I can buy a scanner up their that dosen't exclude celluar?
HIllbert fractals might make a good antenna if you're looking for total length in a condensed area, but the lengths of the straight segments in them are almost all the same length, and the ones that are different are powers of two above the smallest ones. Another thought that came to my mind ist that Golomb Rulers, specifically Optimal Golomb Rulers, might be quite usefull here...
You don't say I'm not an expert and that I'm an idiot because I'm saying it right here.
"I'm not an expert, and I might even be an idiot."
In the past few years, handheld cellular phones have been sold to the US public by the tens of millions. In the past few years, there has been no dramatic upsurge in the incidence of brain cancer [yet].
cancer is patient. well that is, if cellphones really are carcinogens.
"Computers don't make mistakes, people do."
offtopic, but.. people created computers. what if what they created is mistaken? then indeed computers could make mistakes even if the software is proper. ie, pentium (math?) bug, etc
yes.
NASA does a lot of this. It's a little more complex than just printing it, though, and I haven't seen any fractals (my subscription to NASA Tech Briefs lapsed.)
You have to have more than one layer, and it works best with slot antennas. A slot antenna is one of the solutions to Maxwell's equations that can be done; the length of the slot is the width of the wire, and vice versa. They use the technique to make antennas that are flat, for e.g. sticking on the skin of an airplane or spacecraft.
Actually, it sounds like an ideal use for the fractals, and if the picture is an indication, that's pretty much what they're doing.
Regards,
Ric
creepy. do they also have a screen in their living room which can see them when theya re naer and hear them regardless of where they are in the house?
Really not surprising... the transmitters in cell phones put out a lot of heat!
Regardless of why you were asked for your ID for a cop, you apparently were not detained or arrested, simply asked for identification. I don't see what the big deal is if the cop did not harass you in any way.
;)
Most likely, there was a "suspiscious person on foot" recently reported in this suburban or urban area (am I right about the area?). This is rather common and in my time as a police aide I heard this type of call frequently. For instance, a resident might look out the window and see someone trying door handles on parked cars. Anyone on foot around that neighborhood would be ID'd if they came anywhere close to the description, regardless of whether or not they were acting suspiciously when spotted by the officer. Of course he can't do anything to you for possibly being a person who was alleged to have been seen acting in a suspiscious manner, but he can get your ID and contact you later if it turns out a more serious crime was going on.
It would be no surprise if the government was checking up on you, if you communicate with foreign nationals or antiestablishment groups or if you are involved with illegal drugs. HOWEVER, the problem is that a cop asking who you are doesn't look like very serious surveillance to me -- if you were really being watched by professional government observers, a cop who was involved in the least would have known who you were in the first place and not had to ask.
But if you're really paranoid, maybe he was playing double agent and trying to let you know *they* are on to you
Yeah, 270.000,000 not 270,000. Sorry about that... :)
49 20 68 61 76 65 20 74 6F 6F 20 6D 75 63 68 20 66 72 65 65 20 74 69 6D 65 2E
You mean it is possible to do this, but of course it is not legal to do this. That doesn't mean it doesn't happen and it doesn't mean you should blindly accept it!
It's possible. Therefore people do it. It doesn't matter whether you accept it or not. The only thing that can be affected is how much it is used, and how much those using it are prosecuted.
most people are unbelievably boring.
How do you know? Have you been listening? I think maybe you have.
Most people are unbelievably boring. Most people have done illegal & blackmailable things. (not all of the illegal things are boring, but most are). First step is to make victimless crimes legal. Second step is to either totally ban surveillance or else to make it totally open. The latter may be our only choice.
It is simply not practical... for the government to monitor over 270,000 people.
Really? Sounds simple to me. Do you know this is not possible? Most of the system is almost there now. If it was all automated then why not. How do you think all those people get their bill and should we accept it?
Don't give them a reason to watch you, and they won't.
That is really funny! I guess your one of those people who think that if you are truly innocent you wont be convicted. Have fun with your rude awakening.
They'll be watching you regardless of who has their way. Don't you think it'll be better if you can watch them as well? Universal surveillance will also make alibis a lot easier.
Why don't you go to the EFFs web page a look around at what has been happening for the last few decades. www.eff.org
The EFF works for two things: freedom and privacy. They are both very important. However, the privacy battles have to be in the right arena. Strong, routine encryption is important. Privacy in one's own home is important. Universal awareness of privacy holes like cell phones is important.
Eliminating very useful security features because of vague privacy concerns is harmful. If I press 911 on my phone, I want them to find me. If I don't want them to find me, I can turn off the phone (or remove the battery if I am really paranoid).
Bryan
The fractal kites page is very cool.e ll
There are some pictures of Alexander Graham Bell
flying one in his back yard in 1903!
http://www.sct.gu.edu.au/~anthony/kites/tetra/b
Starman97@Gmail.com (bring it on spammers)
I forgot the effects of reflected signals. With the kind of precise timing those things need, that would obviously be a problem.
Dammit, I wish there was some easy way to get good reception without making the unit huge. My friend has a 12 channel Garmin with a fairly large detachable antenna, and it constantly loses satelites.
My unattainable dream is to have only one unit i ever take anywhere. Something like a combo cellphone, pilot, gps. Ahhhhhhh.
Vidi, Vici, Veni
Of course, the feds do monitor this bulletin board. You scary bunch of hairy liberals, you.
Big Al
-----------------------------------------------
Vice is its own reward
--------------------------------Quentin Crisp---
" er...if you are worried about the radiation damaging you, bear in mind that the antenna is already right next to your head. "
The Point is that it isn't omnidirectional. It can only go in one direction, where *all* of the radiation goes. With todays antennas the radiation is spread out, which is at least *better* then when it goes only in one direction.
" the signal will have passed through buildings, cars, trees, and all sorts before getting to your phone. "
Yes, but that has already been accounted for, and that is what causes the bit delay problems. Still, that is not such a big 'energy stealer' as would it have to go through the hand, or for that matter the head.
The Point (here I go repeating myself) is that it wouldn't work in todays phones, neither in tomorrows phones. Perhaps in the day after tomorrow, but by then we will probably use some other kind of system for transferring the signals...
I will be brief here and this will be my only post on slashdot.
The ComCyl Dualband stubby you are referring to is indeed "25% more efficient". Indeed, the field strength of this antenna attached to a commercial dual band cell phone is, within measurement error (0.2 dB), equivalent to a 1/4 wave whip. In comparison, a standard (coil) stubby is -1.8 to -3 dBd, depending on manufacturer.
Mr. Chenoweth and I are submitting the anechoic chamber measurements for publications.
Those cranks who "claim" that I am breaking some laws of physics, or asserting bogus facts need YOUR objective scrutiny:
WHERE IS THEIR DATA!
Ask them about THEIR MEASUREMENTS and MODELS.
I think the nick 'Anonymous Coward' says it all for them..
Cordially,
Nathan Cohen, Ph.D.
Sucks to your meta-alt-control-shift command set! I'll stick to my good old reliable escape key, and set worlds afire with vi, the rough-and-ready text editor. Real men don't need all those user-friendly fluff menus and real men certainly don't need four modifier keys to type in a command.
Oh, and real men never, ever, ever program in LISP.
Go Boilers!
Hello OM;
That is most certainly not correct. Could you kindly pass along the page and issue? I will be happy to point out the inaccuracy, if indeed it says what you remember.
Cordially,
Nathan Cohen, Ph.D.
First time a story on fractal antennae is posted on slashdot is what you mean by "First"?
I wonder when these will become standard on cordless phones, cell phones, etc...
It would be neat to see if they could engineer a fractal antenna using the latest in micro-eletronics that would be a really really deep physical copy of the Mandelbrot set :)
--
Know where I would really like to see these? GPS receivers. Those could use all the reception technology they can get. Anyone know if there are any plans to include this in a handheld GPS receiver? If so, where do I sign? :-)
Vidi, Vici, Veni
This could finally explain why the radio reception on my 1976 Honda Civic improved when I jammed an old, twisted-up coat hanger in place of the broken off antenna...
I wonder which fractals make the best antennas, though? Hmmmm, I smell a research project.
"Tomorrow's forecast: a few sprinkles of genius with a chance of doom!" - Stewie Griffin
Does this mean that an antenna fashioned as a classic fractal such as the Sierpinski triangle be patented?
:)
Who said science is dying? The fun continues
-tired of cookies, btyler@ece.utexas.edu
its been going on a loong time. they guy who started it (and ive met him) is a short chubby bloke from the MET college here at BU. (search for him on www.bu.edu)
Re: First!: I just think he's proud of posting the first message for this particular news item.
Anyway...I recall hearing that it is safer to keep the antenna always extended (while talking) on current cell phones to minimize radiation exposure. With the entire antenna unit inside the phone.....ugh....I feel bad enough using any cell phone as is...I can feel my brain cell DNA being modified during usage.
is in MS Word format :P
Peter
They are available in Europe and Asia only, for now. The phone is made by Nokia, model 7110
"Even Prophets don't know everything"
Hey, I could pick up twice the stations with just a little bigger mitt. Can this be applied to the old "rabbit ears" antennas for old-fashioned TV ?
The guy probably wanted the very same phone, which will ring right after he gets it! Well, dude, just make a smart decision and choose the right pill!!!
daveo has read the articile but still has a few things unclear. can anywon tell daveo when he will see these new antennas in his telephones or other commonly used household appliances? what about prices, will the prices' costss be higher?
-DAVEO
Actually, yes, that was a hilarious piece of advertising. At least it was subtle, the Panasonic/FedEx/Nokia/Rayban ads were a LOT less subtle. I saw the HP the second time i saw the movie and every time after that (now up to 6, plus all the times I've watched it on my new VCD. Great copy, this VCD is actually of the home video print.. proper music, proper brightness, proper centering for the widescreen->tv aspect transition)
If a fractal antenna works more efficently.. wouldn't a Pyrimid who's 4 sides consisted of the fractal designed antenna work even more efficently in all directions? The way the atenna is now.. it would function like that in a directional finder.. where when the side of the atenna is pointing to the transmitter or receiver.. the signal would be weak.. and when the broadside is facing.. it would be strong. By making it more of either a 3 or 4 sided pyrimid.. you'd have more surface area receiving the signal at one time.. allowing for a better reception at all sides and therefor a longer distance of receiving a clear(er) signal.
Ron Rossman
rjr162@psu.edu
UGrad Student in the College of Engineering
Penn State University
Australia retains much of it's British heritage, including the British version of spelling.
Actually, I remember reading somewhere recently that the American spelling of things like color (instead of colour) is the original spelling, and sometime after 1776 the Brits changed. America never caught up (the same way it's still trapped in foot/pound/slug measurements). I'm not sure if this also applies to the "authorised" vs. "authorized" incompatibility.
--- Always two there are: a client, and a server.
:)
A couple months ago they had and article about fractal antennas. I think they said they're not much better than regular rubber ducks.
Cell phones use microwaves to transmit their signal. This is a low powered radiation as opposed to a high-powered radiation like X-rays or Gamma rays. Microwaves have more energy than radio waves but actually have less energy in them than visible light- they're on the opposite end of the spectrum from gamma and x-rays. Your cell phone would have to be generating more power than a microwave oven to hurt you - even then it wouldn't mutate you like x-rays do... only cook you :)
I talked to a friend/collegue here at work, and here is what he said:
.. far too big and battery hungry for a handset using todays technology. Mobiles in any case require 360 degree coverage .. you can have a handset lying down standing up, in any orientation you like relative to the RBS (base station)
...(or your head) ... not smart and you would loose MANY dB ... most of the power. which removes
... IF we were using very very high frequencies. But a practical
" As is common in the US, companies sometimes make a big noise about stuff that has been known for (almost) forever. As even mentioned in the article, random and regular layouts are both tradidtional for phased array antennas,
but other layouts are also used and their characteristics are known.
However there are a number of HUGE problems before you can bury such an antenna in a handset as they suggest tand the (prototype) phone shows.
1) array antennas only effectively transmit at 90 degree to the surface. If you add it some electrical tilt this can be extended to approx a 45 to (extreme) 60 degree eitehr side of that but the circuitry to do that dynamically is VERY complex
2) That energy would need to go through your hand
the point
3) actually you can't build a phased array that small in any case, the article is just "science fiction" in the sense that it is theoretically possible
problem is that you can't have the elements of the array signigicantly closer together than a wavelength, otherwise they just couple togetherand dont act independently (and the array therefore stops functioning as an array, it just works as one antenna). a 900 MHzsignal has approx a 30cm wavelenth.
So that's that!
An antenna radiates some (or most) of its energy, and sends the rest back toward the radio. This ratio is what we call SWR. Of the returned energy, some might be lost in the feedline. The rest reaches the radio and bouces back to the antenna for "another try".
If we have feedlines that are relatively long for the frequency, we get concerned about the SWR so that our energy is not wasted heating up the coax between the radio and the antenna. If our feedline is short, then the SWR is a factor if it raises the voltage high enough that the reflected energy bothers the radio. That can be really exciting if you are looking at hundreds of watts, but should not be a factor with the low power levels we are contemplating here.
So if our feedline is short enough, as is common with handheld radios (and cellular phones are radios, of course), our antenna is going to be radiating nearly 100% of the power. It is like the "efficiency" of an electric heater - an electric heater is ALWAYS 100% efficient.
Perhaps the authors really mean that their antennas can direct the radio energy in a more useful direction, such as horizontally. Often this is exactly what we want, and we already have antennas made just for this (such as a vertical dipole). If this is what they are getting at, I did not see this in their report.
A dingo ate my sig...
There may be things to worry about, but modified brain cell DNA isn't one of them. Brain cells don't divide, and then it doesn't matter much.. the problem is with organs that divide all the time, or if you force them to divide by damaging them. The liver is particularly eager to let its cells start dividing, and if their DNA has been damaged you get cancer.
TA
Yes, I heard of this a long time ago, too.
Uhh. AIUI Americans speak the way they do because a lot of the original settlers came from areas of Britain which had (and still have!) accents which sometimes sound more American than English.
Or so Bill Bryson says, anyway (which is about as much linguistics as I'm prepared to read, since it's funny too :)
No; the statement is accurate. The RF RADIATIVE efficiency is 25% greater than that of a standard stubby. The ComCyl stubby and cell phone act as antenna which together virtually achieves the efficiency of a dipole--which itself is virtually the same as that of a cell phone with a 1/4 wave whip.
No hyperbole her. No magic,no new physics. Just a great antenna design replacing a poor (coil stubby ) one.
Cordially,
Nathan Cohen, Ph.D>
It is like the "efficiency" of an electric heater - an electric heater is ALWAYS 100% efficient.
Not really. An electric heater driven by alternating current may waste some energy by creating a variable magnetic field. (I.e. when the heater is a coiled resistor wire.) Not a big problem for ordinary heaters though.
Are you suggesting that the only function of DNA is to guide cell division? It's not.
DNA is quite literally the assembler language for life. The code on the DNA is used continuously by the cell for ongoing physical processes.
Broken DNA leads to broken proteins. This is extremely bad juju in a brain.
It was a joke! When you give me that look it was a joke.
If so, one could easily use a laser printer to print a fractal of their choice onto that blue press n' peel material, iron it onto a copper board, etch away, and have a highly detailed fractal antenna for cheap.
Might be something worth trying.
i think i read about this fractal antenna idea
quite a while ago in Discover. maybe it was SciAm
again, though.
dillie
thank you very much to the moderators who stand by daveo and reespect his right to post piecefully without bothering anywon!!
-DAVEO
http://www.fractenna.com/wpintro.html
"A Fractal Antenna will NOT provide a VERY SMALL SIZE WITH VERY BROAD BANDWIDTH."
"A Fractal Antenna will NOT PROVIDE HIGH GAIN, VERY SMALL SIZE and BROAD BANDWITH"
"A small Fractal Antenna's field strength is NOT (as it is called elsewhere) `STONISHING' (sic)."
"THERE IS NO EVIDENCE THAT FRACTAL ANTENNAS PROVIDE FREQUENCY INDEPENDENCE"
"A Fractal Antenna will NOT provide an efficient radiator when VERY electrically small."
Check out this related article:
http://www.eetimes.com/story/OEG19990617S0014
PS: I once gave up my land phone for a PCS cell phone. I then gave up my cell phone after finding that my face was warm and tingly after 30 minute conversions.
The Brits took on their affectations of pronouncing things the way they do now around 1750. The Dutchess of Devonshire (figures, some rich aristocrat with nothing better to do) didn't like the way people sounded and started the English accent as we know it today.
Bill Clinton: Pimp we can believe in. - The Shirt!!!
Yeah, well, "sort of". There are three "media" to consider - the output stage of the transmitter, the feedline to the antenna, and the antenna itself. Standing Waves (the S W in SWR) are caused by an impedance mismatch at these transition points. Thus, not all of the energy the transmitter generates actually gets to the antenna to be squirted into the ether. Energy "lost" in the transmission line is just good old "ohms law" losses caused by electrical resistance.
This gets worse as the frequency gets higher - caused by the "skin effect" - only the outer part of the wire (or whatever) carries the electrical energy.
The other thing about antenna efficiency is that the antenna itself cannot increase energy - efficency of so called "gain" antannas is generally because they focus the transmitted energy in a particular direction, rather than spreading it equally in all directions.
What the antenna mey be able to do, with the great number of radiating elements, is effectively transmit with a mixed polarisation - so when the signal bounces around (line most cell phones signals do) there is still sufficient component with a polarisation that matches the antenna at the other end.
Still, an interesting concept. Ken
I suspect they mean 25% more efficient for RECEPTION. (i.e. given signal strength X they pick
up a 25% stronger signal)
A good thing if yer trying to receive sat signals (i.e. for built in GPS) or in areas where cell coverage is weak.
-- -- The Dragon De Monsyne
I wonder how many iterations the antenna in question uses?
More Iterations= Lower *average* segment length.
The idea is ingeneous, tho. There are wire (or plate) segments of quite a few lengths and widths in the image shown. This should mean that individual parts of the antenna would work best at different frequencies. Perhaps a better spread-spectrum antenna has been born?
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Whizzmo
...and tesselate the Sierpinski (sp?) triangle onto a, say an icosahedron? Many-directional antenna!
nuclear presidential echelon assassination encryption virulent strain
Whizzmo