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Old Geek Invents New Stick
the morgawr writes "According to the EE Times and Science Blog, a scientist at University of Rhode Island has developed a new type of antenna design that, by increasing the efficiency, performs as well as the convential quarter-wave design but is only 1/3 as large."
To check his theory, Vincent analyzed and compared the current profiles, output power and a score of other standard tests for measuring antenna performance. All measurements were in reference to comparative measurements made on a quarter-wave vertical antenna for the same frequency, on the same ground system and same power input. "I was able to increase the current profile of the antenna over a quarter-wave by as much as two to 2.5 times," said Vincent.
As a ham (amateur radio operator) this sounds like a very exciting development. I would like to see more "real life" testing in a variety of settings. Still, the idea of an antenna that can be reduced in size by that much (2/3) comes in very handy on the low bands where it's not uncommon to use several hundred feet of wire (Usually into a tuner).
Happy Trails!
Erick
http://www.busyweather.com/
Can it be adjusted to fit on top of my tinfoil hat?
"performs as well as the convential quarter-wave design but is only 1/3 as large"
Behold! I give you the twelfth-wave design!!
How does it compare against that bizarre antenna developed by genetic algorithms that we saw a story on a few months ago? Or am I comparing apples and oranges here?
-1, "1337" speak
Will we see this at next year's WiFi Shootout?
Kinetic stupidity has a new brand leader: Allen Zadr.
Once again, it's been proven that it's not how big it is, but how well you use it.
Crushing dreams at the speed of sarcasm
this is patents at their best: the little guy innovates, and becomes the not-so-little guy in reward
that should be the purpose of patents, to protect the little guy who innovates
let us hope that we can back to this world, a world where patents reward innovation, instead of suppress it
it is a delicate balance, but there are hordes of ip lawyers and corporate whores out there who are hard at work, having sold their conscience, hard at work warping the balance in the direction of those who don't deserve to be rewarded for suppressing true innovation like this
intellectual property law is philosophically incoherent. it is your moral duty to ignore it or sabotage it
"With the new helix design, Vincent has built a prototype 7-GHz antenna that he claims is indistinguishable from a quarter-wave antenna in all but its size. "Because the new design is completely planar, we could crank these out using thin-film technologies," Vincent said." Sounds like the answer to radio -powered smart cards ios just around the corner?
All i could see is that it is a 2-dimensional helix, so it's likely to be directional, if radio waves aren't hitting it on the perpendicular they will miss.
The other thing I saw was that you tuned the antenna for a frequency with components - does this mean potentiometers or does it mean scrapping it and buying another 2d helix tuned to the specific wavelenghth?
I still wouldn't mind seeing these in cars. My only question is if this can work with cars tha have "in windshield" antennae, such as mine.
Hmmm... I am no expert, but I thought those AM towers were tall so the antenna could be placed at the highest possible altitude. The radio transmitters in the Philadelphia, PA area are also located in the highest place in the region geographically.
I think the actual antenna is attached to the top of the tower. It's not the entire tower. Can someone help me out here?
Remember... ZG9uJ3QgZm9yZ2V0IHRvIGRyaW5rIHlvdXIgb3ZhbHRpbmU=
effect in the radio industry, where finding areas to put antennas is difficult due to population density, FAA regulations, etc. A more compact unit could be placed on taller buildings, essentially broadening the area that the signal could reach in urban areas.
Don't be a looter...and yes, I know that it's spelled with an "A" instead of an "E".
There are several parameters for an antenna system (receive parameters in parens):
Most compact designs trade bandwidth for performance - the work well at f=NNN.N MHz, but not well at f=NNN.N +
This gets to be REALLY important for wide band systems like CDMA and UWB.
www.eFax.com are spammers
That the University of Rhode Island and the Physics dept were made beneficiaries of the patent.
I can see this generating alot of revenue, and people (corporations) that may try to rip this off.
At least they will have a vested interest in fighting for the patent.
He found that by using those pringles mini cans, he could get similar reception to that of a regular-sized pringles can.
He expects to get a 10x power boost from metal chewing gum wrappers, and 50x from a microwaved AOL CD!
stuff |
c'mon, i don't care what you say... if it's 1/3 as large no woman on earth would believe it performs as well! :p
Well, nice, but is it better than fractal antennas, i.e. Sierpinski antennas?
I was just reading about something like this just last night.
I'll bet it ends up working on the same principle that Bill Beatty is talking about when he got to thinking about why it is that an atom can absorb light so readily even though the size of the atom is such a small fraction of the wavelength.
Relevent articles:
Energy sucking antenna
On the Possibility That Electromagnetic Radiation Lacks Quanta of Any Kind
Nearfield coupling and tuned circuits
..this will be great, living in the stix has it's advantages and disadvantages (disadv-no cable broadband , adv - can see the stars at night) Disadv -Having to rely soley on Direcway for broadband. This will open the doors also to companies wishing to move to the rural areas.
A bunch of Tech Stuff
IBM, Cisco, Microsoft or any other tech company can steal this patent by filing something akin to the following.
o ugh and/or showed it to you first, if you jack it up to a computer, then you've got a patent pal! Now no one can connect a computer to this device without giving you money! Yippie!!
"A Method for reducing the size of radio antennae by a quarter using new design UNDER THE CONTROL OF A SOFTWARE DRIVEN DEVICE."
Remember, even if someone else has patented,invented,used,implemented,sold,issued,th
Welcome to the US patent Office. Where dreams CAN come true!
May the Maths Be with you!
I wish them well but FWIW, it got a skeptical response on this popular ham site qrz.com
I'd love to see a picture of this as I don't know much about antennae.
Here.Smaller is nice, but if we build a cell phone with a DLM the same size as the antennas in current models, can we get 3 times the reception?
"We reject as false the choice between our safety and our ideals." --The American President (20.1.2009)
Although the articles are a bit thin on specs my gut instinct tells me it will be similar or an improvement the EH antenna. Link to definition (pdf) of EH antenna Link to (pdf) how to build an EH antenna.
I hope that despite of the patents the design will be made available for amateurs to use and experiment with.
These kind of innovations just show that Amateur Radio is still alive and can contribute in the advancement of radio.
Amateur Radio also still works for emergencies.
73 de Sjaak, W4RIS ex-PA3GVR
Hmmmm.. a 'ham' making new antenna discoveries...sounds familiar:-)
It is not physically possible to attain a moderate Q or low Q, thin monopole --antenna-- which is 15-18 inches on 21 MHz and is efficient. This is not a statement against K1DFT, or anyone else. It is a statement of fact, based on the physics of very electrically small antennas, and many years professionally devoted to pursuing such issues. K1DFT has apparently pursued a path long since traveled by many others, and not only myself.
Occasionally, in some form factors, it is possible to trade efficiency for gain, but this is too short for that. And so much for bandwidth.
Great care needs to be taken to remove multipath effects in the measurement of gain, and greater care needs to be taken in equating measured comparitive gain with actual antenna efficiency. Based on this anecdotal report, there is no evidence presented that such issues could be removed in the measurements.
Radiation resistance results from an antenna's sampling portions of radiating waves. A short antenna samples a small portion of the wave--and not from the peak, unless the electrical length is 1/4 to 1/2 the wave or more. Multiple current maxima do help increase radiation resistance. Efficiency is derived from the ratio of this radiation resistance to the total resistance--which includes ohmic losses. Distributed discrete loads are moderately lossy, and one would require load Q-factors of 1000 or more to attain even moderate Q antennas with high efficiency.
The optimization of distributed loads in monopoles is an old technology, recently aided via genetic algorithms. I recall, for example, some good work on this approach published in 1996 by Boas et al. Before that, R.C. Hansen made fundamental efforts into such understanding, as well as others. MATLAB is also a poor tool for this, because it is difficult to assess losses properly.
Another concern is: what is radiating? In some cases, ground planes (counterpoises) do, indeed, radiate in the far field and are thus part of the antenna. The monopole 'antenna' is often a loading mechanism in this case, and contributes little to the radiation. There are commercially used 'antennas' that are 1/10 th the height of a 1/4 wave or less; are broad/multiband/ and so on. This is not new. They are used in wireless LAN; RFID; and cell phones; and many other places.
Many here are aware of my efforts in fractal antenna technology--which started in a similar radio amateur vein. Although I applaude continued efforts into antenna experimentation through ham radio, I must confess that my educated opinion is that nothing new has, or will be, attained by such efforts. The state of the art is often not public, and far outstrips what is commonly available in, for example, amateur radio publications. I would enjoy being wrong, however. In fact, I'd get a great kick out of it.
It's sure fun to read about though, and experimenting is fun to do.
Again, I'd like to see the plots. Extraordinary claims require extraordinary proof, and three simple plots - VSWR/freq, radiation pattern in XY, radiation pattern in YZ - would go a long way to answering my questions.
www.eFax.com are spammers
I'm sure that there must be something close to his design on the ARRL site. After mulling it over coffee, I thought of the endless "hide your loaded helix antenna as a flagpole!" QST articles over the years. (Yeah, most flagpoles have coax cable running to the house. No one will suspect a thing!) D'oh, most of the articles are members only.
One line blog. I hear that they're called Twitters now.
No, not another patent flamefest. Just that I wanted more details than the articles provide, but I can't seem to find the application. Anyone else wanna try?
echo 33676832766569823265328479713269.8639857989Pq | dc
From the simplistic description given, this design has hundreds of thousands or prior art examples already sold in the marketplace, and has had for maybe 45 years.
Most any CB'er that wasn't running a full 1/4 wave stick on the roof of his car, and getting it mangled by driving thru any overpass with less than 14 feet of clearance, was using a shortened antenna of this design. They were also a bit narrowband, having extreme difficulties in getting 1.3/1 or better vswr performance over the 40 channels of the cb band.
They alsa radiate a disproportionate amount of their power well above the horizon, reducing the gain in the real world.
New? Yeah, somewhat like me, I'll be 70 in a few months.
I suspect that there are, or were (some having gone on to that big retirement party in the sky held for failed companies or merged into oblivion entities) plenty of patents that will prove prior art, if the patent office wasn't too understaffed and lazy to search for them. Avanti & HiGain are just 2 names that come to mind.
Scuse me while I chuckle at yet another of the patent offices incompetant blunders.
Cheers, Gene
When the ionospheric conditions are right it is possible to work (on 28 MHz, at least) the entire world with a 5 Watt FM transceiver. Very spooky!
Most amateurs use way too much power anyway.
KI3J
Groan. This is not as unique as most would have you think.
First, most PCS phone antennas don't have to be shortened. The wavelength is such that it's not hard to get 1/4 wave across your typical portable phone. It's a mere 4.1 cm.
Just so that most of you understand, a monopole antenna is really half of a folded dipole. It has a wire going up and then it goes back down the pole to a field of radials. It has a characteristic impedance of half what a folded dipole would be --about 150 ohms.
In contrast, a normal quarter wave vertical has a characteristic impedance of about 37 ohms (assuming a very good radial system).
Now, remember the part about heating up the antenna? The reason it happens with very short vertical antennas is because there is a current node right there at the base feedpoint. Even a small amount of resistance will generate heat. As you shorten the antenna the characteristic impedance drops. For anything less than a tenth of a wave long, it can drop to less than an ohm. At that point, ANY antenna resistance, even the normal resistance of copper or silver, becomes very relevant. If someone were to use a superconductor, it might make a very big difference.
So a shortened vertical isn't such a good deal. We use them because sometimes that's all we can afford to install on a mobile system. This is why most hams who operate on longer wavelength bands try to locate the loading coil closer to the middle of the antenna. It gets the loading coil away from the worst of the current node, reducing i^2r losses, and increasing efficiency.
Now, take the monopole: The current node is near the top of a quarter wave monopole, not the bottom. We still need a loading coil, however, so that we can match the impedance to something we'd expect a transmission line to have. If we shorten the monopole, we move the current node. The key is to move the current node away from the loading coil, because loading coils don't radiate well.
Thus, what this designer has done is to distribute the loading coil of a shortened monopole so that he avoids the current node.
There are problems, however. First, you still need an effective radial system. Without one, you simply won't have anything that radiates worth a damn. Second, while coil Q factor is less relevant where it stays away from the current node, it still has to be damned good. Further, the current node at the top needs to have very good surface conductivity.
Finally, no matter what, a shortened vertical antenna will have a shortened bandwidth, proportional to how much the antenna itself is shorter than a regular 1/4 wave. TNSTAAFL.
Don't misunderstand, a short antenna doesn't have to be inefficient. However efficiency is not the same thing as gain. Short antennas can not have much gain. That's a matter of physics and mathematics. And the shorter an efficient antenna gets, the less bandwidth it can cover. Despite the steady parade of publicists, that's the reality. Don't buy any snake oil, folks... This isn't really that novel.
Nearly fifty percent of all graduates come from the bottom half of the class!
"As others have noted, the tower is the antenna. The output line coming from an AM transmitter is fixed directly to the tower. Usually this is not fixed at ground level to avoid killing a passerby. RF waves WILL arc and kill. Also, if you are feeling especially depressed and want to cause yourself bodily harm, walk up to a hot AM tower barefoot and grab it."
:)
When I was in the Canadian Military I was a Radio Operator. We had a standard practice of informing the operator not to key the antenna when changing the HF antenna on the top of the truck - usually in fact the person doing so went in and physically checked the antenna was disconnected at the set end. Then you went on the roof and unscrewed the antenna and screwed in the new one. If someone forgot the middle step - and the operator keyed the antenna - you would see the person touching it get lobbed a good 10-15 feet off the top of the truck by the shock and it might or might not kill them or at least severely injure them. Only saw this happen once, and the guy wasn't hurt, he got up and was ok in a few seconds - although the operator was hurt shortly thereafter
10,000 watts is not a good thing to run through the body...
"The first time I got drunk, I got married. The second time I bought a chimpanzee, after that I stayed sober" Arian Seid
The "gain" of an antenna comes purely from directional effects, in a transmitter, which is easier to understand, more of the radiation goes out near the horizontal, where it is useful, the apparent gain in receive mode is identical due to the reciprocity theorem. In any situation involving electromagnetic radiation, such as light, or even pressure waves such as sound, the directional properties are always limited by the dimension of the antenna, loudspeaker, lens, etc, in the case of a verticle monopole you really need height to get lots of low-angle radiation, for the same reason that radio telescopes of high angular resolution have several dishes spread out over a great distance, sometimes hundreds of miles. It is also why a 15 inch PA loudspeaker will give, on axis, maybe 102dB at 1 metre with 1 watt input, while an 8 inch hi-fi speaker may give only about 80dB. even though both are equally well made and have had similar attention to loss mechanisms. Likewise the best searchlights have large-diameter lenses....A human eye is large in comparison to the wavelenght of light, so it can resolve lots of detail, the eye of an insect can distinguish only vague impressions of light or colour. There are lots more examples.
Some years ago, the Crossed Field Antenna, which purported to be even smaller, made similar claims, backed up by real-life tests.... I am sure that Google will find lots of references, so why does every AM broadcast station not use one? Maybe 10 to 20 feet high, not too heavy, no expensive materials, yet do you ever see them? Again, it was correctly resonated, but it did not have the height.
In any case I am sure there will be a very large amount of prior art on this one, a fair proportion of CB antennae for instance use loading coils and helixes in just about every combination imaginable. The current distribution of monopole antennae has been widely studied for many years. I would like to see a picture of the thing, to see what, if anything, is new.
Also, the microwave end of the spectrum has no need of smaller antennae, no mobile phone I have seen in recent years has had an external antenna at all, and you can only make a phone so small.. You have to hold the thing, after all. If it is not entirely self-supporting in air, dielectric losses will be serious.
Granted, I have seen antennas that defy logic until you really understand how they are working.... the Discone antenna for example... but this one still is baffling and the lack of details increases the skeptical thoughts.
It sounds like a cross between a capacitive hat and a rubber-ducky style helix.
A capacitive hat lets you expose the lower part of the 1/4 wave half-dipole (where most of the current is) then cut off the end. The remaining current goes into the capacitive hat and doesn't contribute to the magnetic field radiation.
A helix lets you shorten the entire half-dipole, but still ends up with the current decreasing in the classic cosine fashion as you go up the whip, until it goes to zero near the end.
This sounds like some cross of the two, with a variable wind and a distributed capacitive loading, which allegedly succeedes in keeping the current high (and in-phase) over the full length of the shortened half-dipole.
I'd love to see a better description than the one that was given.
Meanwhile, I'm suspicious of the claim that it is just as good as a dipole. If it's shorter, it's intercepting a smaller amount of the passing wave. To achieve equivalent gain it has to make up for that in some way (like being effectively broader, or the "capacitive loading" structure on the upper end of the device coupling to the electric field in the space beyond).
= = = =
By the way: My favorite "shrunken antenna" is the DDRR. Very narrow band, but tiny.
Bantam Dominique roosters crow a four-note song. Once you've heard it as "Happy BIRTHday" you can't NOT hear it that way