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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.
will just think this means they can be identified and tracked from twice as far away.
Do not try to read the dupe, thats impossible. Instead, only try to realize the truth
What truth?
There is no dupe
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.
Buy Steampunk Clothing Online!
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?
worst headline ever!
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
performs as well as the convential quarter-wave design but is only 1/3 as large
I figured it out! It's 1/12-wave antenna!
Failing to learn from history dooms you to repeat it.
..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
"The technology is completely scalable: Take the component values and divide them by two, and you get twice the frequency; take all the component values and multiply them by two, and you are at half the frequency," said Vincent.
That's been known for quite some time.ahh, so now you don't have to cut as big a whole in your fruit...
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)
umm .. I realize that the stuff we call physics used to be called magic, but this sounds like hokum to me. There have been a number of people who've pooped out weird "e-h" antenna designs .. the problem is actually getting them to work in real life installation scenarios. Caveat Emptor! (sp)
pictures and some details would be nice... it's rather hard to believe the claims without seeing what this thing looks like or the results of tests.
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
While I'm not an antenna physicist, I've been a ham radio operator since 1958 and have built and used a LOT of antennae. I've discovered that there are trade-offs. I will be very interested to see how this pans out and hope that it is, indeed, a break-through.
Here are some of the reasons for my skepticism. An antenna that is smaller will inherently intercept less of the signal when used for reception. It's called capture area. When used for transmission there are usually reductions in efficiency due to increased losses in the components that are used to reduce the size. Other trade-offs often appear in the form of directionality, that is, the antenna radiates/receives better in some directions than others.
In the professor's blog, he mentioned that when he increased power to 100 watts at 21 MHz, the antenna melted. That means that energy, instead of being radiated, was converted to heat, AKA lost efficiency.
I have operated successfully with relatively small antennae and low power on the shortwave bands for a long time. My typical mobile setup is 4 watts at 14 MHZ to an antenna on the car trunk that's about 4 feet tall, a commercially made Huster brand with a 22 inch base section for those who are familiar with ham antennae. Using that setup, I, too, have made good contacts on all continents from the central US. As the old saying goes, you can make contacts with a wet noodle for an antenna if the band conditions are good.
Anyway, that's my take on it. I hope that I get a chance to try out one of his creations on the shortwave bands. It sounds like, if it works as billed, that it would be great for my mobile operation.
73 and "Do the Right Thing. It will gratify some people and astound the rest." - Mark Twain
"Do the Right Thing. It will gratify some people and astound the rest." - Mark Twain
Was especially amusing.
"Old geek invents new stick"
Well at least I thought so.
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.
I was kind of hoping for design specs myself. Not that I would go out and build one, but I wouldn't mind a peak at the technology.
But as I read the article, the guy looks like he wants to make a few bucks from his discovery before providing info/pictures/etc..
Why else would you patent it?
"Imagination is the only weapon in the war against reality." -Jules de Gautier
What kind of towers are you checking - cell, LMR, broadcast, Ham?
Perhaps you'd used gear I've designed?
www.eFax.com are spammers
With most cell phones, especially CDMA, power is very carefully controlled. I seriously doubt that an increase in antenna efficiency would cause problems with current installations. Basically, the phone would just input less power to the output PA and get the same EIRP. On the receiving end, it would just look like a better connection. Cell phones already know how to deal woth signals from multiple basestations.
(S(SKK)(SKK))(S(SKK)(SKK))
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
10W - Reached a station in Chile. Was he in Rhode Island?!? I'm assuming he was but hot damn that is pretty good.
What is up with the website? It seems like it would be a great blog to read but there are 3-5 pop ups per link. That sucks.
Credit to the inventor too, who freely acknowleded URI for supporting his efforts. I don't know if he had to sign away IP rights to the University like most corporate folks do, but it *sounds* like he's including them as partners without anyone having to remind him of a certain signature on a certain piece of paper. Credit where credit is due.
I'd say that depends greatly on the size of your wave...
...to be a "scientist". You only need to be educated (in whatever way you can cram knowledge into your brain), and follow the scientific method.
Sorry if you felt that was out of context. I know from a lot of practical experience that adding "Loading" to antennas means adding inductance to compensate for reduced length. Adding inductance means adding coils which are inherently lossy, both resistively and dielectrically. The loss can be mitigated by using larger conductor and better dielectric materials as insulation, but there are obvious physical limitations to that and, in addition, the effect of increasing the "Q" reduces the useable bandwidth. From my reading of his articles it sounds like a key component of his design is a helix and a loading coil. "but I've been able to put a combination of them together to create a revolutionary way of building antennas. It uses basically a helix plus a load coil." I've used a number of antennae with distributed loading and they work, but are definitely a trade-off as compared to a full sized antenna.
I honestly am not trying to rain on his parade, especially as a brother ham radio operator. I will be very interested to see the details of his design when they become available and hope that he has, indeed, found the "Holy Grail" of antenna design. If he hasn't found it, then I trust that his work will, at least, be a step toward it.
"Do the Right Thing. It will gratify some people and astound the rest." - Mark Twain
"Do the Right Thing. It will gratify some people and astound the rest." - Mark Twain
I don't know what story you're talking about, but perhaps you're thinking of the results in Linden's thesis on GA-optimized antenna design (maybe by "bizarre antenna" you mean his crooked-wire design)?
- The top post said it first, mine was a follow-up
- The two antennas are, well, antennas. Apples and Oranges are both, well, fruits. The same yet different. It's a perfect analogy, because they are similar.
- The link you show complains that an apple/orange comment precludes comparison, yet, my post did make a comparison between the two technologies.
- I believe the site at the end of your link is full of shit, and most people do not use the apple/orange analogy with such a closed mind-set.
--Allen Zadr (A.C., due to counter trollism)
Unfortunately, we often confuse physical laws and longstanding assumptions. Sometimes it is one of those over-the-shoulder questioners who can tell the difference.
This could well be snake-oil. Anyone recall the CB craze of the '70s and the antennas that were sold to the gullible?
Hams will certainly question, but if there is validity in the design, you can bet that it will be improved and made functional. The only despicable response is to say "It is impossible, and I don't want to hear another word about it!"
NH,
I understand that you don't mean to diminish Mr. Vincent's accomplishment by pointing out that he's not a scientist in the bona fide sense of the word, but your comment makes me question (strict dictionary definitions aside) where the line between inventor and scientist is drawn?
Perhaps I should read the article again, but I don't recall seeing Vincent mentioned as a "technician", only "employee". Given that he filed a patent for his invention and has stated that he intends for any resulting profits to be shared with URI, I wonder if his actions in that regard make him out to be more of a scientist than inventor?
What actually makes a scientist a scientist?
This is all fine and dandy--
but when are we going to be able to buy the fractal antennas we heard about a few years ago. They were supposed to be the bomb, and I wanted one for TV, but they don't seem to sell any consumer models. What up with that?
Si la vida me da palo, yo la voy a soportar Si la vida me da palo, yo la voy a espabilar
This sounds familiar.... I think if you keep pushing down on it, you'll pick up alien plans to invade Hollywood. It's amazing! [scifi.com]
Yes, but that's assuming that the source signal actually reaches your destination antenna. Having an antenna of the same size but better reception might allow you to better pickup existing signals, but radio signals also have a falloff point (different for AM/FM) and penetration ratio.
I don't know about Atlanta radio, but the signal itself still have to reach Charlotte well enough for the antenna. Also, for an in-windshield antenna, you could probably just get a portable antenna and re-route the hookup from your deck if you wanted to use an alternate antenna.
These guys at AntennaWeb will have to look into this
Size does matter to women when you have an 8 foot antenna on the roof.
I always thought of Creationism as the Raving Right's version of the Loony Left's Anthropogenic Global Warming-brightmal
Hah! You say perform well but you girlfriend say NOT!
Our all-nature formula make it 3 times bigger!!Order today!
You were 80% angel, 10% demon. The rest was hard to explain. - Over The Rhine
"Math in a song is good."-Linford
The article only says this antenna is 80-100% as good as a full quarter-wave design. It will be interesting to see if this can be used in a collinear configuration for some real gain.
How long do you think it will be before Microsoft claims to have already invented this 5 years ago?
BPL will be a problem and not just for HAMs...
m 0H EP/is_3_22/ai_114533115
http://homepages.ihug.com.au/~vk5vka/
http://www.astrosurf.com/lombry/qsl-rfi-bpl.htm
http://articles.findarticles.com/p/articles/mi_
My only concern would be how "directed" this beam is. As crowd control it would probably be necessary to be able to cover a wide arc without disturbing innocent people in nearby businesses.
Kinetic stupidity has a new brand leader: Allen Zadr.
In fairness, I prefaced my first remark by saying that I'm not an antenna physicist. I do have some credentials to the extent that I have a BSEE degree and have taught electronics at the college level in addition to my 46 years of practical experience as a ham. I also mentioned my using shortened antennae for my mobile hamming. I successfully operate as low as 10.100 MHz with that same 4 foot antenna and 4 watt rig that I mentioned earlier (different loading coil) instead of the roughly 24 foot 1/4 wave that would be normal at that frequency.
I think what I didn't communicate well is that, pending more review, there are some things that I'm wondering about. It just sounds, to this admittedly old sparky like getting something for next to nothing. There have been a number of antennae in the past that have claimed some pretty impressive specs, for instance, there was a commercially manufactured dipole with a mystery sealed device at the feedpoint that claimed less than 2:1 SWR over the range of 3.0 to 30 MHz with a very simple coax feedline. Pretty impressive and it actually did meet that spec when tested, but it turned out that the sealed device was a non-inductive 50 ohm resistor that wasted at least half the radiated power, a trade-off and maybe a good one if bandwidth was important. Anyway, I await, with bated breath, the full story on this new development which I expect, at the very least, to be quite educational.
73 and "Do the Right Thing. It will gratify some people and astound the rest." - Mark Twain
"Do the Right Thing. It will gratify some people and astound the rest." - Mark Twain
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.
Note to self: check darwin awards in a couple of days.
"It's too bad that stupidity isn't painful." - Anton LaVey
Does this mean Pringles sales will go down sharply? ;)
Here's the quote from the article that made my B.S. alert go off: "And those 300-foot tall antennas for the 900-KHz AM band that dominate skylines would have to be only 80 feet high, with no compromise in performance, using Vincent's design, he said."
They seem to have forgotten the simple fact that altitude matters when it comes to antennas. If you want to increase the line-of-sight range of the antenna, it needs to be higher so it will be above the horizon at greater distances.
I have never voted for a candidate for public office that won.
Oh, you vote Libertarian too?
Is that what your momma told you boy?
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!
(If you are wondering why I say this its due to the scientific method wasn't really around till around Newton's time and heh Newton disliked the idea of the hypothesis. He wrote some quite flaming letters to reviewers of his work who called part of his work a hypothesis)
Do anyone remember the Helex Shortened Dipole.
The helexes were made with circuit boards soldered to the ends of 18 inch length dipoles.
Circa 1973.
Supra et Ultra
So the guy spends 8 years developing a SEEMINGLY new antenna technology... and what does he get? An INTELLECTUAL PROPERTY award for the patent!!! Not a technological award, but an IP award... how sad is that?
I'm sure someone has thought of a distributed load antenna before. Sure, you can get efficient radiators, but the problem with electrically short radiating elements is that you don't know in which direction the radiation is going. All he probably did here was distribute the matching mechanism throughout the antenna. Big f'ing deal. You can impedance-match just about any hunk of metal to the power source, but impedance matching isn't everything, and neither is power efficiency.
The fact that his antenna melted only goes to show that it is not efficient at all. All of that heat came from the power that was supposed to be radiated, but wasn't. Instead, it was dissipated in the antenna enclosure... that's not efficient. He was probably doing all of this testing during the recent sunspot cycle peak when all you need to talk to Chile is 500mW EIRP.
The only "invention" here is the illusion that this is innovation, when in reality all it is, is a cleverly timed experiment in tomfoolery design to patent something that is neither innovative nor even technologically sound.
I note the convenient absence of antenna plots, range data, or any substantiation that this even works... anecdotes are not evidence... under the right conditions, you can cut a hole in your coax and talk to Chile...
"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
I wish Slashdot allowed the tag. Then I could post the famous "This Story Is Useless Without Pictures" image.
Then again, if they allowed it, someone would probably have posted a picture of the thing already.
"A great democracy must be progressive or it will soon cease to be a great democracy." --Theodore Roosevelt
I have my little barn behind my house, where I build all sorts of cool projects, work on cars, and make some rather crappy software to control some of my ridiculous inventions. A good friend of mine lives about half a mile down the road, where he has his own (bigger) barn, and he works on even cooler projects, and runs a little electronic prototyping business. (When he puts those circuit boards together by hand, they come out looking like they were professionally assembled by machine.) The thing is, he doesn't have Internet access over there. I have DSL. (He's over the county line, where they don't have DSL.)
We came up with this idea of setting up some type of line-of-sight system to give him wireless access to my network and to the Internet, so we could collaborate easily and do our research and development together. Also, we want to have a connection from our respective barns to our respective houses, so the kids can have Internet as well. One of the requirements we had was to make it directional so that nobody could "wardrive" over here and tap into our system, unless they got in the way, which would be kind of hard, considering it's in the middle of this field of corn (or soy, depending on the crop rotations).
Our biggest problem so far has been to get a reliable signal, so up until now, we've been running these really long ethernet cables across the field. (These cables go a surprisingly long distance and still work.) Problem is, they get damaged every so often, and it costs a lot to fix them each time. I have cables running across my yard into my house, too, so my kids have the 'net. It's a funny thing, how we set up this network with all kinds of firewalls and stuff to separate the various areas from one another. But anyway, while we do have a connection now, we are still researching new ways to do it with wireless... He had this crazy idea of using lasers, but I don't know how we can make a laser light turn on and off rapidly enough to transmit a signal at a reasonable speed. (We want audio and video conferencing, plus the possibility of transferring big data files around while we're doing that. Obviously, we need a lot of bandwidth between our two houses.)
I'm happy this story appeared here because this could allow us to get the job done without interfering with anything else... Someday, maybe we'll have it perfected to the point that neighbors around the country will connect their homes together in a sort of grid that will increase the overall bandwidth, speed, and resiliance of the Internet.
It's difficult to tell if it has distributed loading or mid-point loading,
Speaking of antennas...I was thinking about WLAN the other day and I figured that using directional antennas we could:
1) Reduce collisions (higher throughput)
2) Increase range/reduce power consumption (broadcasting in all directions takes more power than directed casting)
3) Avoid having to adapt to the slowest node (802.11g running at 11Mbps because there's one 802.11b node)
So how come WLAN doesn't use directed antennas?
Please correct me if I got my facts wrong.
Friends don't help friends install M$ junk.
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.
Couldn't find a pic
He is not a prof, but a tech.
http://www.phys.uri.edu/people/rob.html
Robert Vincent
Electronics Technician
Maintaining all the electronic equipment in the department and assist the professors and students in research activities at the Physics Department.
Personal Interests: Bike riding, saltwater fly fishing, Amatuer Radio, and restoring and fixing up old radios.
Also, the original press release. http://www.uri.edu/news/releases/?id=2659
Used mathcad also...
ee
Antiquated competence won't be a job skill forever.
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
YOU SLASHDOTTED MY SCHOOLS WEBSERVER http://zeppole.uri.edu/mrtg/jonnycload.html
Great hopefully this tech can make it's way to wireless networking and cell tech...
I don't think that you'll see superconductor antennas, anyhow, because as I remember, the superconductor would have its superconductivity destroyed the moment you started releasing radio waves. So if you designed a superconductor antenna, it would simply be so that it could keep total radio silence until the moment you wanted to broadcast. Not too bad an idea, at that, except that the cost would be $100k for the superconductor (with high vacuum system attached), and then more to run it.
Correct Horse Battery Staple: 72 bits of entropy. Enter "Correct H" into google. When it generates the phrase, that's
What I want to see is the results from the one of the "other standard tests" the article alludes to: field strength measurements. These can be compared to the known performance of a standard 1/4 wave monopole. That is what will convince me, and is what the FCC requires for broadcast stations.
Efficient short antennas have been made, but they aren't easy. In honor of the current Slashdot poll, see WWVB's antenna. This system attains 65% efficiency at less than 1/40 wavelength.
Although it is OT, I know people in my area who have used lasers to link their wireless network together. If you have 'direct' line of sight with your neighbor, then this should meet your security needs.
First, RONJA:
http://ronja.twibright.com/
"Ronja (Reasonable Optical Near Joint Access) is an Free Hardware (like Free Software) project of optical point-to-point data link"
Is DIY, and will get you 10Mbps as far as 1.4 Km. Seems like a good project to collaborate on with your friend.
Or if you have money to burn, you can always buy a "free-space optics" laser head from these guys, who have gear that goes over 1Gbps
http://www.laserbit.net/
Cheers!
John