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Using the Terahertz Spectrum for Wireless Communication
holy_calamity writes "A first step to allowing wireless data transfer over a currently unused part of the electromagnetic spectrum is reported in New Scientist. Terahertz radiation exists between radio and infrared. A new filter created at the University of Utah can filter out particular frequencies, a prerequisite for using it for data. The abstract of the paper in the journal Nature is freely available."
10 years? Anyone?
I regularly work with equipment that produces signals up to 50 GHz and let me tell you... components get much higher in cost the higher in frequency they go. a 3 foot 40GHz cable can cost hundreds of dollars and a 100GHz connector can cost a thousand dollars or more on its own. I imagine that producing and transmitting signals in the terahertz range is not economically viable for most companies.
...so communication would have to be rather short-haul as in LAN.
Perhaps TFA should have mentioned that.
Wait...
micrwave frequencies are usually considered to be the upper end of the radio frequency spectrum... the former being about 1G-300GHz, and the later covering 3Hz-300GHz.
Basically it says that putting the holes in a fractal pattern give much better results than holes in more 'normal' pattern. The rest is Calculus explaining how they can generate patterns that are really good at transmitting a certain frequency.
Sounds really interesting. I wonder if any of this applies to antenna design at average RF.
The microwave spectrum really ends at about 30 GHz, with the frequencies from 30G-300GHz called millimeter wave, and those from 300 GHz up called submillimeter. Terahertz technology is quite in its infancy. There was a terahertz conference last week, so the office I work in was pretty well cleared out. (I work on spectrometers that use what we consider low frequencies, The other thing about terahertz waves is that they behave quasi-optically, being focused by teflon lenses and blocked by cardboard. So it's not a radio band that one would use for cellphones.
The determined Real Programmer can write Fortran programs in any language.
Which is EXACTLY what TFA said...
But hey, what do I know, your post is a +5, so it must be somehow insightful, not 100% redundant.
Slashdot gets worse every day... Pipedot: News for nerds, without the corporate slant
Are you kidding? you can't do first post if you RTFA!
The determined Real Programmer can write Fortran programs in any language.
It's not strictly true that you need to have bandpass filters to transmit information. There are other ways to select individual users without frequency division multiplexing. For example:
The gotcha is that you need some way of sampling the band. One way is to to use a bandpass filter, mixer and slow sampler. Another is to directly sample (using RTDs???) or in the case of UWB just detect pulses. Bandpass filters are the conventional way of doing it, but not the only way.
...)
Ahhh, much better.
And now, a PSA from David Lynch.
For the uninitiated, that is Nothing Really Amazing in Outerspace - Alien Life My Ass.
Karma police, arrest this man. He talks in math. He buzzes like a fridge. He's like a detuned radio.
The other thing about terahertz waves is that they behave quasi-optically, being focused by teflon lenses and blocked by cardboard.
So we can finally ditch the tin-foil hats for cardboard hats? About time!
Does it make you happy you're so strange?
This is trivial. At Starfleet Academy, surface plasmon polaritons and Fano interference in quasicrystals were on our freshman exams in the first week. Even WESLEY got it right, and he was the dumbest one in our class. Well, except for that guy, George Bush VIII. I don't know how he got in, except his father was like the king of some country named Texas or something. All he ever did was exotic drugs, until the day he blew his testicles off in chem lab. Thank goodness for modern transplant technology.
Terahertz research would seem to me to be a step in that direction, by bringing existing EM modulation techniques closer to that spectrum.
And, in the end, we're not going to want to stop there. We're going to eventually want to extend application of understood techniques to the UV bands and beyond.
It may not be effective for communicating in atmosphere, but it'll eventually be a great high-bandwidth solution for intercraft and interplanetary communications. The smaller you can make the parabolic dish, the easier it becomes to effectively focus the signal.
tasks(723) drafts(105) languages(484) examples(29106)
or... it could be for Atacama Large Millimeter/submillimeter Array - National Radio Astronomy Observatory :P
http://www.alma.nrao.edu/
Google can be your friend too.. .
oh no.. not petahertz... then we'll have those animal rights crazies demanding we let it go..
there are doorways I haven't opened, and windows I've yet to look through. Going forward may not be the answer..
Ooo my bad, looks like Google was lying to me so would be his friend.
guess i should read things before i reach for the Ctrl-C Ctrl-V
Patents!!!
P.S. - Mod me insightful.
Under the influence of Post-Cyberpunk Gonzo Journalism
Actually no; terahertz rays can go through wood, sheetrock, masonry, etc. (but not metal or water).
>;k
All the better if he's dead on, that just saves the rest of us from having to RTFA!
Another example of how the tabloids (Nature & Science) publish things that have been known for ages... There seems to be a trend that you can get anything published there, since the peer review is done by totally clueless physicists who do not know anything about the state of the art.
The concept of making filters by cutting holes in a sheet of metal has been known for ages. Using periodic (or in this case quasiperiodic) metallic patterns is called Frequency Selective Surfaces (FSS). There are numerous books and tons of publications in IEEE transactions, etc. in this area.
I did etched FSS filters for 375 GHz around 1982, and the concept was already pubslished in books by then.
Old stuff. Too many scientists, too much money, too little brain.
In a way this is a pretty standard result. One can reduce the ringing in a Fourrier transform by including non-periodic sampling. What is provacative is the implication that there is some flaw in the surface plasmon interpretaion. Namely, they point to straight interference as being important rather than the constrained response of the surface electons.s -selling-solar.html
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Get solar: http://mdsolar.blogspot.com/2007/01/slashdot-user
Also, generating and modulating signals, with current technology, is done by firing very expensive lasers at very customized pieces of semiconductor materials. As for receivers, NixieBunny would know better then me what the current technology cost and noise figures would be.
All of which to say, this is an interesting article, but it's about 1% of the way towards communications in this band.
Don't get me wrong - this is a cool paper, looks like good work, and this might have some very interesting technological applications. But the perpetual question of "what is it good for?" that every reporter asks (it's got to be a law or something) about every scientific advance misses the point. We don't know what it's good for, but it expands our knowledge of the world, and that can only help us.
Using it for something is the job of the next genius. These guys did enough by getting it to work. Someone else will have to figure out what it's good for.
It's not wasting time, I'm educating myself.
... been doin' teraherz for years - it's just "in fashion" now.
Publication with some terahertz images of concealed weapons on people (towards the article end):
http://stl.uml.edu/PubLib/DickinsonDSS2006.pdf
lots of other THz articles if you chop back the URL to PubLib/
"Sounds really interesting. I wonder if any of this applies to antenna design at average RF."
yes it does.
Fractal antenna design is old news at this point.
You get a modest reduction in antenna design, but it really excels at giving you a broadband design. So it's particularly handy for UWB.
Absolute statements are never true