9 ms·
Plasma Antenna
- Zenst 7y agoHad a dig around for some pictures of such antennas and found this: https://www.researchgate.net/figure/A-model-4068-MHz-ac-plasma-antenna_fig4_286640009 https://www.researchgate.net/figure/A-model-4068-MHz-ac-plas... Find myself wishing such tech was prevalent during the early days of mobile phones and massive external aerials, but that's just the inner Jedi in me.
- segfaultbuserr 7y agoImagine a Sci-Fi title with this scene: At the last moment, some critical battlefield information is transmitted by a huge, bright and colorful beam of plasma antenna that shines the ground like Sun at night. It would make a spectacular and impressive scene of SFX and CGI, just like the SFX of the wrapped engine in the new Star Trek.. > during the early days of mobile phones Probably not a good idea, in its original form, it requires a lot of power from the mains to maintain its arc discharge, which is what turns it into an antenna, kind of like a vacuum tube that needs a constant heating power. But Wikipedia says antenna-on-chip is possible, which is quite interesting.
- the8472 7y agoEarly mobile phones were car-mounted. So if you had a nuclear-powered car a plasma antenna would fit right in.
- segfaultbuserr 7y agoAnd a tube transmitter, of course!
- rini17 7y agoThe picture does not look like arc discharge, it's more like fluorescent lamp.
- aidenn0 7y agoA fluorescent lamp is a mercury-vapor gas discharge lamp with a phosphor coating. Doesn't that qualify as an arc discharge?
- segfaultbuserr 7y agoAnd you literally need a thousand volts to kickstart a fluorescent lamp, at least on decent tubes.
- therein 7y agoLet me pull up my "flyback transformer on a chip".
- ridgeguy 7y agoNo. An arc discharge is a hot, high current density process. [1] The discharge in a fluorescent lamp is a glow discharge: low current density, moderate temperature and extended volume. [2] [1] https://en.wikipedia.org/wiki/Electric_arc https://en.wikipedia.org/wiki/Electric_arc [2] https://en.wikipedia.org/wiki/Glow_discharge https://en.wikipedia.org/wiki/Glow_discharge
- aidenn0 7y agoThe first article gives fluorescent lights as an example of modern usage of arc lighting... The second article distinguishes between glow discharge and arcing.
- duxup 7y agoI'm not antenna knowledgeable nor plasma knowledgeable. Is there a layman's explanation about what the advantages / why there are advantages here? It talks about turning off the plasma antenna, is that any different than simply not using a regular antenna? ... or what they mean by stealth or "resistance to electronic warfare and cyber attack".
- slovenlyrobot 7y agoI guess with a metal antennae you have a permanently reflective surface, AIUI once one of these are disabled they become basically radio-transparent again, which means less of a blip on radar
- Kalium 7y agoIt also means they don't receive when off, which renders them resistant to some forms of electronic warfare.
- linguistbreaker 7y agoNormally antennae are constructed out of solid materials. The plasma is controlled by electricity, so the gain characteristics can be rapidly controlled and dynamically tuned in real-time (possibly).
- bin0 7y agoSo, like the ultimate SDR?
- deleted 7y ago[deleted]
- ars 7y agoIt's related, but not the same. SDR happen after you received your signal, where you can, in software, pick different ways of decoding the signal. This, however lets you dynamically choose the antenna length, and each frequency has a perfect length that works best for it. So the two are complimentary, but at different parts of the process.
- inflatableDodo 7y agoCan someone wire one to a guitar and pair it with a rydberg vapour cell as the recieving antenna, so the audiophile community can finally have something to justify their pricing. https://aip.scitation.org/doi/10.1063/1.5099036 https://aip.scitation.org/doi/10.1063/1.5099036
- jacobush 7y agoOn the other end we have : https://en.wikipedia.org/wiki/Plasma_speaker https://en.wikipedia.org/wiki/Plasma_speaker
- inflatableDodo 7y agoGood call. Since they demonstrated 2 channel already, maybe drive that with a standard electric guitar and then have a Tesla coil driven by a bass.
- godelski 7y agoPeople just do it with Tesla coils https://youtu.be/JH-YmzZgZ-Q https://youtu.be/JH-YmzZgZ-Q
- jdietrich 7y agoThe Gamechanger Audio Plasma pedal uses a plasma arc tube to generate overdrive. It's kind of gimmicky, but also ridiculously cool - it's inherently noise gating, because the arc extinguishes at low signal levels. https://www.gamechangeraudio.com/plasma/ https://www.gamechangeraudio.com/plasma/
- saghm 7y agoSlightly OT, but there was no image in the page, so I scrolled down to the bottom and clicked a link in the "See also" section labeled "Article with image". The article had no image of a plasma antenna. What gives, Wikipedia?
- segfaultbuserr 7y agoThe picture was there [0], but later livescience.com updated the website and it's gone due to link rotting. Even worse, archive.org didn't have the image archived (but the "zoom picture" text can be seen). Wikipedia is one of the most affected website by link rotting. What gives, the Web? Donate to archive.org today! [0] https://web.archive.org/web/20081010224347/http://www.livescience.com/technology/071205-plasma-antenna.html https://web.archive.org/web/20081010224347/http://www.livesc...
- testtesttest 7y agoAnother article [0] (2007) featuring the image. [0] http://www.nbcnews.com/id/22113395/ns/technology_and_science-innovation/t/new-radio-antenna-made-star-material/ http://www.nbcnews.com/id/22113395/ns/technology_and_science... EDIT: Presentation from Igor Alexeff and Theodore Anderson (University of Tennessee): https://www.ysc.org.ua/2011/data/i.alexeff_presentation.pdf https://www.ysc.org.ua/2011/data/i.alexeff_presentation.pdf
- hawski 7y agoGoing further with the idea it could be possible to make an antenna from ionized air. As it turns out someone already patented "Antenna of ionized air": https://patents.google.com/patent/US2760055 https://patents.google.com/patent/US2760055 The patent expired in 1973.
- topspin 7y agoMeteor burst communications https://en.wikipedia.org/wiki/Meteor_burst_communications https://en.wikipedia.org/wiki/Meteor_burst_communications Meteors punch ion trails through the atmosphere that serve as antennas for various purposes.
- godelski 7y agoPeople frequently build these with Tesla coils. People also build plasma speakers, which is similar in concept. https://youtu.be/JH-YmzZgZ-Q https://youtu.be/JH-YmzZgZ-Q
- ncmncm 7y agoIt ought to be a lot easier to make this work, nowadays, with a hard-ultraviolet laser. Tune it just by pointing at something the right distance away.
- madengr 7y agoI’m betting this will have horrible noise temperature. Not good for receiving.
- Zardoz84 7y agoDid you really read it ? > At satellite frequencies, they exhibit much less thermal noise and are capable of faster data rates.
- madengr 7y agoYes I did. This is the main presentation from the reference web site. http://nebula.wsimg.com/d0cadaec2cf44c9682cebb1610ce1a91?AccessKeyId=3DA8D5B43ACC4E9632E1&disposition=0&alloworigin=1 http://nebula.wsimg.com/d0cadaec2cf44c9682cebb1610ce1a91?Acc... If you look at the thermal analysis, it is incomplete. They are only considering the thermal noise of the reflector. The noise temperature of an antenna is a function of temperature AND aperture efficiency, with the latter set by the conductivity of the reflector. Plasma is not a great conductor (compared to metal), as is shown by the nested antennas. High performance satcom (e.g. NASA DSN) not only cool the electronics, they cool the feeds also. There is another paper where they show a tube covering a LNB. Looks like some BS. I don’t see any actual measurements of noise temperature (which are very easy to do). http://nebula.wsimg.com/48f10bd80f702313a1d8d094fc7d6b01?AccessKeyId=3DA8D5B43ACC4E9632E1&disposition=0&alloworigin=1 http://nebula.wsimg.com/48f10bd80f702313a1d8d094fc7d6b01?Acc... I didn’t see any of the papers published in IEEE APS. I design antennas for a living, and this sets my BS detector off, and it did 10 years ago too. They look fine for TX (the patterns look good), but the noise data is conspicuously absent. Here is another noise analysis, but again it is incomplete. Just show some measurements. http://nebula.wsimg.com/754ac5460a5e1531953c79dd1c4863b7?AccessKeyId=3DA8D5B43ACC4E9632E1&disposition=0&alloworigin=1 http://nebula.wsimg.com/754ac5460a5e1531953c79dd1c4863b7?Acc...
- ganzuul 7y agoI thought plasma was a near-perfect conductor... Is that wrong? You don't need high temperature for plasma; just low pressure. There is a big difference between glow discharge and arc discharge.
- davidklemke 7y agoOne of my university lecturers, John Rayner, worked on developing these back in the day. Managed to track down a paper he published on it which is quite interesting: https://ieeexplore.ieee.org/document/1291644 https://ieeexplore.ieee.org/document/1291644
- Razengan 7y agoTechnologies like this suddenly make a lot of science fiction seem outdated. :)
- mjfl 7y agoYour microwave has a plasma antenna in it - it makes microwaves. It’s called a magnetron
- willis936 7y agoOr a gyrotron if you eat really big hot pockets.
- danepowell 7y agoDoes anyone know how stealth fighter aircraft are able to incorporate radar hardware that doesn't act like a giant retro reflector? Putting a radar array on the front of a stealth fighter just seems like painting a giant bullseye on it, even if it's not emitting. I wonder if something like this could already be in use, since it becomes invisible to radar as soon as the plasma generator is turned off?
- hgoel 7y agoI'm not exactly versed in the subject, but going off of a recent class on wireless transmissions, perhaps they instead use lots of small transmitters/receivers along the hull and rely on post processing to piece that together.
- patosai 7y agoI've never worked on stealth aircraft, but energy has to travel from the transmitter, through the aircraft's radar cover, off the array itself, then get back through the cover and back to the receiver. There are probably ways to filter for specific RF frequencies on the cover so only those in specific bands can get through, then the array itself might absorb some portion of the energy that gets through. The array also might be at an angle so waves are reflected in a different direction, or there might be radar absorbing material placed in specific spots that helps minimize reflections. I think the arrangement of elements in the phased array itself could also lead to reduced RCS at certain angles. Again these are just educated guesses, I would imagine the details are classified.
- syphilis2 7y agohttps://aviation.stackexchange.com/questions/25368/how-are-antennas-integrated-into-stealth-aircraft https://aviation.stackexchange.com/questions/25368/how-are-a...
- DoctorOetker 7y agopeople interested in this may also be interested in GDD Gas Discharge Detectors, they can also be used for mixing / heterodyning
- bcaa7f3a8bbc 7y agoWow, a gas discharge mixer! I couldn't believe it exists...
- DoctorOetker 7y agoI think I have seen projects using miniature neon indicator lamps tubes as GDD's / mixers I have often toyed with the idea of making oscilloscopes, and spectrum analyzers with them, but that would take a long time to explain... Also, I miswrote it's Glow Discharge Detector Another idea is repurpousing plasma display panels as a grid of GDD detectors, as an imaging array. For an example circuit using a neon indicator lamp see figure 1 of the 2010 article: http://www.academia.edu/download/44461415/Heterodyne_Detection_by_Miniature_Neon_I20160405-1310-1do4wyg.pdf http://www.academia.edu/download/44461415/Heterodyne_Detecti... This 2016 article measures the light emitted from the neon indicator lamp instead (with FMCW scheme to detect distance as well) https://www.osapublishing.org/viewmedia.cfm?uri=prj-4-6-306&seq=0 https://www.osapublishing.org/viewmedia.cfm?uri=prj-4-6-306&... This setup improves response time (bandwidth) of the output signal.
- peter_d_sherman 7y agoFascinating! Did not know you could make an antenna out of a plasma; this is fascinating; thank you for expanding what I thought was possible!