Half a croissant, on a plate, with a sign in front of it saying '50c'
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Flame antenna

Big and quick.
  [vote for,

Sometimes it would be good to have a very tall antenna, but impractical to carry one of the requisite size. Persons in remote areas trying to receive signals might benefit from a tall antenna - likewise lunar or other explorers. I propose that a tall flame jet could serve as an antenna. Flame is conductive by virtue of the ionized combustion products. Compressed gases can jet very tall flames. Such an antenna could be generated with a compressor and the fuel for a vehicle.

One could MacGyver up a cellphone augmenter using a campfire (or crashed vehicle) producing tall flames. Finally, for deep space communications, one could cause the flame jet from a rocket exhaust to serve as a long antenna. Chemical combustion rocket engines would make flame, but nuclear or even ion drives should serve if dense enough to conduct.

This would make a very slick science project. One could tune a little radio to a distant station. One could have a tall antenna handy and persons looking at the display could connect the tall antenna and hear how reception improves. One could then connect a tall flame jet (from a propane tank) and hear how the flame can function as an antenna as well. I suspect a neon sign could be an antenna if plugged in, but not if cold - again this would be a visually impressive component of a science fair project.

bungston, Apr 06 2007

Pretty relevant-ish http://flux.aps.org...8/abs/S4000009.html
Someone baked the caveman out of your antenna [GutPunchLullabies, Apr 06 2007]

Plasma Speakers http://en.wikipedia...wiki/Plasma_speaker
Flame plasma conducts well enough to form an electrodynamic loudspeaker [csea, Apr 07 2007]

Plasma Antenna http://www.laborato...ticl/rad/ar060e.htm
Russian paper with nice explanations and photos /diagrams [csea, Apr 08 2007]

Ultraviolet laser conducts electricity. WIll it conduct RF energy? https://duckduckgo....+electricity&ia=web
A metal wire, or salt water, and mercury https://simple.wikipedia.org/wiki/Mercury_(element) will carry electric current or send and receive radio waves. An utraviolet light or laser will "... rapidly heat and ionizs surrounding gases to form plasma. The plasma forms an electrically conductive plasma channel https://en.wikipedia.org/wiki/Electrolaser. Create a variable frequency monopole "Laser Antenna." Place a "coherent perfect absorber" https://en.wikipedia.org/wiki/Coherent_perfect_absorber at the end of the beam to absorb the light to create the proper "physical" length of the beam http://www.hamuniverse.com/hamantennalengths.html . The absorber is adjustable, creating an antenna of variable lengths for different frequencies. Fixed position absorbers could be used also to make antennas in various forms https://en.wikipedia.org/wiki/Antenna_(radio) . The laser or light beam would be pointed at the absorber for the needed frequency as well as pointing a directional antenna in the right position, like an antenna rotator https://en.wikipedia.org/wiki/Antenna_rotator. https://en.wikipedia.org/wiki/Coherent_perfect_absorber Possible downside: This laser wireless power (Tesla's dream) transmitter only provides 25% http://www.popularmechanics.com/flight/drones/a7966/how-it-works-laser-beaming-recharges-uav-in-flight-11091133/ of the electrical energy that emits from the source because, "You're plugging a system into the wall, taking that electricity and converting it to light and transmitting that light through open air to a receiver, which converts the light back into electricity. I don't know how this would play when dealing with radio waves as no abnormal conversions would take place that I can envision. Just a thought: A laser emits energy like a gun or rocket engine. Is their a measurable energy or "kick" like that produced when a gun is fired, when a laser is fired? [Sunstone, Feb 17 2017, last modified May 03 2017]


       Shiny! And I love the idea of a cell phone with a ten meter flame spurting out of the top. Better use a headset though.
Galbinus_Caeli, Apr 06 2007

       I have no sence at all whether or not this would work But sounds cool. I am not sure what all wave lengths come from a flame. I get a sence though that if it can pick it up, it puts out that wavelength when excited. Feel free to educate me on antennas. I have never noticed any radio interfearance from flames, like from power lines and engines and such. Whether that would mean nothing, that it would work or that it wouldn't pick up or recieve I don't know.   

       I beleive I have heard that the ionosphere on the dark side bounces short wave and AM? My guess is that excited by the sun light or solar wind it loosed the bouncy property. On that level I know it interacts.
MercuryNotMars, Apr 06 2007

       Is flame really conductive? Because that is pretty cool. If Ionization is the only requirement, perhaps you would consider a powerful laser? Your antenna could be much longer and have, perhaps not less, but different risks to users.
GutPunchLullabies, Apr 06 2007

       I am not sure that a laser passing thru atmosphere would ionize its path adequately to conduct. For example, I cannot imagine completing a circuit using a laser pointer, but apparently a flame can do it.   

       I used to have a very ancient drier. The motor was unshielded. However, it caused interference on the TV upstairs only when the gas flame jet came on. My hypothesis: the flame jet acted as an antenna and transmitted to interference.
bungston, Apr 06 2007

       That plasma antenna linked by [Gut] sounds essentially like the neon tube I describe at the end of the idea. Although I did not use the term "afterglow mode".
bungston, Apr 06 2007

       Alternate hypothesis: The electrical ignition system ran continuously while the gas was on?
GutPunchLullabies, Apr 06 2007

       mmm. that is probably right.
bungston, Apr 06 2007

       I have just done a quick experiment involving a candle, a digital multimeter and a carrot. Conclusions:   

       1) A candle flame is less conductive than a carrot   

       2) The plastic handles on my meter's probes are not heat-resistant.   

       So, I suspect that the conductivity of a flame is not high - but maybe high enough to work as an antenna (I have no idea). But a carrot antenna would be cool too.
MaxwellBuchanan, Apr 06 2007

       With a large enough flame you won't need to use any other form of communication.
nuclear hobo, Apr 07 2007

       Awesome! +   

       Should be possible to make work. Could also work as the speaker (and perhaps even the microphone?) on a cellphone. Not even halfbaked, but a great millibaked idea. [link]   

       I demonstrated a plasma loudspeaker for a highschool science fair in 1972. It didn't work very well.   

       [MaxwellBuchanan] IIRC The conductivity of a flame depends on the applied voltage; you won't see much at the multimeter's applied voltage (9V.) It gets a whole lot better at several hundred volts.
csea, Apr 07 2007

       This would suggest you could actually speak via a burning bush, provided it was wired in advance.
bungston, Apr 07 2007

       Apart from the conductivity, the antenna must be tuned to the wavelength, which means it must have a certain length. Right now, I can't think how that could be done with ionised air, unless there is a 'ground' terminal at the other end.
Ling, Apr 07 2007

       //The conductivity of a flame depends on the applied voltage// Ah - OK. That's weird, but I guess plasmae are weird. But how does this relate to the voltages you'd be using?   

       //you could actually speak via a burning bush// Persumably to ask "who set my bush on fire".
MaxwellBuchanan, Apr 07 2007

       [Ling] Seems it would be fairly easy to vary the height by adjusting the rate of combustion. Quarter wavelengths, I suppose. I'm not sure exactly where the electrodes would need to go. On further thought, if they have to extend the length of the flame, one might as well use the wire as the antenna! Hmm, just did a search for "plasma antenna", and seems that such exist [link].
csea, Apr 08 2007

       "Private Parts, have you been monitoring the emergency channel for any signal from the downed aircraft?"   

       "No sir - sorry sir. I got distracted by that enormous jet of flame on the horizon sir."
MaxwellBuchanan, Apr 08 2007

       + I like it a hot.
xandram, Apr 08 2007

       Farts are flammable. An anal wire could charge them but you'd have to eat gassy foods to have a long conversation. (plus asbestos pants)
JSand, Apr 08 2007

       //asbestos pants*   

       *Pants Pending.   

       I hadn't seen this idea before and am happy to bun it now, although carrying a roll of antenna wire seems slightly more practical.
AusCan531, Feb 17 2017


       " I have just done a quick experiment involving a candle, a digital multimeter and a carrot "
normzone, Feb 17 2017

       Would this actually work? Really clever. Frankly, it's really clever even if it didn't work.
doctorremulac3, Feb 20 2017

       A flame has a very forceful self. I doubt that the subtles of passing EMF would have a say in. The read would have to be extremely subtle.   

       A forceful signal or one that is tuned to manipulate the flame generated (the fuel reaction and therefore atoms involved), might work.   

       On second thoughts, the flame field further out might be the area of investigation.
wjt, Feb 24 2017


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