Researchers Develop 2D Spray On Antennas

Discussion in '[H]ard|OCP Front Page News' started by AlphaAtlas, Sep 25, 2018.

  1. AlphaAtlas

    AlphaAtlas [H]ard|Gawd Staff Member

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    Researchers from Drexel University developed a spray that can be used to paint a "two dimensional" antennas on a surface. Traditional copper antennae typically found in small electronic devices are relatively large and thick, as they're limited by the "skin depth" effect. Curiously, the 100 nanometer titanium carbide layer researchers sprayed onto the surface seems to defy the predicted minimum required thickness, and the researchers don't really know why. The researchers claim that mass producing the antennas would be simple and cheap, but are looking into using different base materials in solvents other than water so that the antennas won't wash off surfaces. One researcher says "with respect to transparent antennas, we believe there are applications we cannot imagine."

    Check out a video of the tech here.

    The "spray-on" description is exactly what it sounds like. By dissolving MXenes in water, researchers produce a kind of water-based ink. Then, "we can just use a simple spray gun from Home Depot, and just spray the shape we want," Sarycheva says.
     
    Last edited: Sep 25, 2018
  2. The model they are using for wave propagation assumes a perfectly flat surface. Waves can propagate in more than one direction and antennas can be optimized for the propagation path. Truth is layered molecules are anything but flat and because of the transition from layer to uneven layer, the path taken is longer by as much as 20% or more in a lattice formation.

    Although sensor design is in my wheel house, rf & antenna design has always been a black art though. Outside my direct expertise.
     
  3. pcgeekesq

    pcgeekesq [H]ard|Gawd

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    They're putting down a layer of titanium carbines? What caliber does a 100nm carbine fire, though? :confused:
    Oh, that's meant to be "carbide," isn't it? :)

    I like that the antennas wash off. Given that you can use an antenna as a passive sensor, it offers all kinds of possibilities for covert ease-dropping. I bet the spooks already have thought of that.
     
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  4. tikiman2012

    tikiman2012 [H]ard|Gawd

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    I think that they're going to have a hard time finding something to use other than water. I wonder how bad other base materials will isolate the titanium carbide particles.
     
  5. WBurchnall

    WBurchnall 2[H]4U

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    Whose to say the spooks didn't event this years ago in a lab and aren't already employing it? Perhaps, they just don't publicly release that info to stay ahead of their competition.
     
  6. d8lock

    d8lock Gawd

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    This might make roof antennas easier to put up.
     
  7. DukenukemX

    DukenukemX 2[H]4U

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    Am I wrong to say that an antenna is just a lawyer of metal that's carved into a shape for best reception? If you've taken apart your phone you'd see that it's just a thin layer of metal. Couldn't I just use something like aluminum foil and cut it to shape? Would seem cheaper than spray on titanium carbine.
     
  8. Photo etching an antenna on a circuit board works just as well. But this technique has possibilities for non-flat surfaces that circuit boards do not.

    And using aluminum foil depends on the frequency and application. You can put aluminum foil on the end of rabbit ears and improve reception. Most antennas can have a minimum length equal to half wavelength. Then you can fold them to increase their "virtual" length. Then there are designs for good back rejection (like UHF bowtie antennas) like I said, it's a black art with many permutations and def not my specialty. Then there's multi direction pickup. But for every antenna your input power for Antenna x is cut by 3dB as it flows out the adjoining antenna.

    Russia and the CIA had a completely passive antenna that doesn't work at all until it was energized by a microwave source. That way they could turn it on and off at whim making it near impossible to find. They found one hidden in a gift "seal" print from Russia. It was planted inside an american embassy after some time.

    There's even better ways to hide them now with low power application. They would be virtually impossible to detect.
     
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  9. kju1

    kju1 2[H]4U

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    Wait when you say passive antenna do you mean one w/out a built in amplification stage?
     
  10. Yep. The powered it remotely using microwaves. It's in the US spy museum. A fun little place to visit.

    We have devices which can be powered entirely with latent rf energy from wifi.

    Spy agencies have also been putting laser interfrometer at windows. Windows act like a speaker and vibrate when there is noise. The laser interfrometer can pick up these small movements like needles on a record and transcribe speech from inside the room.
     
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  11. sfsuphysics

    sfsuphysics I don't get it

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    So it's "2d" because it's thin? Does that mean old school car antenna are "1d" because only one direction has any significant size?
     
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  12. kju1

    kju1 2[H]4U

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    So to be fair youre talking about more than an antenna there. There is a microphone involved etc. A passive antenna is just a hunk of metal. So if I take a regular TV antenna and grab a signal off it with no amplifier I have a passive antenna.
     
  13. That's the idea. But antenna is passive in the fact it does have an amplifier as it's powered from the external microwaves.
     
  14. That's true. There is conductive paint used as antennas on cars. Forgot about that.
     
  15. pcgeekesq

    pcgeekesq [H]ard|Gawd

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    There doesn't have to be an microphone associated with the antenna: an antenna printed on a substrate that vibrates or flexes in response to acoustic energy (such as most window panes) can itself act as the microphone by any of a number of techniques.

    I am reminded of old tube-based amplifiers. It was not unknown for someone to be playing a recording on a PA system and have the tubes pick up a conversation in the room and send that conversation out over the speaker system as well. Per Wikipedia, Microphonics: "The charged elements in the vacuum tubes can mechanically vibrate, changing the distance between the elements, producing charge flows in and out of the tube in a manner identical to a capacitor microphone."
     
  16. bluesynk

    bluesynk Limp Gawd

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    I used to make (manufacture) microwave antennas. The engineer admitted he had no clue how to design an antenna. The whole industry seems to work on a "this is what seems to work" basis. anything other than the normal "multiple of the desired wavelength" is trial and error.
    any attempts ive made to learn much more have failed. Black art indead. Someone knows and is not sharing.
     
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