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Could somebody help me identify this odd device?

  1. Sep 4, 2011 #1
    Now, i'm not very well versed in the engineering side of telecommunications and what-not, so i was wondering if somebody could tell me what this was, i've exhausted all other options. It was glued to a window when my uncle moved into his apartment. The black box is the size of a matchbox roughly. I have no idea what this could be apart from possibly an rfid or something.

    Thanks in advance.

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    33cma94.jpg
     
  2. jcsd
  3. Sep 4, 2011 #2
    Just wanted to add, theres no spot for a cable or anything to connect to it, and no circuitry except for the odd copper shape in the middle.
     
  4. Sep 4, 2011 #3
    Are the "antennas" even connected to the copper, or are they just sitting on the silkscreen? That's a piss-poor soldering job there, anyhow.

    Barring some obscure use that I don't know about, I'd hazard a wild guess that it's some sort of "EMF cancellation" piece of garbage that you'd sell to people who want something fancier and less obviously loony than a tin foil hat, if you catch my drift.

    BTW, please put images that big in spoiler tags or reduce them so they don't screw up the layout.
     
  5. Sep 5, 2011 #4

    sophiecentaur

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    It could just be garbage or, on the other hand, it could be a tuned reflector - a sort of passive bug that would give a 'good' reflection at its resonant frequency. Those inductors in series with the dipole elements and the capacity plates (?) could be tuning elements. It would depend on the quality of the build.
    I wouldn't say the soldering was poor- it appears to me that the inductors are soldered to vertical pins which are already in the board. What's on the other side of the board (is it double sided or are those shapes we can see on the underside) and up inside the lid of the box?
    Was it given to the owner by an Alien?
     
  6. Sep 5, 2011 #5
    Thanks for the detailed replies guys. On the other side of the board there is just a rectangle in the middle, no copper portions. There is nothing inside the black housing, i just pulled the board out of in for that picture but couldn't fully get it out since the antenna were glued to the plastic, thats why it looks kind of weird in that picture.

    What would the tuning bug be for?
     
  7. Sep 5, 2011 #6

    sophiecentaur

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    If this is a 'real' piece of kit, it could either be to act as a reflector at a certain frequency - or some sort of passive way to increase the local level of some signal - say Wifi. Either way I can't see it being very effective - except as a source of income for the manufacturer and seller.

    From the component sizes,it would probably work at around 1GHz.
     
  8. Sep 5, 2011 #7
    One thing I overlooked, it does say "CH-01" on the board but nothing else.
     
  9. Sep 8, 2011 #8
    With the copper spaced that far apart, wouldn't the capacitance value be super, super small?

    I don't see any vertical pins in that solder blob, it looks like it's just "hot glued" to the silkscreen with a blob.
     
  10. Sep 8, 2011 #9

    sophiecentaur

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    You could well be right about the soldering but it looks too neat to me and just what would those plates be made of if not copper beneath some green lacquer. Perhaps they're soldered to two circular holes in the lacquer . The capacity between those plates would only be a couple of pF. which would resonate with a few nanohenries (?) at several hundred MHz.

    We'd need to have hands-on to be sure either way.
    One thing's for sure and that's that is the device probably cost a lot more than it's worth.
     
  11. Sep 8, 2011 #10

    berkeman

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    Perhaps it was meant to couple signals from a device inside the window to the antenna outside the window. The coupler portion inside the window would capacitively drive the two plates differentially....
     
  12. Sep 8, 2011 #11

    dlgoff

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    Last edited by a moderator: Apr 26, 2017
  13. Sep 8, 2011 #12

    sophiecentaur

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    You are not just a pretty face, berkeman. That's the most constructive idea so far. Respect.
    But why not put it on the same side of the glass, which is transparent to rf, surely?
     
  14. Sep 8, 2011 #13

    berkeman

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    Awww :blushing:

    But yeah, now I'm wondering how it works. I'd assumed that there was a coax feed to a differential balun that was glued to the inside of the glass, but the info on the package and at www.Callet.com calls it a "Passive Repeater". So somehow it resonates with the cell in the house/car, and helps to get the pattern better outside the house/car?
     
  15. Sep 8, 2011 #14

    dlgoff

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    $$$$$$$ :biggrin:
     
  16. Sep 8, 2011 #15

    dlgoff

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    Actually, it's http://www.cellet.com/catalog/product.php?productid=12024&cat=320&page=1" [Broken].

    Back in the day I had one that was made with a coax input but this one has an antenna input.

    Edit: Found this and wonder if it should be in the Product Claims forum:

    http://cellphone.rlstuff.net/cellet-car-mount-passive-antenna-repeater-acar3a/" [Broken]
     
    Last edited by a moderator: May 5, 2017
  17. Sep 8, 2011 #16

    berkeman

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    Oh, I get it now. The two pieces go on opposite sides of the glass. Duh.

    Yeah, I can see how it might help for a car, but even there you would lose a lot of power with the passive nature...
     
  18. Sep 9, 2011 #17
    Wow, you guys solved the mystery. Thanks so much. Who would've thought that it would turn out to be something so obvious. Come to think of it, when i asked my neighbour before posting here, this cell phone antenna thing was the first thing he suggested but i blew off the idea :P
     
  19. Sep 9, 2011 #18
    Now that we know exactly what is is, thanks to dlgoff's link, the next question is: Does it even do anything?

    Since it's completely passive, it can't actually give any power gain. Resonance can, at best, increase the efficiency to close to 100%, but it can't magically pull free power out of its aether.

    The most I could see this being useful for is spreading out the signal it's receiving, possibly to reduce shadow zones or something I do't suspect that that is a significant problem for cell phones, at least not one that can be solved by this device.

    Either way, it seems fundamentally impossible for this thing to be a "booster". Does it actually do anything worth $20?
     
  20. Sep 9, 2011 #19

    sophiecentaur

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    It won't be better than holding your phone up to the window but it could sometimes fill in a bad spot inside the room. This could avoid having to stand on a chair or holding the phone up in the air to get a usable signal.
     
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