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minicam antenna

Discussion in 'General Electronics Discussion' started by Nevadawill, Mar 17, 2012.

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  1. Nevadawill

    Nevadawill

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    Mar 17, 2012
    I have a 2.4 gHz wireless minicam with a built in antenna. The antenna is just a short wire sticking out the back of the unit. I want to use it in a metal building with the receiver a few hundred feet away, but the transmitted signal doesn't penetrate the metal siding and roof. If I stick the wire antenna through a hole in the metal, it works. My problem is I don't want the camera placement by that hole. Can I get away with soldering onto the wire antenna some 50 ohm coax and extending that through the metal skin, and then just stripping the end of the coax the same length as the attached wire antenna? Any help is appreciated.
     
  2. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

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    Does the antenna unscrew? If it does then it most likely uses a standard connector and you can probably get a "wifi" antenna and cable that will screw in.

    At 2.4GHz most coax has very high losses. You need special coax. The cheapest source is probably the same as above, a wifi antenna with cable. In this case, cut off the connector and solder the inner connector and the braid to the appropriate locations.
     
  3. Nevadawill

    Nevadawill

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    Mar 17, 2012
    Thanks Steve.
    No, the antenna doesn't unscrew. That would be too easy. It is just an light gauge single insulated wire coming out the back of the. plastic housing..So I'll solder the inner wire of the suggested wifi antenna cable to the existing single wire where it emerges from the camera back and just leave the shielding alone and out of the way, Easy enough. Thanks again, Nevada
     
  4. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

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    No, solder the shield to some obvious ground point. There should be one nearby.
     
  5. Nevadawill

    Nevadawill

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    Mar 17, 2012
    Got it. I'll bond the shielding to the metal building. Thanks again Steve, Nevada.
     
  6. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

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    No, on the circuit board. Somewhere near where the antenna connects there should be a ground for the braid to connect to.
     
  7. Nevadawill

    Nevadawill

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    Mar 17, 2012
    OK. So I have to break into this penny sized camera, unsolder the antenna wire, replace it with the center wire on the coax, find a ground on the pc board and connect the coax braid to it. This is getting complicated. This minicam,in addition to the attached single wire antenna, also has a pigtail with a female phone jack tor a 9v battery or an 8v plug in transformer. Would the negative connection on that pigtail go to ground on the pc board? I don't have any schematic for this thing, but tapping into that pigtail for a ground would be way easier than trying to get the relatively large coax into that very small camera package...

    Thanks,Nevada:
     
  8. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

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    Given that you can probably get away with a lot of losses, you may be able to do that.

    However, realise that at 2.4GHz, even a short length of wire can have a huge impedance. If you can keep the wires in the order of 3mm in length you'll be fine... (that's not going to happen, right?)

    Try it. If it doesn't work, you may have to take a more invasive step.
     
  9. Nevadawill

    Nevadawill

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    Mar 17, 2012
    All right. So if I understand correctly, if I can solder the center coax wire to the existing antenna wire where it exits the housing. and solder the coax braid to the negative power lead where it enters the housing, I'm doing about the best I can short of opening the housing up and messing with. the inside pc board. I'll give it a shot.
    Thanks Steve, Nevada
     
  10. roughshawd

    roughshawd

    21
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    Jul 13, 2020
    Antennas are real picky about their antenna.... just take a Dime... US Dollars, and glue it to the case near the wire, it should give you at least another 15 feet.
     
  11. davenn

    davenn Moderator

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    this thread is 8 years old
    please check age of last posts before responding :)


    thread closed
     
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