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Antenna

Discussion in 'Electronic Design' started by [email protected], Feb 13, 2013.

  1. Guest

    Hi,

    I am trying to change the antenna on the USB bluetooth dongle just showed in the following youtoube video



    This "bluetooth dongle" allows my Data Acqusition Software to talk to my " bluetooth Device". Right now, both devices stop talking to each other when I walk carrying the "bluetooth device" more than 25 to 30 feet away from my laptop.

    I am using the following bluetooth Dongle
    http://www.amazon.com/Wireless-2-4G...=1360784003&sr=8-23&keywords=bluetooth+dongle

    The thing is that the guy did not mention the what kind of Antenna will work with this 50 ohm Jack. I am trying to increase the range of the bluetooth dongle. If this is true then what type and dimension of the antenna should I use.

    I used the following antenna with the Jack but still I loose bluetooth connection, if I walk away form the laptop more than 25 to 30 feet.

    http://www.digikey.com/product-search/en/rf-if-and-rfid/rf-antennas/3540022?k=730-1000-nd.

    Any suggestions


    Thanks

    John
     
  2. mike

    mike Guest

    What range do you need? Are you really "walking around"
    or can you use a fixed location with directional antennas?

    When you can, put the bigger antenna at the fixed location, not
    the mobile one. Both is better.

    Most youtube videos are put up by people who haven't a clue.

    It's possible that you lose more in impedance mismatch than you
    gain from the external antenna...assuming you didn't short the
    connection or leave the shield disconnected.

    For fixed paths, the usual thing is to use a usb extension
    cord and put the dongle at the focus of a parabola or
    inside a cantenna. Google "war driving" for tips.
    Sometimes merely relocating the dongle on the extension
    cable can get you a few more feet.
     
  3. You need an antenna for 2.4GHZ-2.48GHZ. Check the wiki.

    Cheers
     
  4. Owen Roberts

    Owen Roberts Guest

    Adding a new antenna may not help you much. Commercial antennas are
    designed for a 50 ohm impedance. The impedance matching on a
    Bluetooth board rarely matches the 50 ohm spec. In fact its often
    closer to 20 ohms. This is deliberate to limit range by using a
    barely radiating antenna to meet the FCC and International standards
    for a intentional radiator. It is also what allows Bluetooth users to
    share spectrum space the way they do.

    Steve
     
  5. Glenn

    Glenn Guest

    Hi John

    You need a hill (maintain line-of-sight) and these antennas. Go for it -
    break the record ;-)

    July 30th, 2004, New World Record for Bluetooth Link!:
    http://www.wifi-toys.com/wi-fi.php?a=articles&id=21
    Quote: "...
    The test: Connect to a low-power Bluetooth cellphone from a distance of
    1 kilometer

    The result: Success!
    ...."

    /Glenn
     
  6. This seems unlikely. Have a look at the application notes for any of
    the widely used BT chips. You will find plenty of detail on
    optimising the matching to a 50 Ohm antenna.

    John
     
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