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direction coupler

Discussion in 'Electronic Design' started by Levente, Jan 22, 2008.

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  1. Levente

    Levente Guest

    Hi all,


    does anyone can point me to a document describing how to design a
    direction coupler? I'd like to measure SWR, power, etc. I'd make a
    direction coupler out of PCB.

    Thanks.
     
  2. no_one

    no_one Guest

    look up directional coupler
     
  3. Levente

    Levente Guest

    Done that. That is why I ask it here.
     
  4. Baron

    Baron Guest

    PCB eh. I'm guessing VHF. Take a 100mm length of veroboard three
    tracks wide. Centre conductor is the through line and the outer ones
    the sense lines. Stick a diode at one end and a 50 Ohm resistor at the
    other end of the sense lines. Measure the voltage produced between the
    diode and resistor. The diodes should be at opposite ends of the
    board. Also half scale is 3:1 swr.

    Now you need to understand some fundamental electronics to design one !
     
  5. Tom Bruhns

    Tom Bruhns Guest

    Download RFSim99. It includes a tool to design directional couplers
    of various sorts including coupled-line type. Look under
    tools>design>coupler. Both microstrip and stripline are included, as
    well as three other sorts. Note: the coupling given for the coupled-
    line type is for a quarter-wave long coupler. A shorter coupler will
    have less coupling but maintains directionality.

    You can also use ATLC to design coupled lines of a more arbitrary
    cross-section, though uniform cross-section along the length of the
    coupler is still assumed.

    You should be able to find on the web some description for coupled-
    line couplers that have flatter coupling versus frequency; it's done
    by adding sections with looser coupling on either end of a more
    tightly coupled section. You should also be able to find on the web a
    description of how the coupling varies with frequency. I've found
    both of those in the past. Google (or similar) is your friend.

    Cheers,
    Tom
     
  6. John Fields

    John Fields Guest

     
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