RAK811 RF_OUT / antenna



  • Hi :-)
    I'd like to layout a PCB for RAK811 but I'm confused by the path from pin 33 RF_OUT to the antenna.

    WisNode-LoRa Schematic_20161216.pdf shows 10pF for L1 and "NC" for C13 and C14. The picture of the board shows clearly components mounted at the positions C13 and C14.
    Not so clear: is there a component at position L1?

    The PCB picture rather fits the description in the datasheet V1.2.
    This datasheet shows in section 5 no value for L1 but 100nF for C1 and C2.
    (my understanding of RF technology is clearly limited - to connect 100nF like this does not make sense to me. Is this a copy/paste bug and did someone forget to put in real values?)

    what would you advise me to do?

    thanks a lot for your support
    Peter



  • Hello

    The RF match circuit , normally, LLC, LCC or LC is OK, the truly value should do a antenna matching test with your antenna . Gernally , we only paste the 10 pF for L1.

    Thanks



  • @peterz Hi,The design layout in WisNode-Lora reserve the area for LC filter circuit. The purpose is provide
    the flexibility for the developer to adjust the components value to reach best RF performance
    with external antenna. The different value should depends on the Casing, Design and position
    etc. Also, we have silk print with L1(see picture 1.0). The default components we used as CAP in
    this area only for basic function. Therefore,is not required soldering C13, C14;Reason:
    And on our WisNode-Lora Board, there is no strong signal source near the antenna line. So
    no need to add LC filter; and in the position of L1, we welded a capacitor. You need to decide on
    what to do according to the actual situation.


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