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nRF52840 matching network for pin 31(ANT), matching circuit needed for regulatory requirements, EMC

bjornshnrf

Hi,

We are close to going into a certification process but before we start we need to be sure we are not missing out on your recommendations with regards to EMC performance.


Is the radio matcing network needed for other purposes than matching towards 50ohm? Is it needed for regulatory approval? 


Can you share the impedance at pin 31 (ant port) of the nRF52840?



Thanks,

Regards

Bjørn

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  • 0

    Hi, 

    Thank you for the answer and clarifications.

    I did a simple test with a simple circuit and VNA. I made two circuits - both equal to your two alternative matching circuits. I will only give feedback on the 3 component pi network.

    When assuming 50ohm looking back into the nRF52840 through the matching network (as you listed in the post) - we can do the measurement from the other side of the matching network to get an idea about the optimum load for the radio and ANT port. This impedance is  the optimum load impedance. 

    I then simulated this by making a source with this impedance in serie with the matching circuit and observed optimum transfer of power (low S11) through the matching circuit to the 50ohm matched antenna. 

    Anyways, good feedback on the need for this network for regulatory certification and that the ANT impedance is not 50 ohm.

    Thanks

    Regards

Reply
  • 0

    Hi, 

    Thank you for the answer and clarifications.

    I did a simple test with a simple circuit and VNA. I made two circuits - both equal to your two alternative matching circuits. I will only give feedback on the 3 component pi network.

    When assuming 50ohm looking back into the nRF52840 through the matching network (as you listed in the post) - we can do the measurement from the other side of the matching network to get an idea about the optimum load for the radio and ANT port. This impedance is  the optimum load impedance. 

    I then simulated this by making a source with this impedance in serie with the matching circuit and observed optimum transfer of power (low S11) through the matching circuit to the 50ohm matched antenna. 

    Anyways, good feedback on the need for this network for regulatory certification and that the ANT impedance is not 50 ohm.

    Thanks

    Regards

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