what load impedance is preferred seen into the matching network?

[bob]

Hi,

For 52820-QDAA, what load impedance is preferred seen into the matching network?   I mean the total load impedance of C3, L1, C4, L2, RF trace and antenna.

Since our product is small and layout can not be exactly same as recommended, we have to change C1, L1, C4, L2 values if needed, then measure impedance at ANT PIN to make sure to be preferred by 52820-QDAA. So we need to know the load impedance seen into the matching network

Here is another post which is talking about NRF52833-QIAA , a similar question.  Can anybody help me out? Thanks!

https://devzone.nordicsemi.com/f/nordic-q-a/84014/what-is-the-output-impedance-of-the-ant1-antenna-pin-on-the-nrf52833-qiaa/349797#349797

Best regards,

Bob

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[ketiljo]

You need to break the connection between L2 and C16 to get a correct reading. And you need to set the radio in TX mode, there's a great difference there. 

Ans make sure the cable's outer conductor is soldered to the ground plane. Have you calibrated the cable?

[bob]

Hi ketiljo, when I am trying to get 35 -j46 ohm seen into the matching network from the ANT pin, I got a good point, but what is the frequency when we say 35 -j46 ohm?  Is it 2400 Mhz, or 2440 Mhz? If we are talking about different frequencies, then there must be a deviation.

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[ketiljo]

Middle of the band, 2440 MHz.

[bob]

Thank you ketiljo, I can get good antenna performance now.

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