nRF52840 Dongle matching network for ext. Antenna

RE: nRF52840 Dongle matching network for ext. Antenna

Quas7 — Sat, 09 Aug 2025 16:42:22 GMT

Just wanted to share an U.FL mod that worked for me very well to attach directional antennas. I used transparent UV soldermask after scratching off the solder pads for the connector. A bit hard to see in the pictures.

RE: nRF52840 Dongle matching network for ext. Antenna

mugsimar — Wed, 20 Jan 2021 13:14:29 GMT

Hi Aleksej!,

I'm trying to do the same. How did you connect the SMA ground pad to board ground?

Thanks,

Miguel

RE: nRF52840 Dongle matching network for ext. Antenna

Kaja — Fri, 13 Mar 2020 15:37:29 GMT

Your welcome!

And we are always happy to do HW reviews of your customs designs.

Best regards,
Kaja

RE: nRF52840 Dongle matching network for ext. Antenna

Aleksej — Thu, 12 Mar 2020 17:54:41 GMT

Hi Kaja,

Many thanks for the fast response and clarifying, which components are for which matching.

RE: nRF52840 Dongle matching network for ext. Antenna

Kaja — Thu, 12 Mar 2020 15:19:53 GMT

Hi,

if you want to change out the pcb antenna with an external antenna, you still need to have C3, L1 and C4 on the board because this is the matching components for the radio. Changing the impedance of the radio to 50 Ohm.

C25, R1 and C26 is matching components for the antenna, if you change out the on board antenna with the external antenna, and you connect the SMA connector to the 50 Ohm transmission line, you should be okay without matching components as long as the SMA connector and the antenna has a 50 Ohm impedance.

Best regards,

Kaja