From the third link (photo) above, there's RF test points next to what I assume to be the 2.4GHz aerial on the left and the 5GHz aerial on the right (assuming the larger to be the 2.4GHz).
I got an IPEX-K to RP-SMA pigtail not realising that the test points aren't IPEX but something else:
It's a bit hard to know which connector fits perfectly on those probe sockets. In theory these are MS156 connectors.
Some time ago I bought one MS156 pigtail (for a different board), and it almost worked, but it definitely got loose. It's possible that the seller sent me a defective one.
Those are designed for factory testing in a test fixture that presses a pin into the connector while holding the whole board in place. There isn't an official way to connect a cable to them permanently.
Also it looks like the side antenna is connected only to the 2.4 GHz radio, the one nearer the corner of the board is dual band, and the one at top center is 5 GHz only.
Any chance an MS156 plus a rubber-band might work... :o)
@mk24 - this board has a DECT radio on it - I figured the left-most was the DECT, middle was 2.4GHz and the right-most 5GHz - does that sound possible?
As mentioned by mk24, these connectors aren't meant to be locking, accordingly there is no way to achieve a stable permanent connection. On top of that the internal antennas remain in the signal path, so the result of adding additional antennas in parallel would be rather bad.
