Here’s a closeup of the Z-Wave daughterboard:
You cut, or desolder, the joints in the red and yellow circle. Desoldering can be done from the top, the daughterboard doesn’t have to be removed or anything.
The new antenna will be connected through a thin coax cable (the following photo is from a regular coax cable, but the same structure applies to thin cables too):
You solder the core wire, “D” in the photo, to the pad in the yellow circle. The shielding (“B”) can be soldered to the point in the red circle, but it’s not required (do make sure that if you don’t solder it, it’s properly protected against making any contact with any part of the PCB).
