Which M11 2.4 GHz do you have? I can speak for my DSSS only, but I assume it's the same with any 2.4 GHz.
The antenna wire is coaxial cable and it's not soldered to the pcb but plugged in, so you can replace it fairly easy. You can take a look at oople where they show an open tx module with the antenna plug connected.
I'm not 100% sure but I think, the receiver antenna ist plugged in, too?


Regards,
T