Adding an External Antenna to an Internal

Yes but it takes quite a bit of manufacturing, soldering, and drilling to do it.  You need to get longer U.FL to U.FL cables (to reach the places you will mount the correct connectors), panel mount microwave connectors that mate with the external antennas you buy, cut off one end of said cable and solder it to the connectors (did I mention the cables are micro sized and coaxial so no shorts would be tolerated), mount the connectors somewhere on the case of the notebook that doesn't interfere with its normal operation, connect the said cables to the 1350 card after removing the internal cables, attach the new externas to the mounted connectors, and you should be good to go.  Not very portable though.