T
Hello,
I begin with this RFID UHF reader (U107), and i encountered the same issue to solve, i.e. to optimize the read distance when "Europe work location" is selected.
The patch antenna within the U107 seems fitted to 900MHz band, and as this antenna is very small therefore the bandwith is really narrow. The read performance at 868MHz are then degraded.
The solution I found is to modify the patch antenna like this: you have to remove the box to access the top of the patch antenna, and you have to remove the white adhesive protective sheet and stick in place a square of aluminiun adhesive tape above/againts the roof of the integrated patch antenna.
The size of about 30mm by 30mm seems close to the best ... but you can try other sizes and see. You can also try cropping the opposite angle along the diagonal passing between the two feed points (not a lot !).
Best regards,
Thierry