Hello @Shrfid
Hope you are doing well.
AN1715 is a very old resource and may no longer be available.
I will recommend you referring to UCODE G2i PCB Antenna Reference Designs. This App Note describes three antenna reference designs for the UCODE G2i IC for implementation on a Printed Circuit Board.
Also, for UHF Antenna Design, you can consult UHF RFID Label Antenna Design.
Regards,
Eduardo.