I would recommend to use for your mobile design, instead of a Patch antenna, a PIFA (Planar Inverted F Antenna). Actually the last one is the most used approach in mobile phones.
PIFA have multiple advantages over Patch antenna in a mobile design:
Slightly wider bandwidth, availability for multi-band design, higher gain in both vertical and horizontal polarization, less sensitivity to human body interaction (due to large current flows on the under-surface of the planar element and the ground plane).
The distance between the active element and the PCB ground for a PIFA antenna used in a handset, is not standard, and it is somewhere between 3 to 6mm (or maybe more if the handset design allows for higher thickness).