In practice, there is always a location on the patch where impedance at F resonance will be purely real and 50 Ohms.
The wider is the crossection of the patch the closer this point is to the edge of the patch.
For suspended plate-type patch, to find exactly where is this point I cut narrow slot in the patch, install connector from the bottom of Ground plane and slide the patch along the connector to find this sweet spot. fast and gives accurate results. Just do not forget to fill the slot with solder.