feed point on GPS antenna

Can any one provide calculations for feed point on ceramic substrate used in GPS antennas?

The position of the feedpoint is important as it should present a 50 Ohm impedance.

May it helps
http://www.zendar.it/patch_gps/estra...ticolo_GPS.htm

regards

The majority of the PatchAntennas use a probe feed coming from the bottom side. If this is the point you're trying to find to get a good match, this article should help.