Tracker Accuracy

I have been using the Mission Planner and Ardupilot Trackers for many years, but only with relatively low gain antenna. Now I will be using a high gain antenna (Ultra Wide Band Parabolic Grid 600Mhz - 6.5Ghz — TechnicalAntennas.com) so I am particularly concerned with the accuracy of the Tracker. I would much appreciate if anyone has done error analysis of the Tracker or can provide guidance on how to minimize the error.