JAWUG

This is a list of optimal Ranges for Different gain antennas. This is subject to perfect LOS with enough ground clearance to ensure a clear FreshnelZone+ and low noise.

24dBi

1mbit 16km
2mbit 13km
11mbit 10km
higher 8km

14dBi

1mbit 8km
2mbit 6km
11mbit 4km
higher 3km

12dBi

1mbit 5km
2mbit 4km
11mbit 3km
higher 1km

These figures were adjusted a bit, to account for typical noise levels that you will encounter in and around Johannesburg.