I would go with Sched40 steel pipe, found at any hardware or plumbing supply, mounted in high load Quikrete. Quikrete has a how to on their website for you as well.
If you need it 10' off the ground maybe a roof or chimney mount would work? If you still need it mounted in the ground, I would dothe Sch40 in Quikrete.
its not for me its so that I can pre buy it for future customers that live in an apartment whose only option is to have their dish mounted on a tri-pod in their balcony.