So I should drive this post into, say, the loose dirt I find in the San Fernando Valley, then fill THE POST with concrete? If you meant for a larger hole to surround the post, about how large should it be to "ain't going nowhere"?

It's been amusing to see dishes on front yard posts just north of large trees, or attached to chain link fences back in the days when we only had to aim at the 101 satellite. My favorite was the one I put on the side of a chimney in new construction where the GC told me which direction was north from the plans, and it was wrong. I had a satellite mount built onto the side of the chimney before water seal, and I had to build an extension to move the dish about 20" out from the chimney to peek around the corner in the correct direction.