I used a 5" diameter schedule 40 Galvanized post with caps available 4 plus feet in the hole, 12" scrap welded to post in a few places at 90°, 36" diameter hole and as much concrete as needed.
1 1/2" tubing horizontal, 2" vertical, redwood 2 x 4 's attached to the 1 1/2" tubing with galvanized...