I've built several similar devices (but for tetherball)

One has been in service since 1987

Use galv pipe

Embed a pipe stub inot the concrete and use a coupling to attach the
pole

drill through cross holes in the pipe to accept small (1/4 or 3/8)
rebar

The bond between black pipe or galv to concrete is minimal, it's the
bumps that do the job.


The black pipe is more trouble than it's worth; rust / painting
cheers
Bob