On Sunday, May 14, 2017 at 6:58:48 PM UTC-4, Andy wrote:
I have an antenna mounted on a pole that is attached to a block of wood.

Sometimes I have to change the antenna position.

I would like something to put under the wood that would allow the wood to rotate freely.

All I could think of was a wheel bearing.

Any other ideas ?

"Rotate freely", like whenever the wind blows?

You really haven't supplied much information. How big is the antenna? How
tall is the pole? How big is the block of wood? Where is this contraption
located - on the ground, on the roof, on a wall?

Seriously, could you be any less detailed?