In the bottom of the pool, a submersed pump gets
the water moving around in a circle... the velocity
of the water determines the shape of the "dish" formed
by the water (which is parabolic).
Above the pool, dead-center in the focus is of course
the feedhorn and LNA.
The ping-pong balls ought to be small enough not to
cause much phase error at the focus at 1420 MHz.
I suppose there'd be problems with freezing during
perhaps some antifreeze would help out.
Another problem is making sure that the balls maintain
contact with one another.
If they neighbors ask, tell'em it's abstract art :)
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