Create arbitrary fields through simulation, measurement, and calibration.
A wave traveling between two parabolic antennas https://www.youtube.com/watch?v=v0cZjOIfwos You might try receiver-transmitter pairs, where each inverts the signal to build a standing wave. Use the final state inside the volume (arbitrary and time dependent if you want) as the constraint, then solve for the signal modifications needed at each site. I first saw this more
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