I read about magnetic induction communication on Lockheed Martin's wireless mining communication system
In this interview Warren Gross said:
We generate a signal and send it through a loop that's wrapped around a pillar in the mine. When you send the signal through a loop of wires it creates a magnetic moment or a magnetic field. That magnetic field essentially creates a bubble of magnetic energy which rises to the surface.
I thought magnetic field will be around the object(coil or magnet) and doesn't shift or move away. Does magnetic field or magnetic bubble rise to the surface like air bubble in some condition?