A Plague of Angels (or, Rorschach in your living room!) (Peter Watts)
Yes, the technology will improve over time; yes, efficiency will increase. But we're still talking about an omnidirectional broadcast here; even if the bulk of the signal strength passes in one direction, there's still going to be at least some wasted energy going out along the whole 360.
More to the point though, is Smith's confident assertions that "the human body is not affected by magnetic fields". Maybe he's talking about a different model of human body. Maybe the model he's talking about comes with a Faraday cage built into the skull, and is not susceptible to the induction of religious rapture, selective blindness, or the impaired speech and memory effects that transcranial magnetic stimulation can provoke in our obsolete ol' baseline brains.