Inductive powering of a freely moving system

To inductively feed a freely moving system in a confined space, two basic approaches are conceivable. One is to provide with three or more differently directed magnetic fields from the outside. The other is to use three or more differently oriented receiving coils. In this text, the achievable efficiency under worst-case conditions is investigated for both options. Some basic working methodologies are handed as a means to identify the worst-case conditions. The wireless endoscope - or swallowable camera-pill - will serve as an example for which both approaches will be compared. Based on the conclusions of this comparison, an inductive link is realized and the predicted efficiency is verified through measurement.