Vector measuring aerial arrays for magnetic induction communication

Abstract

A wireless communication system automatically aligns a magnetic induction field to establish a two-way communication link between a stationary base unit located, for example, at a user's work station, and a remote unit worn by the user, for example, as a headset or body pack. At any point in time, the base unit and the remote unit have an arbitrary relative orientation to each other. The base unit senses this orientation, then aligns the magnetic induction field to maintain the communication link with the remote unit. In one embodiment, the base unit preferably includes an aerial array having a number of mutually orthogonal windings. Each winding produces a signal when a magnetic induction field generated by the remote unit passes through the base unit. A selector module selects the longitudinal axis of the winding with the strongest signal as an approximation of a direction vector defining the orientation of the magnetic induction field relative to the base unit. In another embodiment, the base unit preferably includes an aerial array comprising three orthogonal windings disposed about a spherical core. A selector module selects one or more windings for transmitting a magnetic field that rotates in a plane orthogonal, i.e., 'crossed field,' to the direction vector defining the orientation of the received field relative to the base unit.