A passive, non-multiplexed, two-axis antenna for sensing time-varying magnetic fields of a particular carrier frequency at a second point in space as produced by a electromagnetic field generator located at a first point in space. The antenna has a particular sensitive plane and produces a single output...http://www.google.com/patents/US6538617?utm_source=gb-gplus-sharePatent US6538617 - Two-axis, single output magnetic field sensing antenna
