Apparatus for determining a location of a target, the apparatus comprising: first and second magnetic dipole beacons positioned at substantially a same spatial location having respectively first and second time dependent magnetic moments oriented in different directions that generate first and second magnetic fields having different time dependencies； at least one magnetic field sensor coil located at the location of the target that generates signals responsive to the first and second magnetic fields； and circuitry that receives the signals generated by the at least one sensor coil and processes the signals responsive to the different time dependencies of the magnetic fields to determine a location of the at least one sensor coil and thereby the target.
