An apparatus includes a medical instrument, a sensor assembly, and a pair of wires. The sensor assembly is positioned at the distal end of the medical instrument. The sensor assembly includes a first coil member oriented along a first longitudinal axis and a second coil member oriented along a second longitudinal axis. The first and second coil members are coupled with each other in series. The first and second longitudinal axes are offset from each other. The first and second coil members are configured to generate electrical signals indicative of a position and orientation of the distal end of the medical instrument within a patient. First and second wires of the pair of wires are operable to communicate signals from the sensor assembly to a navigation system.
