6DOF Electromagnetic Tracker Electric Field

6DOF trackers exhibiting submillimeter error at range of half a meter, can be accuracy-limited by electric-field coupling from transmitter to receiver.

Magnetic charges do not exist, so the magnetic field exhibits dipole-dipole magnetic (inductive)coupling from transmitter to receiver, so the receiver signal is inversely proportional to the cube of range for ranges short compared to a wavelength (near-field regime).

Electric charges do exist, so the lowest-order electric (capacitive) coupling is monopole-monopole, giving receiver signal inversely proportional to range.

Electric_signal/magnetic_signal is thus proportional to the square of range, increasing at large ranges.

Thus, the angular error due to electric coupling is proportional to the square of range, increasing at larger ranges. The electric-coupling-caused transverse position error in millimeters is an angle times range so is proportional to the cube of range.

Electric coupling can be blocked by an electrically-slightly-conducting grounded shield layer surrounding the receiver.