Abstract: An electromagnetic method for sensing the relative position of two items using coupled tuned resonant circuits. Two co-resonant tuned circuits are attached to two items 1 and 2 that move relative to one another. The coupling between the circuits is arranged to vary with their relative physical position. One of the tuned circuits is excited at or close to its resonant frequency. The degree of coupling between the tuned circuits is detected by its effect on the way the resultant oscillation changes with time, and this allows the relative position of the items to be established. The inductive elements of the tuned circuits can comprise anti-symmetrical regions 3, 4, 9 and 10 so that the magnetic fields generated by the oscillations are localised and sensitivity to externally applied magnetic fields is minimised. The inductive elements can be implemented directly as printed circuit board tracks.