Abstract: An alternating current (a.c.) field measurement system and method are disclosed. The system comprises an arrangement 6 for inducing an a.c. field in a conductor 2 and a sensor, for example coil 8, responsive to the a.c. field to produce a signal indicative of the a.c. field. The system further comprises circuitry 18 configured to apply a phase shift to the signal by an amount suitable to reduce a component of the signal dependent on the distance of the sense coil 8 from the conductor 2. The circuitry may be implemented by digital circuitry and/or analogue circuitry.