Inductive coil array

An inductive coil array 6, for determining a shape of an object 10, comprises an active coil 7, for providing an output signal through an output connection 9 and one or more passive coils 9, magnetically coupled to the active coil. The inductive coil array, e.g. eddy current array, may comprise a flexible material arranged to mechanically couple the plurality of inductive coils to each other. The array may comprise of two or less than 10 coils. Each inductive coil may comprise a ferromagnetic core and each passive coils may be connected to an individual capacitive load or to a common capacitive load. In use, the active coil is driven over a range of frequencies, preferably including a nominal resonant frequency of the active coil, and the response measured to determine the shape of the object. The determining step may comprise determining the angle between the passive and active coils