Inductive device

An inductive device, comprising a substrate in the form of a foil of an electrically insulating material having a principal section (3) and first and second principal surfaces (1a, 1b), on the first and second principal surfaces of the principal section there being provided first and second patterns of conductor tracks, respectively, each pattern comprising a series of coil elements (7) in such a manner that opposite each coil element of the first pattern there is situated a coil element of the second pattern, each of said coil elements comprising a conductor track which extends spirally between an inner end (9) and an outer end (11), at least some of the coil elements being electrically interconnected in a two-by-two fashion by means of a connection track (13) which extends between the outer ends of the spirals, the connection tracks on each of the two principal surfaces extending opposite parts of the other principal surface which are free from connection tracks, said principal section being folded along folding lines (19) which extend between every two successive coil elements, in such a manner that the coil elements are situated in mutually parallel planes, characterized in that the spirals along which the conductor tracks of oppositely situated coil elements (7) of the first and the second pattern extend have the same winding direction and that the inner ends (9) of the spiral-shaped conductor tracks of oppositely situated coil elements of the first and the second pattern are electrically interconnected by means of interconnections (15) which extend between the first and second principal surfaces (1a, 1b).