| 摘要 |
The device comprises an electrically insulating substrate comprising a principal section (3). First and second principal surfaces (1a, 1b) of the principal section (3) support first and second pairs of conductor tracks, respectively. Each pattern comprises a series of coil elements (7), opposite each coil element of the first pattern there being situated a coil element of the second pattern. Each coil element (7) comprises a spiral-shaped conductor track, having an inner end (9) and an outer end (11), and some coil elements are electrically interconnected in a two-by-two fashion by means of a connection track (13) which extends between their outer ends, the connection tracks on each of the two principal surfaces extending opposite parts of the other principal surface which are free from connection tracks. The principal section (3) is folded, so that the coil elements are situated in mutually parallel planes. The spirals of oppositely situated coil elements (7) of the first and the second patterns have the same winding direction and their inner ends (9) are electrically interconnected by means of interconnections (15) which extend between the first and second principal surfaces (1a, 1b).
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