| 摘要 |
PCT No. PCT/SE87/00015 Sec. 371 Date Sep. 15, 1987 Sec. 102(e) Date Sep. 15, 1987 PCT Filed Jan. 16, 1987 PCT Pub. No. WO87/04551 PCT Pub. Date Jul. 30, 1987.A receiving device for detecting the presence of an indicating device in a restricted investigation zone, where coils and associated feed and receiving equipment are provided to emit and receive magnetic alternating fields in order thereby to detect the presence of an indicating device in the investigation zone, which indicating device is capable to receive alternating fields and to re-emit an alternating field. Said receiving coils for receiving said re-emitted alternating field comprise at least two coil sets (10,10',10''), each of which constitutes a so-called balanced coil wound to a configuration corresponding to two substantially rectangular eights located to the side of each other in the same plane. The coil sets (10,10',10'') are located in parallel with each other, preferably in the same plane, where each of the coil sets (10,10',10'') is offset, relative to an adjacent coil set, in a direction in parallel with said plane through a distance corresponding to about one fourth of the distance (2a) in the offset direction between the outer opposed sides (18,11;14,15) in a coil set (10).
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