| 摘要 |
The reader or transmitter and/or receiver ( 22 ) includes a sheathed antenna formed of two groups of turns or coils ( 6, 8, 9; 16, 17 ). The first group of turns or coils forms a sheathed antenna. The second group includes two coils ( 16, 17 ) arranged between the central coil ( 6 ) and respectively the two end coils ( 8, 9 ) of the first group. The second group of coils is powered in phase quadrature relative to the first group of coils, the set of coils being arranged so as to obtain a magnetic field (H) whose amplitude (A) is approximately constant along the central axis ( 24 ) of the antenna inside the overall inner volume of the latter.
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