摘要 |
A method is provided for detecting an article identification tag (30), which has at least one electrically conductive member (31-3n). For each electrically conductive member, an alternating electric current is caused to flow through the member. A frequency of the alternating electric current is varied, and a corresponding variation in impedance of the member is monitored. A discontinuity in the variation in impedance is detected, and the frequency of the alternating electric current is detected, i.e. the frequency at which the discontinuity appears. |