| 摘要 |
In a pulsed-signal magnetomechanical electronic article surveillance system, a single transmit circuit is used to drive two or more parallel-connected interrogation signal transmitting antennas. One or more switchable damping circuits are provided in series with the antennas to promote rapid damping of the interrogation signal at the end of each signal pulse. The damping circuit or circuits are situated to provide damping in the loop or loops formed by the parallel-connected antennas. Each switchable damping circuit is formed of a resistance connected between a respective antenna and a terminal of the transmit circuit, as well as a switching element connected across the resistance. The switching element is maintained in a conducting condition during each signal pulse and is open-circuited at the end of each pulse to bring the resistance into effective damping connection with the transmit antennas. |
