AUTOMATIC SELECTIVE DAMPING OF A RESONANT ANTENNA

摘要

A damping control system disposed at a location of an antenna resonant circuit detects an exciter signal produced by a remotely located EAS transmitter. The damping control system generates a switch control signal in response to the detection of an EAS exciter signal burst. The switch control signal is used to reduce a Q factor of the antenna resonant circuit by selectively controlling at least one switching element connected to the antenna resonant circuit. The damping control system controls a timing of the switch control signal so as to reduce the Q factor at a predetermined time selected to reduce ringing at a trailing edge of each periodic burst.

主权项

1. An Electronic Article Surveillance (EAS) resonant antenna system with self-contained automatic selective damping, comprising:
an antenna resonant circuit responsive to an exciter signal produced by a remotely located EAS transceiver, the exciter signal comprised of a periodic burst of alternating current (AC) electrical energy which, when applied to the antenna resonant circuit, produce an electromagnetic field which is capable of exciting an EAS marker tag; a damping control system provided at the location of the antenna resonant circuit, remote from the EAS transceiver; wherein the damping control system detects each said periodic burst received at the antenna resonant circuit, and is responsive to said detecting to selectively decrease a Q factor of the antenna resonant circuit at a predetermined time.