A security tag detection and localization system for detecting a resonant security tag in a security zone comprising a Plurality of detection zones, and generating an alarm signal localizing the resonant security tag to a detection zone. The system includes an antenna array for radiating interrogation signals and receiving response signals. The antenna array forms the upper boundary, the lower boundary or both the upper and lower boundaries of a security zone and extends horizontally across the width and length of the security zone. The antenna array comprises at least two antennas. The antennas forming the upper and lower boundaries are disposed side-by-side in a single horizontal plane with each antenna being electromagnetically coupled to one of the detection zones. The security tag detection and localization system also includes one or more electronic article security (EAS) sensors for transmitting interrogation signals to the antenna array, receiving response signals from the antenna array, and generating an alarm signal. The security tag detection and localization system also includes an annunciator connected to each EAS sensor, for receiving the alarm signal and indicating a detection zone corresponding to the alarm signal.

A radio frequency identification (RFID) device (12) having displacement current control. The RFID device (12) comprises a voltage source (30), and exciter electrode, electronic circuitry, a displacement current control surface (74) and a dielectric. The voltage source has a current return node. The exciter electrode is coupled to the voltage source. The displacement current control surface (74) is placed between the exciter electrode and the electronic circuitry. The dielectric is positioned between the displacement current control surface and the electronic circuitry, wherein the displacement current control surface is electrically terminated to the current return node of the voltage source.

An object identification system includes a monitor and a plurality of transceivers that communicate over a common medium. The monitor includes a first transmitter, a first receiver, and a processor. Each transceiver includes a resonant circuit, a transmitter, a receiver, and an antenna coupled to the resonant circuit. The processor performs a method for performing transceiver communication that includes the steps of: (a) transmitting from the first transmitter a first frequency for a first duration; (b) after lapse of the first duration, receiving via the first receiver a response signal from at least one of the resonant circuits; (c) determining a second frequency from the received response signal; and (d) performing transceiver communication using the second frequency. Transceivers of the type having a resonant circuit coupled to an antenna, when operating in close proximity to each other, may interfere with the response from a single transceiver by absorbing the energy intended to be received by the transceiver, absorbing the energy transmitted by the transceiver, or altering the resonant frequency of the resonant circuit. By determining the second frequency for transceiver communication, the monitor may establish communication with the single transceiver at a frequency better suited for transferring operative power to the transceiver, conducting an interrogation protocol for identifying the transceiver, or for data transfer.

A system for generating a magnetic field for excitation of a leadless marker assembly. The system of at least one embodiment includes a source generator that generates a plurality of alternating electrical signals each having an independently adjustable phase. A plurality of excitation coils are configured to simultaneously receive a respective one of the alternating electrical signals at a selected phase to generate a magnetic field. The phase of the alternating electrical signal for each excitation coil is independently adjustable relative to the phase of the alternating electrical signal for the other excitation coils so as to adjust the magnetic field from the respective coil. The magnetic fields from the excitation coils combine to form a spatially adjustable excitation field for excitation of the remote leadless marker assembly.

A system for generating a pulsed excitation field for excitation of a leadless marker assembly. One aspect of the system comprises a source generator assembly having a power supply, an energy storage device, a switching network and a source coil interconnected and configured to deliver a pulsed magnetic excitation signal waveform. The power supply is configured to deliver power to energize the energy storage device. The switching network is configured to: direct electrical current through the source coil; alternately switch between a first on position and a second on position; switch to an off position to prevent energy transfer from the energy storage device to the source coil; alternately transfer stored energy from the energy storage device to the source coil and to transfer stored energy from the source coil back to the energy storage device; and the source coil being coupled to the switching network to generate a pulsed excitation signal.