Abstract: Various radio frequency identification (RFID) tags are described that dynamically vary their resonant frequency to reduce or eliminate the potential effects of electromagnetic “tag-to-tag” coupling. An RFID tag, for example, includes a main antenna tuned to a first resonant frequency, and switching circuitry that dynamically changes the resonant frequency of the main antenna. The switching circuitry may selectively couple electrical elements, such as capacitive elements, inductive elements, or combinations thereof, to vary the resonant frequency of the RFID tag. The RFID tag may include a sensing circuit that determines when to selectively couple the electrical element to the main antenna to adjust the resonant frequency of the main antenna.

Abstract: A device for verifying a location of a radio-frequency identification (RFID) tag on an item. One embodiment of the invention provides a device for verifying the location of an RFID tag on an item including: an item holder; and an RF antenna attached to the item holder, where the item holder includes a readable volume where the RF antenna can read or write to an RFID tag, and where the item holder includes a non-readable volume where the RF antenna cannot read or write to an RFID tag. The present invention also relates to methods of verifying the location of a radio-frequency identification (RFID) tag on an item.

Abstract: Various radio frequency identification (RFID) tags are described that dynamically vary their resonant frequency to reduce or eliminate the potential effects of electromagnetic “tag-to-tag” coupling. An RFID tag, for example, includes a main antenna tuned to a first resonant frequency, and switching circuitry that dynamically changes the resonant frequency of the main antenna. The switching circuitry may selectively couple electrical elements, such as capacitive elements, inductive elements, or combinations thereof, to vary the resonant frequency of the RFID tag. The RFID tag may include a sensing circuit that determines when to selectively couple the electrical element to the main antenna to adjust the resonant frequency of the main antenna.

Abstract: Various radio frequency identification (RFID) tags are described that dynamically vary their resonant frequency to reduce or eliminate the potential effects of electromagnetic “tag-to-tag” coupling. An RFID tag, for example, includes a main antenna tuned to a first resonant frequency, and switching circuitry that dynamically changes the resonant frequency of the main antenna. The switching circuitry may selectively couple electrical elements, such as capacitive elements, inductive elements, or combinations thereof, to vary the resonant frequency of the RFID tag. The RFID tag may include a sensing circuit that determines when to selectively couple the electrical element to the main antenna to adjust the resonant frequency of the main antenna.

Abstract: A device for verifying a location of a radio-frequency identification (RFID) tag on an item. One embodiment of the invention provides a device for verifying the location of an RFID tag on an item including: an item holder; and an RF antenna attached to the item holder, where the item holder includes a readable volume where the RF antenna can read or write to an RFID tag, and where the item holder includes a non-readable volume where the RF antenna cannot read or write to an RFID tag. The present invention also relates to methods of verifying the location of a radio-frequency identification (RFID) tag on an item.

Abstract: Various radio frequency identification (RFID) tags are described that dynamically vary their resonant frequency to reduce or eliminate the potential effects of electromagnetic “tag-to-tag” coupling. An RFID tag, for example, includes a main antenna tuned to a first resonant frequency, and switching circuitry that dynamically changes the resonant frequency of the main antenna. The switching circuitry may selectively couple electrical elements, such as capacitive elements, inductive elements, or combinations thereof, to vary the resonant frequency of the RFID tag. The RFID tag may include a sensing circuit that determines when to selectively couple the electrical element to the main antenna to adjust the resonant frequency of the main antenna.

Abstract: The invention provides a multi-loop antenna that produces an electromagnetic field having a magnitude of at least an interrogation threshold of a tag for a substantial portion of an interrogation region located in a plane parallel to the antenna. The antenna may include a plurality of loops, including one or more powered loops and one or more parasitic loops. The parasitic loops receive power from mutual coupling with the powered loops causing current to flow within the parasitic loops, which contributes to the profile of the magnetic field. As a result, each parasitic loop may be tuned to provide control over the magnitude of the electromagnetic field. The powered loops and the parasitic loops may be varied over the interrogation period to reduce any area of the interrogation region where the magnitude of the field remains below the interrogation threshold throughout the interrogation period. The powered loops and the parasitic loops may reside on a single layer or may be arranged on multiple layers.

Abstract: The invention provides a multi-loop antenna that produces an electromagnetic field having a magnitude of at least an interrogation threshold of a tag for a substantial portion of an interrogation region located in a plane parallel to the antenna. The antenna may include a plurality of loops, including one or more powered loops and one or more parasitic loops. The parasitic loops receive power from mutual coupling with the powered loops causing current to flow within the parasitic loops, which contributes to the profile of the magnetic field. As a result, each parasitic loop may be tuned to provide control over the magnitude of the electromagnetic field. The powered loops and the parasitic loops may be varied over the interrogation period to reduce any area of the interrogation region where the magnitude of the field remains below the interrogation threshold throughout the interrogation period. The powered loops and the parasitic loops may reside on a single layer or may be arranged on multiple layers.

Abstract: Various systems and methods of handling items such as files are disclosed, including systems and methods for polling RFID-tagged items while they are stored in storage areas.

Abstract: Various systems and methods of handling items such as files are disclosed, including systems and methods for polling RFID-tagged items while they are stored in storage areas.