Variable frequency radio frequency identification (RFID) tags
First Claim
1. A radio-frequency identification (RFID) tag comprising:
- a main antenna tuned to a first resonant frequency;
switching circuitry that selectively changes the resonant frequency of the main antenna; and
an RFID integrated circuit electrically coupled to the main antenna that stores information relating to an article associated with the RFID tag and communicates the information to an RFID reader via the main antenna,wherein the switching circuitry comprises a low-power switch that requires less power to switch positions than is necessary for the RFID integrated circuit to communicate the information to the RFID reader.
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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.
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Citations
28 Claims
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1. A radio-frequency identification (RFID) tag comprising:
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a main antenna tuned to a first resonant frequency; switching circuitry that selectively changes the resonant frequency of the main antenna; and an RFID integrated circuit electrically coupled to the main antenna that stores information relating to an article associated with the RFID tag and communicates the information to an RFID reader via the main antenna, wherein the switching circuitry comprises a low-power switch that requires less power to switch positions than is necessary for the RFID integrated circuit to communicate the information to the RFID reader. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A method comprising:
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operating a main antenna of a radio frequency identification (RFID) tag at a first resonant frequency; and selectively changing the resonant frequency of the main antenna by automatically switching a position of a low-power switch with respect to one or more circuit elements, wherein the low-power switch requires less power to switch positions than is necessary for an RFID integrated circuit electrically coupled to the main antenna to communicate stored information to an RFID reader via the main antenna, and wherein selectively changing the resonant frequency comprises changing the resonant frequency of the antenna when the RFID tag receives enough power to activate the low-power switch but not to activate the integrated circuit. - View Dependent Claims (13, 14, 15, 16, 17, 18, 19)
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20. A radio frequency identification (RFID) system comprising:
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an RFID interrogation device; an RFID tag associated with an article, wherein the RFID interrogation device generates an RF field to interrogate the RFID tag to obtain information regarding the article; and a computing device to process the information retrieved from the RFID interrogation device, wherein the RFID tag includes a main antenna tuned to a first resonant frequency, an integrated circuit electrically coupled to the main antenna that stores the information and communicates the information to the RFID interrogation device via the main antenna, and switching circuitry that selectively couples one or more elements to the main antenna to adjust the resonant frequency of the main antenna, and wherein the switching circuitry comprises a low-power switch that requires less power to switch positions than is necessary for the RFID integrated circuit to communicate the information to the RFID interrogation device. - View Dependent Claims (21, 22, 23, 24, 25, 26, 27, 28)
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Specification