Radio frequency identification transponder having a spiral antenna
First Claim
1. A radio-frequency identification transponder (RFID tag) comprising:
- a spiral antenna;
RF tag circuitry having at least one antenna input, the tag circuitry disposed on a substrate and electrically coupled to the spiral antenna, anda ground plane spaced from the spiral antenna by a predetermined distance, said spiral antenna thereby providing substantially circular polarization.
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Accused Products
Abstract
A radio frequency identification (RFID) transponder (tag) includes a spiral over ground plane antenna. The RFID tag includes a RFID circuitry that may be implemented as an RFID tag integrated circuit and may be mounted on one surface of a substrate such as a printed circuit board. The RFID tag circuitry may be electrically connected to an impedance matching circuit printed on the same side of printed circuit board. The matching circuit is electrically connected to a spiral antenna that may be mounted on same side of the printed circuit board as the tag circuit and matching circuit. The spiral antenna is held a prescribed distance from the ground plane in order to maximize the gain of the RFID tag and to thereby maximize the range of the RFID tag.
250 Citations
23 Claims
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1. A radio-frequency identification transponder (RFID tag) comprising:
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a spiral antenna; RF tag circuitry having at least one antenna input, the tag circuitry disposed on a substrate and electrically coupled to the spiral antenna, and a ground plane spaced from the spiral antenna by a predetermined distance, said spiral antenna thereby providing substantially circular polarization. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. An RFID system including:
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an RFID base station; and an RFID tag that includes a spiral antenna, RFID tag circuitry having at least one antenna input, the tag circuitry disposed on a substrate and electrically coupled to the spiral antenna, and a ground plane spaced from the spiral antenna by a predetermined distance, the spiral antenna thereby providing substantially circular polarization. - View Dependent Claims (14, 15, 16, 17, 18, 19, 20)
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21. A method of reading an RFID tag comprising the steps of:
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(a) transmitting a querying signal from an RFID base station; (b) receiving the querying signal by an RFID tag that includes a spiral antenna disposed over a ground plane, the spiral antenna providing substantially circular polarization; (c) modulating the received querying signal by the RFID tag; and (d) sending the modulated signal from the RFID tag to the base station. - View Dependent Claims (22, 23)
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Specification