Distributed RFID antenna array utilizing circular polarized helical antennas
First Claim
1. A radio frequency identification (RFID) system, comprising:
- a plurality of RFID tags, each of the plurality of RFID tags including a linear polarized antenna for communicating an RFID tag signal;
at least one receiver antenna for receiving the RFID tag signals, the receiver antenna including a circular polarized helical antenna element;
an RFID tag signal reader coupled to the at least one receiver antenna that processes the RFID tag signals;
a transmitter antenna for transmitting an RF signal to the RFID tag, the transmitter antenna including a circular polarized quadrifiler helical antenna element; and
a transmitter coupled to the at least one transmitter antenna that generates the RF signal;
wherein the RFID tag communicates the RFID tag signal in response to receiving the RF signal from the transmitter antenna;
wherein the plurality of RFID tags include a first tag and a second tag, the transmitter antenna being configured to apply a first gain on axis to the first tag and a second gain to the side of axis to the second tag, where the second gain is greater than the first gain.
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0 Petitions
Accused Products
Abstract
In accordance with the teachings described herein, RFID systems are provided that include a distributed RFID antenna array utilizing one or more circular polarized helical antennas. A plurality of RFID tags may be used, with each RFID tag including a linear polarized antenna for communicating RFID tag signals. One or more receiver antennas may be used for receiving the RFID tag signals from the RFID tags. An RFID tag signal reader may be used to process RFID tag signals received by the receiver antennas. In one example, the receiver antennas may include a circular polarized helical antenna element. One or more transmitter antennas may be used for transmitting an RF signal to the plurality of RFID tags, the transmitter antennas including a circular polarized helical antenna element. A transmitter may be used to generate the RF signal for transmission by the transmitter antennas. In one example, the RFID tag signal reader and the transmitter may be included in a single reader/transmitter unit.
383 Citations
26 Claims
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1. A radio frequency identification (RFID) system, comprising:
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a plurality of RFID tags, each of the plurality of RFID tags including a linear polarized antenna for communicating an RFID tag signal; at least one receiver antenna for receiving the RFID tag signals, the receiver antenna including a circular polarized helical antenna element; an RFID tag signal reader coupled to the at least one receiver antenna that processes the RFID tag signals; a transmitter antenna for transmitting an RF signal to the RFID tag, the transmitter antenna including a circular polarized quadrifiler helical antenna element; and a transmitter coupled to the at least one transmitter antenna that generates the RF signal; wherein the RFID tag communicates the RFID tag signal in response to receiving the RF signal from the transmitter antenna; wherein the plurality of RFID tags include a first tag and a second tag, the transmitter antenna being configured to apply a first gain on axis to the first tag and a second gain to the side of axis to the second tag, where the second gain is greater than the first gain. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19)
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20. A distributed radio frequency identification (RFID) antenna array system, comprising:
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at least one transmitter antenna for transmitting RF signals, the transmitter antenna including a circular polarized quadrifiler helical antenna element; a plurality of RFID tags, each of the plurality of RFID tags including a linear polarized antenna for receiving the RF signals and for transmitting RFID tag signals, the RFID tag signals being transmitted by the at least one of said plurality of RFID tags in response to receiving the RF signals; a plurality of receiver antennas for receiving the RFID tag signals from the at least one RFID tag; and a single reader/transmitter unit coupled to the at least one transmitter antenna and the plurality of receiver antennas, the reader/transmitter unit generating the RF signals for transmission by the at least one transmitter antenna and processing the RFID tag signals received by the plurality of receiver antennas; wherein the distributed RFID antenna array system is included within a designated area of a retail facility, the designated area including a plurality of sub-areas; wherein the plurality of RFID tags are located in the designated area with multiple RFID tags being located in each of the plurality sub-areas; wherein one of the plurality of receiver antennas is located in each of the plurality of sub-areas; wherein the at least one transmitter antenna is positioned to illuminate a plurality of RFID tags in each of the plurality of sub-areas with RF signals causing the one receiver antenna in each of the plurality of sub-areas to receive RFID tag signals from illuminated RFID tags; and wherein the at least one transmitter antenna is configured to apply a first gain on axis of the circular polarized quadrifiler helical antenna element and to apply a second gain off axis of the circular polarized quadrifiler helical antenna element, where the first gain is less than the second gain. - View Dependent Claims (21, 22, 23)
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24. A distributed radio frequency identification (RFID) antenna array system, comprising:
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at least one transmitter antenna for transmitting RF signals, the transmitter antenna including a circular polarized helical antenna element; a plurality of RFID tags, each RFID tag including a linear polarized antenna for receiving the RF signals and for transmitting RFID tag signals, the RFID tag signals being transmitted by the RFID tags in response to receiving the RF signals; a plurality of receiver antennas for receiving the RFID tag signals from the RFID tags; and means for generating the RF signals for transmission by the at least one transmitter antenna; and means for processing the RFID tag signals received by the plurality of receiver antennas; wherein the distributed RFID antenna array system is included within a designated area of a retail facility, the designated area including a plurality of sub-areas; wherein the plurality of RFID tags are located in the designated area with multiple RFID tags being located in each of the plurality of sub-areas; wherein one of the plurality of receiver antennas is located in each of the plurality of sub-areas; wherein the at least one transmitter antenna is positioned to illuminate RFID tags in each of the plurality of sub-areas with RF signals causing the one receiver antenna in each of the plurality of sub-areas to receive RFID tag signals from illuminated tags; and wherein the at least one transmitter antenna is configured to apply a first gain on axis of the circular polarized quadrifiler helical antenna element and to apply a second gain off axis of the circular polarized quadrifiler helical antenna element, where the first gain is less than the second gain. - View Dependent Claims (25, 26)
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Specification