Microstrip antenna for RFID device
First Claim
1. A radio frequency identification transponder comprising:
- a microstrip patch antenna;
a first feed and a second feed, each feed being coupled with an edge of the microstrip patch antenna, and the first feed being approximately 180 degrees out of phase with the second feed; and
a matching circuit coupling the first and second feeds with an integrated circuit.
1 Assignment
0 Petitions
Accused Products
Abstract
Microstrip patch antenna (46), feed structure (48), and matching circuit (50) designs for an RFID tag (10). A balanced feed design using balanced feeds coupled by a shorting stub (56) to create a virtual short between the two feeds so as to eliminate the need for physically connecting substrate to the ground plane. A dual feed structure design using a four-terminal IC can be connected to two antennas (46a,46b) resonating at different frequencies so as to provide directional and polarization diversity. A combined near/field-far/field design using a microstrip antenna providing electromagnetic coupling for far-field operation, and a looping matching circuit providing inductive coupling for near-field operation. A dual-antenna design using first and second microstrip antennas providing directional diversity when affixed to a cylindrical or conical object, and a protective superstrate (66). An annual antenna (46c) design for application to the top of a metal cylinder around a stem.
55 Citations
30 Claims
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1. A radio frequency identification transponder comprising:
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a microstrip patch antenna; a first feed and a second feed, each feed being coupled with an edge of the microstrip patch antenna, and the first feed being approximately 180 degrees out of phase with the second feed; and a matching circuit coupling the first and second feeds with an integrated circuit. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. In a radio frequency identification transponder for physical association with an object and for storing and communicating data regarding the object, the radio frequency identification transponder having a microstrip patch antenna and an integrated circuit, the improvement comprising:
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a first feed and a second feed, each feed being coupled with an edge of the microstrip patch antenna, and the first feed being approximately 180 degrees out of phase with the second feed; and a matching circuit coupling the first and second feeds with the integrated circuit, the matching circuit including a transmission line coupling the first feed with the second feed and creating a virtual short between the feeds. - View Dependent Claims (9, 10, 11)
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12. A radio frequency identification transponder comprising:
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a first patch antenna and a second patch antenna; an integrated circuit having a first pair of terminals and a second pair of terminals; and a first matching circuit for coupling the first patch antenna to the first pair of terminals, wherein the first matching circuit resonates at a first frequency; and a second matching circuit for coupling the second patch antenna to the second pair of terminals, wherein the second matching circuit resonates at a second frequency. - View Dependent Claims (13, 14, 15)
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16. In a radio frequency identification transponder for physical association with an object and for storing and communicating data regarding the object, the improvement comprising:
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a first patch antenna and a second patch antenna; an integrated circuit having a first pair of terminals and a second pair of terminals; a first matching circuit for coupling the first patch antenna to the first pair of terminals wherein the first matching circuit resonates at a first frequency; and a second matching circuit for coupling the second patch antenna to the second pair of terminals, wherein the second matching circuit resonates at a second frequency. - View Dependent Claims (17, 18, 19)
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20. A radio frequency identification transponder comprising:
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a microstrip patch antenna having an annular shape with an inner edge and an outer edge; an integrated circuit; a first feed and a second feed, each feed being coupled with either edge of the microstrip patch antenna, and the first feed being approximately 180 degrees out of phase with the second feed; and a matching circuit coupling the first and second feeds with the integrated circuit, the matching circuit including a transmission line coupling the first feed with the second feed and creating a virtual short between the feeds. - View Dependent Claims (21, 22, 23, 24)
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25. In a radio frequency identification transponder for physical association with a cylindrical object having a stem and for storing and communicating data regarding the object, the radio frequency identification transponder having a microstrip patch antenna and an integrated circuit, the improvement comprising:
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the microstrip patch antenna having an annular shape with an inner edge and an outer edge; a first feed and a second feed, each feed being coupled with either edge of the microstrip patch antenna, and the first feed being approximately 180 degrees out of phase with the second feed; and a matching circuit coupling the first and second feeds with the integrated circuit, the matching circuit including a transmission line coupling the first feed with the second feed and creating a virtual short between the feeds, wherein the matching circuit is coupled with the inner edge of the microstrip patch antenna. - View Dependent Claims (26, 27)
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28. In a radio frequency identification transponder for physical association with a cylindrical object having a stem and for storing and communicating data regarding the object, the radio frequency identification transponder having a microstrip patch antenna and an integrated circuit, the improvement comprising:
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the microstrip patch antenna having an annular shape with an inner edge and an outer edge; a first feed and a second feed, each feed being coupled with either edge of the microstrip patch antenna, and the first feed being approximately 180 degrees out of phase with the second feed; and a matching circuit coupling the first and second feeds with the integrated circuit, the matching circuit including a transmission line coupling the first feed with the second feed and creating a virtual short between the feeds, wherein the matching circuit is coupled with the outer edge of the microstrip patch antenna. - View Dependent Claims (29, 30)
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Specification