Abstract: Microstrip patch antenna (46), feed structure (48), and matching circuit (50) designs for an RFID tag (10) are disclosed. A balanced feed design using balanced feeds coupled by a shorting stub (56) creates a virtual short between the two feeds so as to eliminate the need for physically connecting the substrate to the ground plane. A dual feed structure design uses a four-terminal IC connected to two antennas (46a,46b) resonating at different frequencies to provide directional and polarization diversity. A combined near-field/far-field design using a microstrip antenna provides electromagnetic coupling for far-field operation, and a looping matching circuit provides inductive coupling for near-field operation. A dual-antenna design uses first and second microstrip antennas providing directional diversity when affixed to a cylindrical or conical object, and a protective superstrate (66) is applied. An annular antenna (46c) design for application to the top of a metal cylinder around a stem is disclosed.

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 the 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 annular antenna (46c) design for application to the top of a metal cylinder around a stem.

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 the 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 annular antenna (46c) design for application to the top of a metal cylinder around a stem.

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 the 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 annular antenna (46c) design for application to the top of a metal cylinder around a stem.

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 the 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 annular antenna (46c) design for application to the top of a metal cylinder around a stem.

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.

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.