RFID UHF stripline antenna-coupler
View Patent ↗A stripline antenna-coupler for a RFID system is provided. The coupler is configured to communicate with a targeted transponder from among a group of multiple adjacent transponders. The coupler may include at least two conductive strips, at least one terminating load, a dielectric material, a first ground plane, and a second ground plane. Each of the conductive strips extends between the first and second ground planes and the dielectric material from an input end connected to a transceiver to a loaded end connected to the terminating load. The conductive strips may be configured to propagate electromagnetic fields concentrated in a near field region of the conductive strips in a direction generally perpendicular to the conductive strips to couple with a targeted transponder. The coupler may include an enclosure for directing the electromagnetic fields. The conductive strip may have a tapered or non-linear profile such as a modified bow-tie profile.
1. A stripline antenna-coupler for a RFID enabled system having a transceiver, the antenna-coupler being adapted to couple a transceiver with a targeted transponder in a transponder encoding region from among a group of multiple adjacent transponders, the antenna-coupler comprising:
a first ground plane and a second ground plane spaced apart from each other;
at least one connection between the first ground plane and the second ground plane for connecting the first ground plane to the second ground plane;
a first conductive strip being positioned at least partially between the first and second ground planes and configured to propagate a plurality of electromagnetic fields; and
a second conductive strip being positioned at least partially between the first conductive strip and the second ground plane and configured to propagate a plurality of electromagnetic fields,
wherein the first ground plane, the second ground plane, and the at least one connection promote the propagation of the plurality of electromagnetic fields from a side of each of the first and second conductive strips, the stripline antenna-coupler is configured to propagate the electromagnetic fields from the side of each of the first and second conductive strips in a direction generally parallel to the first and second ground planes for coupling with the targeted transponder in the transponder encoding region.
2. The stripline antenna-coupler according to claim 1 further comprising a dielectric material positioned between the first ground plane and the second ground plane and at least partially around the first and second conductive strips.
3. The stripline antenna-coupler according to claim 2 , wherein the dielectric material is from the group consisting of a ceramic, a plastic, and a combination of ceramic and plastic.
4. The stripline antenna-coupler according to claim 2 , wherein the dielectric material is air.
5. The stripline antenna-coupler according to claim 1 , wherein the propagation of the plurality of electromagnetic fields from the side of each of the first and second conductive strips is in a direction generally perpendicular to a length of the first and second conductive strips.
6. The stripline antenna-coupler according to claim 1 , wherein the antenna-coupler is a near field antenna-coupler and the plurality of electromagnetic fields are concentrated in a near field region of the conductive strip.
7. The stripline antenna-coupler according to claim 6 further comprising an input port for connecting the antenna-coupler to the transceiver and at least a first terminating load and a second terminating load, wherein the at least first and second terminating loads divided by a number of conductive strips of the stripline antenna-coupler define an input impedance and wherein the input impedance is substantially equal to a source impedance of the transceiver and wherein each conductive strip extends from a first end connected to the input port and a second end connected to one of the at least first and second terminating loads, wherein the first end and second end of the first conductive strip defines a length for the first conductive strip and the first end and second end of the second conductive strip defines a length for the second conductive strip.
8. The stripline antenna-coupler according to claim 6 further comprising an input port for connecting the antenna-coupler to the transceiver and a terminating load defining an input impedance, wherein the input impedance is substantially equal to a source impedance of the transceiver and wherein each conductive strip extends from a first end connected to the input port and a second end connected to the terminating load, wherein the first end and second end of the first conductive strip defines a length for the first conductive strip and the first end and second end of the second conductive strip defines a length for the second conductive strip.
9. The stripline antenna-coupler according to claim 1 , wherein the antenna-coupler is configured to operate within a band of frequencies and each of the first and second conductive strips defines a width that remains substantially constant along a length of the conductive strip and the length of the conductive strip is substantially equal to a half wavelength of a center frequency of the band of frequencies.
10. The stripline antenna-coupler according to claim 1 , wherein the antenna-coupler is configured to operate within a band of frequencies and each of the first and second conductive strips defines a width that varies along the length of the conductive strip and defines a tapered profile and the length of the conductive strip is less than a half wavelength of a center frequency of the band of frequencies.
11. The stripline antenna-coupler according to claim 10 , wherein the tapered profile is a modified bow-tie profile.
12. The stripline antenna-coupler according to claim 10 , wherein the tapered profile is selected from the group consisting of an exponential profile, a triangular profile, a Klopfenstein profile, and a Hecken profile.
13. The stripline antenna-coupler according to claim 1 , wherein each of the first and second conductive strips defines a length; wherein the length of the first conductive strip is shorter than a resonant length of the conductive strips and the length of the second conductive strip is longer than the resonant length of the conductive strips.
14. The stripline antenna-coupler according to claim 1 further comprising a third conductive strip.
15. The stripline antenna-coupler according to claim 1 further comprising a plurality of connections between the first ground plane and the second ground plane, wherein the connections extend substantially around each of the first and second conductive strips and define one active side of the antenna-coupler free of connections and configured to promote the propagation of the electromagnetic fields from the active side for coupling with the targeted transponder.
16. An RFID system for selectively communicating with a targeted transponder from among a group of multiple adjacent transponders, the RFID system comprising:
a transponder conveyance system adapted to transport at least one targeted transponder from a group of multiple adjacent transponders through a transponder encoding region along a predetermined path; and
an antenna-coupler including a first conductive strip, a second conductive strip, a first ground plane, and a second ground plane, wherein each of the first and second conductive strips is positioned at least partially between the first and second ground planes and is configured to propagate an electromagnetic field to the transponder encoding region for communicating with the targeted transponder, the antenna-coupler configured to propagate the electromagnetic field in a direction generally parallel to the first and second ground planes for communicating with the targeted transponder in the transponder encoding region.
17. The RFID system according to claim 16 further including a transceiver configured to generate communication signals, wherein the transceiver is in electrical communication with the antenna-coupler.
18. The RFID system according to claim 17 , wherein the antenna-coupler further includes a dielectric material positioned between the first ground plane and the second ground plane and at least partially around the first and second conductive strips.
19. The RFID system according to claim 18 , wherein the antenna-coupler is a near field antenna-coupler configured to create a plurality of electromagnetic fields concentrated in a near field region of the antenna-coupler.
20. The RFID system according to claim 19 , wherein the near field antenna-coupler further includes a first terminating load and a second terminating load, and each of the first and second conductive strips extends from an input end connected to the transceiver to a loaded end connected to the at least one of the first and second terminating loads and between a first side edge and a second side edge, wherein the input end and the loaded end define a length of the conductive strip and the first side edge and the second edge define a width the conductive strip, and the width of the conductive strip is generally perpendicular to the targeted transponder during coupling.
21. The RFID system according to claim 16 , wherein the first conductive strip is positioned at least partially between the first ground plane and the second conductive strip.