RFID near-field antenna and associated systems

1. A 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 configured to transport at least one targeted transponder from a group of multiple adjacent transponders through a transponder encoding area along a feeding path; and

an antenna configured to transmit an electromagnetic wave to the transponder encoding area for communicating with the targeted transponder, and the antenna includes at least a first ground plane, a second ground plane, a dielectric substrate, and a conductive strip,

wherein the first ground plane and the second ground plane extend along the dielectric substrate and the conductive strip extends between the first ground plane and the second ground plane, such that first ground plane and the conductive strip define a first slot extending between the first ground plane and the conductive strip and such that the second ground plane and the conductive strip define a second slot extending between the second ground plane and the conductive strip,

wherein the first ground plane, the second ground plane, and the conductive strip are substantially coplanar,

wherein the antenna is configured to operate within a band of frequencies and the conductive strip defines an electrical a length substantially equal to a multiple of one-half of a wavelength of a center frequency of the band of frequencies, and

wherein the first slot defines a distance between the conductive strip and the first ground plane, the distance varying along the length.

2. The RFID system according to claim 1 further including a reader configured to provide bi-direction communication with the targeted transponder through the antenna.

3. The RFID system according to claim 1 , wherein the antenna further includes a terminating load and an RF port and the conductive strip extends from a signal end of the conductive strip connected to the reader through the RF port to a loaded end of the conductive strip connected to the terminating load.

4. The RFID system according to claim 1 , wherein the first slot defines a first width profile and the second slot defines a second width profile, and wherein the first width profile and the second width profile are symmetrical along the length of the conductive strip.

5. The RFID system according to claim 4 , wherein the second width varies along at least a portion of the conductive strip.

6. The RFID system according to claim 1 , wherein the antenna includes a third ground plane opposite the dielectric substrate from the first and second ground planes and the conductive strip.

7. The RFID system according to claim 1 , wherein the antenna further includes a phase inverter configured to generate two signals, each 180 degrees out of phase with each other, to the conductive strip and the first and second ground planes such that a voltage applied between the conductive strip and the first ground plane has an inverse phase in regards to a voltage applied between a conductive strip and the second ground plane.

8. The RFID system according to claim 1 , wherein the first slot defines a slot width profile and the conductive strip defines a strip width profile, and wherein the slot width profile is at least one tenth the strip width profile.

9. The RFID system according to claim 1 , wherein the antenna creates a standing wave ratio having a value of at least two.

10. The RFID system according to claim 1 , wherein the dielectric substrate includes a ferrite combined with ceramic to increase permittivity and permeability to achieve miniaturization of the antenna.

11. A printer-encoder for printing and encoding a series of media units wherein at least one media unit includes at least one transponder, the printer encoder comprising:

a printhead for printing indicia onto the media units;

a conveyance system configured to transport a series of media units including the at least one transponder to the printhead and a transponder encoding area along a feed path in a feed direction;

a reader configured to process one or more communication signals; and

an antenna configured to direct the communication signals to and from the reader and the antenna is configured to communicate with the at least one transponder in the transponder encoding area and includes at least a first ground plane, a second ground plane, a dielectric substrate, and a conductive strip,

wherein the first ground plane and the second ground plane extend along the dielectric substrate and the conductive strip extends between the first ground plane and the second ground plane such that first ground plane and the conductive strip define a first slot extending between the first ground plane and the conductive strip and such that the second ground plane and the conductive strip define a second slot extending between the second ground plane and the conductive strip,

wherein the first ground plane, the second ground plane, and the conductive strip are substantially coplanar, the conductive strip defining a length, and

wherein the first slot defines a distance between the conductive strip and the first ground plane, the distance varying along the length.

12. The printer-encoder according to claim 11 further comprising a platen roller and a ribbon guide, wherein the ribbon guide is configured to direct a portion of a thermal ribbon between the printhead and the platen roller and the printhead is configured to provide heat and press against the portion of the thermal ribbon again the platen roller such that indicia is formed on a media unit between the platen roller and the printhead.

13. The printer-encoder according to claim 12 , wherein the ribbon guide defines a recessed portion configured to receive the antenna.

14. The printer-encoder according to claim 13 , wherein the antenna further includes a terminating load and a RF port and the conductive strip extends from a signal end of the conductive strip connected to the reader through the RF port to a loaded end of the conductive strip connected to the terminating load.

15. The printer-encoder according to claim 14 , wherein the first slot defines a first width profile and the second slot defines a second width profile, and wherein the first width profile and the second width profile are symmetrical along the length of the conductive strip.

16. The printer-encoder according to claim 15 , wherein the second width varies along at least a portion of the conductive strip.

17. The printer-encoder according to claim 11 , wherein the antenna includes a third ground plane opposite the dielectric substrate from the first and second ground planes and the conductive strip.

18. A printer-encoder for printing and encoding at least one media unit that includes a transponder, the printer encoder comprising:

a printhead for printing indicia onto the media units;

a platen roller;

a ribbon guide configured to direct a portion of a thermal ribbon between the printhead and the platen roller and the printhead is configured to provide heat and press the portion of the thermal ribbon against the platen roller such that indicia is formed on the least one media unit positioned between the platen roller and the printhead; and wherein the ribbon guide defines a recessed portion; and

an antenna positioned within the recessed portion and configured to transmit an electromagnetic wave for communicating with the transponder of the at least one media unit.

19. The printer-encoder according to claim 18 ,

wherein the antenna includes at least a first ground plane, a second ground plane, a dielectric substrate, and a conductive strip,

wherein the first ground plane and the second ground plane extend along the dielectric substrate and the conductive strip extends between the first ground plane and the second ground plane such that first ground plane and the conductive strip define a first slot extending between the first ground plane and the conductive strip, and the second ground plane and the conductive strip define a second slot extending between the second ground plane and the conductive strip, and

wherein the first ground plane, the second ground plane, and the conductive strip are substantially coplanar.

20. The printer-encoder according to claim 19 further including a reader configured to process communication signals, and wherein the antenna further includes a terminating load and a RF port and the conductive strip extends from an signal end of the conductive strip connected to the reader through the RF port to a loaded end of the conductive strip connected to the terminating load.

21. The printer-encoder according to claim 20 , wherein the first slot defines a first width and the second slot defines a second width, and wherein the first width and the second width are symmetrical along the length of the conductive strip.

22. The printer-encoder according to claim 21 , wherein each of the first width and the second width varies along at least a portion of the conductive strip.

23. The printer-encoder according to claim 21 , wherein the antenna includes a third ground plane opposite the dielectric substrate from the first and second ground planes and the conductive strip.

24. A method comprising:

providing an antenna that includes at least a first ground plane, a second ground plane, a dielectric substrate, and a conductive strip,

wherein the first ground plane and the second ground plane extend along the dielectric substrate and the conductive strip extends between the first ground plane and the second ground plan; such that first ground plane and the conductive strip define a first slot extending between the first ground plane and the conductive strip and such that the second ground plane and the conductive strip define a second slot extending between the second ground plane and the conductive strip, and

wherein the first ground plane, the second ground plane, and the conductive strip are substantially coplanar;

transporting a targeted transponder of the plurality of transponders along the feed path into the transponder encoding area; and

sending one or more electrical signals to the antenna such that the conductive strip and the first slot and the second slot emit an electromagnetic wave into the transponder encoding area for communicating with the targeted transponder in the transponder encoding area,

wherein the conductive strip defines a length, and

wherein the first slot defines a distance between the conductive strip and the first ground plane, the distance varying along the length.

25. The method of claim 24 further comprising printing indicia onto a media unit, wherein the targeted transponder is attached to the media unit.

26. The method of claim 24 further comprising providing a reader connected with the antenna and configured to generate and receive the one or more electrical signals.

27. The method of claim 24 , wherein the operation of transporting the targeted transponder into the transponder encoding area further includes aligning a center of the transponder with an end of the conductive strip of the antenna.

28. The method of claim 24 providing a first signal and a second signal 180 degrees out of phase with the first signal to the conductive strip and the first and second ground planes such that a voltage applied between the conductive strip and the first ground plane has an inverse phase in regards to a voltage applied between a conductive strip and the second ground plane.