RFID system with distributed read structure
View Patent ↗A radio frequency identification (RFID) system includes a portable RFID reader, and a read infrastructure that includes a distributed read structure, which may be part of a display (such as a shelf) for holding objects. The read structure is used to couple the RFID reader to RFID devices (tabs and/or labels) on or near the structure. The RFID reader and the read structure communicate in a near field or proximity region communication, without any use of a direct ohmic electrical connection. The RFID reader may have an antenna that is configured for near field or proximity communication with a coupler of the read infrastructure. The RFID reader may also have a separate antenna for use in far field communication. The RFID reader may be able to obtain information more efficiently in the near field or proximity mode, allowing information to be received faster and with greater reliability.
1. A read infrastructure for radio frequency identification (RFID) devices comprising:
a distributed read structure for proximity coupling with RFID devices within one wavelength of radiation emitted by the read structure, the distributed read structure comprises a series of conductive strips or patterns on at least one surface of a display device, the conductive strips or patterns are configured to produce a radio frequency (RF) field between conductors for detecting the RFID device; and
a coupler, electrically connected to the read structure, for proximity coupling to an RFID reader wherein the RFID reader includes a first antenna and a second antenna such that either the first or second antenna is used for proximity coupling and whichever of the first and second antenna that is not used for proximity coupling is used for far field coupling and the RFID reader transmits on both the first and second antennas and utilizes the first or second antenna with a lowest return loss, such that the RFID reader transmits for proximity coupling using the first or second antenna with an acceptable return loss for proximity coupling; wherein the coupler includes a microstrip and interconnections from sides of the microstrip are used to connect the conductive strips or patterns to the distributed read structure.
2. The read infrastructure of claim 1 , wherein the coupler includes a central active patch or plane of conductive material, flanked by a pair of outer ground patches or planes of conductive material, the central active patch is coupled to a central conductor of the coaxial cable and the ground patches are coupled to an outer, ground conductor of the coaxial cable.
3. The read infrastructure of claim 1 , as part of a RFID system in combination with the RFID reader operatively coupled to the coupler.
4. The read infrastructure of claim 1 , wherein the RFID reader further comprises electronics for operating the RFID reader in two separate modes.
5. The read infrastructure of claim 4 , wherein the modes include a proximity mode in which the RFID reader communicates by proximity coupling and a far field mode in which the RFID reader communicates by far field coupling.
6. The read infrastructure of claim 1 , wherein the read infrastructure is part of a display device.
7. The read infrastructure of claim 1 , wherein the read structure is portable.
8. The read infrastructure of claim 1 , wherein either the first or second antenna is a half wave patch antenna.
9. The read infrastructure of claim 1 , further comprising a power amplifier.
10. The read infrastructure of claim 9 , wherein the power amplifier is a single direction unit.
11. The read infrastructure of claim 9 , wherein the power amplifier is a bi-directional amplifier.
12. The read infrastructure of claim 1 , wherein the first and second antennas are different types of antennas.