Spatially selective UHF near field microstrip coupler device and RFID systems using device
View Patent ↗A system having a UHF RFID transceiver is adapted to communicate exclusively with a single electro-magnetically coupled transponder located in a predetermined confined transponder operating region. The system includes a near field coupling device comprising a plurality of lines connected in parallel with an unmatched load. The near field coupling device may be formed, for example on a printed circuit board with a plurality of electrically interconnected traces and a ground plane. The system establishes, at predetermined transceiver power levels, a mutual electro-magnetic coupling which is selective exclusively for a single transponder located in a defined transponder operating region. Also included are methods for selective communication with the transponder in an apparatus such as a printer-encoder.
1. A printer including a transceiver adapted to communicate with transponders, comprising:
a printhead;
a media conveyance adapted to transport a series of discrete media to said printhead and through a transponder operating region, at least some of said media including a transponder;
a near field coupler configured to generate a near field effect to couple with the transponder for data transfer;
the near field coupler having a plurality of lines electrically interconnected in parallel, and a spaced away ground plane.
2. The printer defined by claim 1 wherein the near field coupler is formed as traces on a printed circuit board.
3. The printer defined by claim 1 wherein the near field coupler has a characteristic impedance and the near field coupler is terminated by a terminating resistor having a different characteristic impedance.
4. The printer defined by claim 1 wherein the plurality of lines are arranged parallel to each other.
5. The printer defined by claim 1 wherein at least one of the plurality of lines has a zig-zag configuration.
6. The printer defined by claim 1 wherein said printhead is positioned and configured to print on or adjacent said transponder while it is still in said transponder operating region.
7. The printer defined by claim 1 wherein said printhead is positioned and configured to print on or adjacent said transponder when it is outside of said transponder operating region.
8. The printer defined by claim 1 adapted to feed a web of spaced transponders through said transponder operating region, and wherein said printer communicates with a transponder located in said transponder operating region but concurrently not with another transponder located outside of said transponder operating region.