Application (pre-grant publication)
HIGH-Q AND OVER-COUPLED NEAR-FIELD RFID READER ANTENNA FOR IMPROVED TAG READ RANGE
- Number
- 20170323501
- Published
- 2017-11-09
- Filed
- 2017-05-03
- Assignee
- DISNEY ENTERPRISES, INC.
- Inventors
- SAMPLE; ALANSON
- CPC
- G06K19/0723; G06K19/07762; G06K7/10148; G06K7/10366; G06K7/10415; G07C9/00309; G07C9/28; H04B5/266
- Verdict
- Low Hardware
- Source
- Google Patents · FreePatentsOnline
The keeper's note
An RFID reader antenna design using impedance matching to improve tag read range via an over-coupled near-field configuration.
Abstract
An RFID system in which at least one of the RFID tag antenna and the RFID reader antenna has an impedance matching network associated therewithin order to better match the impedances of the two antennas. This impedance matching places the antennas into an over-coupled regime once they are within a reasonable distance of each other (e.g., 2 to 50 mm). It also increases the Q-factor of the improved antenna, which can greatly increase the range at which the RFID reader can read the RFID tag. This improved RFID system may be used in any of a variety of application, including operating a door lock mechanism.
Background
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a block diagram of an RFID system.
FIG. 2 is a block diagram of a first embodiment of selected components of an RFID system.
FIG. 3 is a block diagram of a second embodiment of selected components of an RFID system.
FIG. 4 is a block diagram of a third embodiment of selected components of an RFID system.
FIG. 5 is a schematic view of an antenna and impedance matching network of an RFID readerof the RFID system of FIG. 1.
FIG. 6 is schematic view of an antenna and impedance matching network of an RFID tag of the RFID system of FIG. 1.
FIG. 7 is a simplifiedillustration of a door with a door lock and latch mechanism, from a generally horizontally-oriented view.
FIG. 8 is a simplified illustration of the door with the door lock and latch mechanism of FIG. 7, from a generally vertically-oriented view.
FIG. 9 is a simplified illustration of a wristband worn by a user, the wristband containing an RFID tag.
FIG. 10 is a circuit schematic showing tuning circuit for reader and tag antennas and also the RFID chip lumped model
FIG. 11(a) is a Smith chart illustrating impedance variation over frequency for OC and CC resonators, with high and low Q values. FIG. 11(b) shows a graph of the magnitude of the transmission coefficient, S.sub.21 corresponding to the impedances plotted in FIG. 11(a). In this example, the coupling coefficient, k=0:005. The square, asterisk, and triangle