RFID tag reading system and method
View Patent ↗An embodiment of the present invention provides an RFID tag reading system, comprising an antenna system associated with a portal through which said RFID tag may pass, said antenna system comprising: a plurality of non-uniformly spaced antenna elements arranged substantially linearly; a power divider for dividing transmit power thereby coupling signals to said plurality of antenna elements; and a beamforming network capable of phase shifting the signals between the power divider and the plurality of antenna elements such that radiated signals from each antenna element add coherently such that the radiated electromagnetic energy is focused at a focal point in the near field region or in the Fresnel region of said antenna system.
1. a RFID tag reading system, comprising:
an antenna system associated with a portal through which a RFID tag may pass, said antenna system comprising:
a plurality of non-uniformly spaced antenna elements arranged substantially linearly;
a power divider for dividing transmit power thereby coupling signals to said plurality of antenna elements; and
a beamforming network adapted to phase shift the signals between the power divider and the plurality of antenna elements such that radiated signals from each antenna element add coherently such that the radiated electromagnetic energy is focused at a focal point in the near field region or in the Fresnel region of said antenna system.
2. The RFID tag reading system of claim 1 , further comprising at least one additional receive antenna element adapted to receive signals backscattered from at least one RFID tag located in the near field of said antenna system.
3. The RFID tag reading system of claim 1 , wherein said portal is a doorway and said antenna system is installed at the sides or the top said doorway.
4. The RFID tag reading system of claim 1 , wherein said antenna elements are arranged in a linear array along an axis, and where the axis is vertically oriented thereby allowing the near field beam to be broad in the horizontal direction which in turn allows greater dwell times for said RFID tags to be interrogated as it passes through said portal.
5. a RFID tag reading system, comprising:
an antenna system associated with a conveyor on which an RFID tag may pass, said antenna system comprising:
a plurality of antenna elements arranged in essentially an arc where the main beam of each element is directed toward the interior side of the arc;
a power divider for dividing transmit power thereby coupling signals to said plurality of antenna elements; and
a beamforming network adapted to phase shifte the signals between the power divider and the plurality of antenna elements such that radiated signals from each antenna element add coherently such that the radiated electromagnetic energy is focused at a focal point in the near field region or in the Fresnel region of said antenna system.
6. The RFID tag reading system of claim 5 , further comprising at least one additional receive antenna element adapted to receive signals backscattered from at least one RFID tag located in the near field of said focused array.
7. The RFID tag reading system of claim 6 , wherein said an antenna system is adapted to produce M fixed beams where each of N radiating elements is fed by an M-way power combiner, and M separate beamforming networks connect M RF input ports to each of said N M-way power combiners.
8. a RFID tag reading system, comprising:
at least one RFID tag reader;
at least one RFID tag with one or more electrically reflective surfaces placed around a volume where said at least one RFID tag is to be interrogate;
a plurality of antenna elements arranged in essentially an arc where the main beam of each element is directed toward the interior side of the arc
a power divider for dividing transmit power thereby coupling signals to said plurality of antenna elements; and
a beamforming network adapted to phase shift the signals between the power divider and the plurality of antenna elements such that radiated signals from each antenna element add coherently such that the radiated electromagnetic energy is focused at a focal point in the near field region or in the Fresnel region of said antenna system.
9. The RFID tag reading system of claim 8 , further comprising at least one additional receive antenna element adapted to receive signals backscattered from at least one RFID tag located in the near field region or Fresnel region of said antenna system.
10. The RFID tag reading system of claim 8 , wherein said antenna system is adapted to produce M fixed beams where each of N radiating elements is fed by an M-way power combiner, and M separate beamforming networks connect M RF input ports to each of said N M-way power combiners.
11. The RFID tag reading system of claim 8 , further comprising an antenna system, said antenna system comprising:
a plurality of non-uniformly spaced antenna elements arranged substantially linearly;
a power divider for dividing transmit power thereby coupling signals to said plurality of antenna elements; and
a beamforming network adapted to phase shift the signals between the power divider and the plurality of antenna elements such that radiated signals from each antenna element add coherently such that the radiated electromagnetic energy is focused at a focal point in the near field region or in the Fresnel region of said antenna system.
12. The RFID tag reading system of claim 11 , further comprising at least one additional receive antenna element adapted to receiveing signals backscattered from at least one RFID tag located in the near field of said antenna system.
13. The RFID tag reading system of claim 8 wherein said reflective surface comprises a substantially flat surface covered by conductive foil.
14. The RFID tag reading system of claim 8 , wherein said reflective surface comprises a substantially flat surface covered by conductive paint.
15. The RFID tag reading system of claim 8 , wherein said reflective surface comprises a conductive polymer material.
16. The RFID tag reading system of claim 8 , further comprising a beam scanning antenna system for interrogation of tags.
17. A method of reading a RFID tag, comprising:
passing said RFID tag through a portal associated with an antenna system, said antenna system comprising:
a plurality of non-uniformly spaced antenna elements arranged substantially linearly;
a power divider for dividing transmit power thereby coupling signals to said plurality of antenna elements; and
a phase shifter adapted to phase shift the signals between the power divider and the plurality of antenna elements such that radiated signals from each antenna element add coherently such that the radiated electromagnetic energy is focused at a focal point in the near field region or in the Fresnel region of said antenna system.
18. The method of claim 17 , further comprising receiving signals backscattered from said at least one RFID tag located in the near field of said antenna system by at least one additional receive antenna element.
19. A method of reading a RFID tag, comprising:
passing said RFID tag through a portal associated with an antenna system, said antenna system comprising:
a plurality of antenna elements arranged in essentially an arc where the main beam of each element is directed toward the interior side of the arc;
a power divider for dividing transmit power thereby coupling signals to said plurality of antenna elements; and
a beamforming network adapted to phase shift the signals between the power divider and the plurality of antenna elements such that radiated signals from each antenna element add coherently such that the radiated electromagnetic energy is focused at a focal point in the near field region or in the Fresnel region of said antenna system.
20. The method of claim 19 , further comprising receiving signals backscattered from said at least one RFID tag located in the near field of said antenna system by at least one additional receive antenna element.
21. A method of reading a RFID tag, comprising providing at least one RFID tag reader;
placing one or more electrically reflective surfaces around a volume where at least one RFID tag is to be interrogated; and
using an antenna system that comprises:
a plurality of antenna elements arranged in essentially an arc where the main beam of each element is directed toward the interior side of the arc;
a power divider for dividing transmit power thereby coupling signals to said plurality of antenna elements; and
a phase shifter adapted to shift the signals between the power divider and the plurality of antenna elements such that radiated signals from each antenna element add coherently such that the radiated electromagnetic energy is focused at a focal point in the near field region or in the Fresnel region of said antenna system.