Printed RFID tag antenna array with interfering subarrays

• US 10,311,264 B1
• Filed: 04/30/2018
• Issued: 06/04/2019
• Est. Priority Date: 04/30/2018
• Status: Active Grant

• Current Assignee: Xerox Corporation (Xerox Holdings Corp.)
• Original Assignee: Xerox Corporation (Xerox Holdings Corp.)
• Inventors: Caporale, Christopher P., Rodriguez, Alberto
• Primary Examiner(s): Walsh, Daniel I
• Application Number:
  US15/967,255
• Time in Patent Office: 400 Days
• Field of Search: None
• CPC Class Codes: G06K 19/067 Record carriers with conductive marks, printed circuits or semiconductor circuit elements, e.g. credit or identity cards also with resonating or responding marks without active components
• CPC Class Codes: G06K 7/10316 using at least one antenna particularly designed for interrogating the wireless record carriers antennas in general H01Q1/22
• CPC Class Codes: G06K 7/10356 using a plurality of antennas, e.g. configurations including means to resolve interference between the plurality of antennas

Abstract

A radio frequency identification (RFID) technique is disclosed. The technique includes a printed RFID antenna array including at least three printed RFID antenna elements and an RFID reader device with at least one RFID reader antenna sized to transmit excitation energy to a number N>1 of printed RFID antenna elements of the printed RFID antenna array, where N is less than a total number of printed RFID antenna elements of the printed RFID antenna array. The RFID reader antenna is configured to receive a plurality of compound signals from respective subarrays consisting of N of the printed RFID antenna elements of the printed RFID antenna array. The RFID reader device also includes a demodulator, a decoder, and an output interface.

Claims

1. A radio frequency identification (RFID) system comprising:

a printed RFID tag comprising a printed RFID antenna array comprising at least three printed RFID antenna elements on a substrate of the RFID tag;

an electronic RFID reader device comprising at least one RFID reader antenna, at least one of the at least one RFID reader antenna being an RFID transmit and receive antenna configured to simultaneously transmit excitation energy to a number N>

1 of printed RFID antenna elements of the printed RFID antenna array, wherein N is less than a total number of printed RFID antenna elements of the printed RFID antenna array;

wherein the at least one RFID reader antenna is configured to receive a first compound signal from a first plurality consisting of N of the printed RFID antenna elements of the printed RFID antenna array when the printed RFID antenna array is positioned at a first reading location relative to the RFID transmit antenna in response to the excitation energy being transmitted at the first reading location, the first compound signal comprising interfering signals from the first plurality;

wherein the at least one RFID reader antenna is configured to receive a second compound signal from a second plurality consisting of N of the printed RFID antenna elements of the printed RFID antenna array when the printed RFID antenna array is positioned at a second reading location, different from the first reading location, relative to the RFID transmit antenna in response to the excitation energy being transmitted at the second reading location, the second compound signal comprising interfering signals from the second plurality, wherein the first plurality is different from the second plurality;

an electronic demodulator communicatively coupled to an output of the RFID reader antenna and configured to demodulate the first compound signal and the second compound signal and produce a first encoded signal and a second encoded signal; and

an electronic decoder communicatively coupled to an output of the electronic demodulator and configured to obtain read data from at least the first encoded signal and a second encoded signal, wherein the read data is representative of data stored by the printed RFID antenna array.

2. The system of claim 1,

wherein the at least one RFID reader antenna is configured to receive at least one additional compound signal from at least one additional plurality consisting of N of the printed RFID antenna elements of the printed RFID antenna array when the printed RFID antenna array is positioned at at least one additional reading location relative to the RFID transmit antenna;

wherein the electronic demodulator is configured to demodulate the at least one additional compound signal to produce at least one additional encoded signal; and

wherein the electronic decoder is configured to obtain the read data from the first encoded signal, the second encoded signal, and the at least one additional encoded signal.

3. The system of claim 1, wherein each of the at least three printed RFID antenna elements comprises a patch antenna element and a microstrip transmission line.

4. The system of claim 1, wherein the first encoded signal and the second encoded signal encode the read data in amplitude and phase information, and wherein the decoder determines the read data from the amplitude and phase information.

5. The system of claim 4, wherein the decoder comprises a Quadrature Amplitude Modulation (QAM) decoder.

6. The system of claim 5, wherein the QAM decoder comprises a 16QAM decoder.

7. The system of claim 1, wherein the substrate comprises paper, and wherein the printed RFID antenna array lacks a microchip.

8. The system of claim 1, wherein the printed RFID antenna array has an antenna element density of at least 50 printed RFID antenna elements per square inch.

9. The system of claim 1, wherein the first plurality consisting of N of the printed RFID antenna elements of the printed RFID antenna array share a common printed RFID antenna element with the second plurality consisting of N of the printed RFID antenna elements of the printed RFID antenna array.

10. The system of claim 1, wherein the at least three printed RFID antenna elements are arranged linearly on the substrate.

11. A method of reading a printed radio frequency identification (RFID) tag comprising a printed RFID antenna array comprising at least three printed RFID antenna elements on a substrate of the RFID tag, the method comprising:

providing at least one RFID reader antenna, at least one of the at least one RFID reader antenna being an RFID transmit and receive antenna configured to simultaneously transmit excitation energy to a number N>

1 of printed RFID antenna elements of the printed RFID antenna array, wherein N is less than a total number of printed RFID antenna elements of the printed RFID antenna array of the RFID tag;

receiving, by at least one RFID reader antenna, a first compound signal from a first plurality consisting of N of the printed RFID antenna elements of the printed RFID antenna array upon the printed RFID antenna array being positioned at a first reading location relative to the RFID transmit antenna in response to the excitation energy being transmitted at the first reading location, the first compound signal comprising interfering signals from the first plurality;

receiving, by the at least one RFID reader antenna, a second compound signal from a second plurality consisting of N of the printed RFID antenna elements of the printed RFID antenna array upon the printed RFID antenna array being positioned at a second reading location different from the first reading location, relative to the RFID transmit antenna, in response to the excitation energy being transmitted at the second reading location, the second compound signal comprising interfering signals from the second plurality, wherein the first plurality is different from the second plurality;

demodulating, by electronic demodulation circuitry, the first compound signal and the second compound signal to obtain a first encoded signal and a second encoded signal;

decoding, by electronic decoding circuitry, at least the first encoded signal and the second encoded signal to obtain read data representing data stored by the printed RFID antenna array.

12. The method of claim 11, further comprising:

receiving at least one additional compound signal from at least one additional plurality consisting of N of the printed RFID antenna elements of the printed RFID antenna array when the printed RFID antenna array is positioned at at least one additional reading location relative to the RFID transmit antenna; and

demodulating the at least one additional compound signal to produce at least one additional encoded signal;

wherein the decoding comprises decoding at least the first encoded signal, the second encoded signal, and the at least one additional encoded signal to obtain the read data.

13. The method of claim 11, wherein each of the at least three printed RFID antenna elements comprises a patch antenna element and a microstrip transmission line.

14. The method of claim 11, wherein the first encoded signal and the second encoded signal encode the read data in amplitude and phase information, and wherein the decoding comprises determines the read data from the amplitude and phase information.

15. The method of claim 14, wherein the decoder comprises a Quadrature Amplitude Modulation (QAM) decoder.

16. The method of claim 15, wherein the QAM decoder comprises a 16QAM decoder.

17. The method of claim 11, wherein the substrate comprises paper, and wherein the printed RFID antenna array lacks a microchip.

18. The method of claim 11, wherein the printed RFID antenna array has an antenna element density of at least 50 printed RFID antenna elements per square inch.

19. The method of claim 11, wherein the first plurality consisting of N of the printed RFID antenna elements of the printed RFID antenna array share a common printed RFID antenna element with the second plurality consisting of N of the printed RFID antenna elements of the printed RFID antenna array.

20. The method of claim 11, wherein the at least three printed RFID antenna elements are arranged linearly on the substrate.