PORTABLE RADIO FREQUENCY IDENTIFICATION (RFID) READER

• US 20110169613A1
• Filed: 01/13/2010
• Published: 07/14/2011
• Est. Priority Date: 01/13/2010
• Status: Active Grant

• Current Assignee: The Boeing Co.
• Original Assignee: The Boeing Co.
• Inventors: Shi, Fong, Voyce, Kenneth G., Chen, Ming
• Granted Patent: US 8,461,965 B2
• Time in Patent Office: Days
• US Class Current: 340/10.4
• CPC Class Codes: G01S 13/4445 amplitude comparisons monopulse, i.e. comparing the echo signals received by an antenna arrangement with overlapping squinted beams
• CPC Class Codes: G01S 13/4454 phase comparisons monopulse, i.e. comparing the echo signals received by an interferometric antenna arrangement
• CPC Class Codes: G01S 13/75 using transponders powered from received waves, e.g. using passive transponders , or using passive reflectors
• CPC Class Codes: G01S 3/043 Receivers

Abstract

A particular portable radio frequency identification (RFID) reader includes an active antenna array including a plurality of antenna elements to receive RFID signals from RFID devices. The antenna elements include control circuitry to control a beam pattern generated by the active antenna array. The portable RFID reader further includes sum circuitry and difference circuitry. The sum circuitry is operable to determine a sum signal by summing the RFID signals received by at least two of the plurality of antenna elements. The difference circuitry is operable to determine a difference signal between the RFID signals received by at least two of the plurality of antenna elements. The portable RFID reader also includes a controller to electronically steer the beam pattern and to determine a direction from the RFID reader to a particular RFID device.

Claims

1. A portable radio frequency identification (RFID) reader, comprising:

an active antenna array including a plurality of antenna elements to receive RFID signals from one or more RFID devices, wherein the plurality of antenna elements includes control circuitry to control a beam pattern generated by the active antenna array;

sum circuitry operable to determine a sum signal by summing the RFID signals received by at least two of the plurality of antenna elements;

difference circuitry operable to determine a difference signal between the RFID signals received by at least two of the plurality of antenna elements; and

a controller to electronically steer the beam pattern based on the sum signal and the difference signal using the control circuitry to determine a direction from the RFID reader to a particular RFID device of the one or more RFID devices.

2. The portable RFID reader of claim 1, wherein the RFID signals received have a characteristic wavelength, wherein the plurality of antenna elements are separated by a center-to-center distance of less than one half the characteristic wavelength.

3. The portable RFID reader of claim 2, wherein the center-to-center distance is less than one eighth of the characteristic wavelength.

4. The portable RFID reader of claim 1, further comprising a direction indicator to indicate the direction to the particular RFID device.

5. The portable RFID reader of claim 1, further comprising a portable housing, wherein the sum circuitry, the difference circuitry, the controller and a battery are at least partially housed within the portable housing.

6. The portable RFID reader of claim 1, wherein the controller determines the direction from the RFID reader to the particular RFID device based at least in part on a phase of the difference signal.

7. The portable RFID reader of claim 1, wherein the plurality of antenna elements are arranged in a linear configuration.

8. The portable RFID reader of claim 1, wherein the plurality of antenna elements are arranged in a nonlinear configuration.

9. The portable RFID reader of claim 1, wherein at least one of phase and amplitude of waveforms radiated by at least two of the antenna elements of the plurality of antenna elements are independently controllable.

10. The portable RFID reader of claim 1, further comprising an input device to receive at least one RFID device identifier indicating a target RFID device and a memory to store the at least one RFID device identifier, wherein the controller determines the direction to the particular RFID when an RFID device identifier of the particular RFID device is stored in the memory.

11. A portable radio frequency identification (RFID) reader, comprising:

an active antenna array including a plurality of antenna elements to receive RFID signals from one or more RFID devices, the received RFID signals having a characteristic wavelength, wherein the plurality of antenna elements include at least a first antenna element and a second antenna element, wherein the first antenna element and the second antenna element are spaced apart at a distance of less than one half of the characteristic wavelength; and

circuitry to electronically steer a beam pattern of the active antenna array based on the received RFID signals to determine a direction of a particular RFID device of the one or more RFID devices.

12. The portable RFID reader of claim 11, wherein the active antenna array includes at least one third antenna element between the first antenna element and the second antenna element.

13. The portable RFID reader of claim 11, further comprising sum circuitry coupled to the first antenna element and to the second antenna element to determine a sum signal by summing an RFID signal received by the first antenna element and the second antenna element.

14. The portable RFID reader of claim 11, further comprising difference circuitry coupled to the first antenna element and to the second antenna element to determine a difference signal between an RFID signal received by the first antenna element and the second antenna element.

15. A method of locating a targeted RFID device among a plurality of RFID devices, the method comprising:

sending at least one first RFID interrogation signal from an antenna array of a portable RFID reader, wherein the antenna array includes a plurality of antenna elements;

receiving a first response signal from a targeted RFID device proximate to the portable RFID reader by at least a first antenna element of the antenna array and by a second antenna element of the antenna array;

determining a sum signal by summing the first response signal received by the first antenna element and the first response signal received by the second antenna element;

determining a difference signal by determining a difference between the first response signal received by the first antenna element and the first response signal received by the second antenna element;

determining a direction from the RFID reader to the targeted RFID device based on the sum signal and the difference signal; and

activating an indicator of the portable RFID reader, wherein the indicator indicates the direction to the targeted RFID device.

16. The method of claim 15, further comprising electronically steering a second RFID interrogation signal from the portable RFID reader generally toward the targeted RFID device.

17. The method of claim 16, wherein the antenna array sends the first RFID interrogation signal by transmitting a first waveform having a phase and an amplitude from at least one antenna element of the plurality of antenna elements, and wherein electronically steered the second RFID interrogation signal includes sending a second waveform from the at least one antenna element, the second waveform having at least one of a modified phase and a modified amplitude relative to the first waveform.

18. The method of claim 16, further comprising:

receiving a second response signal from the targeted RFID device by at least the first antenna element of the antenna array and the second antenna element of the antenna array;

determining a second sum signal by summing the second response signal received by the first antenna element and the second response signal received by the second antenna element;

determining a second difference signal by determining a difference between the second response signal received by the first antenna element and the second response signal received by the second antenna element; and

determining a refined direction from the RFID reader to the targeted RFID device based on the second sum signal and the second difference signal.

19. The method of claim 15, further comprising:

receiving, in response to the first RFID interrogation signal, a plurality of response signals including the first response signal from a plurality of RFID devices proximate to the portable RFID reader including the targeted RFID device; and

filtering the plurality of response signals to identify the first response signal.

20. The method of claim 15, further comprising accessing a memory including data identifying the targeted RFID device, wherein the plurality of response signals are filtered based on the data.