METHODS AND SYSTEMS USING POLARIZATION MODULATED ELECTROMAGNETIC WAVES

• US 20090058657A1
• Filed: 08/30/2007
• Published: 03/05/2009
• Est. Priority Date: 08/30/2007
• Status: Active Grant

• Current Assignee: Round Rock Research LLC
• Original Assignee: Micron Technology, Inc.
• Inventors: Tuttle, John R.
• Granted Patent: US 8,400,269 B2
• Time in Patent Office: Days
• US Class Current: 340/572.700
• CPC Class Codes: G06K 19/0723 the record carrier comprising an arrangement for non-contact communication, e.g. wireless communication circuits on transponder cards, non-contact smart cards or RFIDs
• CPC Class Codes: G06K 19/07767 the first and second communication means being two different antennas types, e.g. dipole and coil type, or two antennas of the same kind but operating at different frequencies
• CPC Class Codes: G06K 7/0008 General problems related to the reading of electronic memory record carriers, independent of its reading method, e.g. power transfer
• CPC Class Codes: G06K 7/10316 using at least one antenna particularly designed for interrogating the wireless record carriers antennas in general H01Q1/22

Abstract

Methods and systems using polarization modulated electromagnetic waves. At least some of the illustrative embodiments are systems comprising a radio frequency identification (RFID) reader, and a RFID tag (the RFID tag communicatively coupled to the RFID reader),. The RFID tag is configured to transmit data to the RFID reader with data encoded in polarization of electromagnetic waves transmitted from the RFID tag.

Claims

1. A system comprising:

a radio frequency identification (RFID) reader; and

a RFID tag, the RFID tag communicatively coupled to the RFID reader;

wherein the RFID tag is configured to transmit data to the RFID reader, the data encoded in polarization of electromagnetic waves transmitted from the RFID tag.

2. The system according to claim 1 wherein the RFID tag is configured to encode data in polarization of electromagnetic waves backscattered electromagnetic signals.

3. The system according to claim 1 wherein the RFID tag further comprises:

a tag antenna system configured to transmit electromagnetic signals having a plurality of electric field polarizations;

a RFID circuit; and

a plurality of diodes coupled one each between the RFID circuit and a plurality of feed points of the tag antenna system;

wherein the RFID circuit is configured to encode the data, at least in part, by selectively forward biasing the plurality of diodes.

4. The system according to claim 3 wherein the tag antenna system further comprises at least one selected from the group consisting of:

a patch antenna having a plurality feed points;

a plurality of individual antennas, each antenna having a feed point.

5. The system according to claim 1 further comprising wherein the RFID reader is configured to send interrogating electromagnetic waves to the RFID tag in a plurality of electric field polarizations.

6. The system according to claim 1 further comprising wherein the RFID reader is configured to attempt to decode signals from a plurality of feed points, and select a signal based on check codes associated with each transmission from the RFID tag.

7. The system according to claim 1 further comprising an object to which the RFID tag is coupled.

8. The system according to claim 1 further comprising the reader associated with at least one selected from the group consisting of:

a doorway through which the RFID tags travel; and

a portable device configured to situate RFID reader proximate to the RFID tag.

9. The system according to claim 1 wherein the RFID reader is further configured to transmit data obtained from the RFID tag to a host computer, and wherein the host computer is configured to track the item in accordance with an inventory management process.

10. A radio frequency identification (RFID) tag comprising:

a tag antenna system configured to transmit electromagnetic waves having a plurality of distinct electric field polarizations; and

a RFID circuit coupled to the tag antenna system;

wherein the RFID tag is configured to transmit data in the form of electromagnetic waves using the tag antenna system, and wherein the data is encoded in differing electric field polarizations transmitted from the tag antenna system.

11. The RFID tag according to claim 10 further comprising:

a plurality of diodes coupled one each between a plurality of feed points of the tag antenna system and the RFID circuit;

wherein the RFID circuit is configured to transmit the data, at least in part, by selectively forward biasing the diodes.

12. The RFID tag according to claim 10 wherein when the RFID tag transmits the electromagnetic waves, the RFID tag transmits the electromagnetic waves in the form of backscattered electromagnetic waves.

13. The RFID tag according to claim 10 further comprising:

a power source coupled to the RFID circuit;

wherein the RFID tag is configured to transmit the data using power from the power source.

14. The RFID tag according to claim 10 wherein the RFID tag is configured to transmit the electromagnetic signals having a substantially constant transmitted power.

15. A method comprising:

sending an interrogating signal to a radio frequency identification (RFID) tag;

receiving a response from the RFID tag in the form an electromagnetic wave having polarization modulation.

16. The method according to claim 15 wherein sending further comprises sending the interrogating signal as a plurality of electromagnetic waves, each having different electric field polarization.

17. The method according to claim 15 wherein sending further comprises sending the interrogating signal during the receiving.

18. The method according to claim 15 wherein receiving the response further comprises:

receiving a plurality of electromagnetic waves each having a different electric filed polarization;

decoding data in the response using, at least in part, the plurality of electromagnetic waves considered together.

19. The method according to claim 18 wherein decoding further comprises:

assuming a relationship of data values to electric field polarizations;

decoding using the relationship; and

testing whether the relationship is correct.

20. The method according to claim 19 where testing further comprises determining whether check codes in the response are valid.

21. The method according to claim 15 further comprising:

transmitting the response to an electronic system; and

tracking the RFID tag in accordance with an inventory management process.

22. The method according to claim 15 wherein receiving further comprises at least one selected from the group consisting of:

receiving proximate to a portal through which the RFID tag travels;

receiving by a portable device configured to be positioned proximate to the RFID tag.

23. A system comprising:

a antenna system configured to receive electromagnetic waves having a plurality of distinct electric field polarizations; and

a radio frequency identification (RFID) reader coupled to the antenna system;

wherein the RFID reader is configured to receive data in the form of electromagnetic waves using the antenna system, and wherein the data is encoded in differing electric field polarizations transmitted from the tag antenna system.

24. The system according to claim 23 wherein when the RFID reader receives the electromagnetic waves, the RFID reader receives the electromagnetic waves in the form of backscattered electromagnetic waves.

25. The system according to claim 23 further comprising wherein the RFID reader is configured to transmit data to a RFID tag, the data encoded in polarization of electromagnetic waves transmitted from the antenna system.