Methods and systems of RFID tags using RFID circuits and antennas having unmatched frequency ranges

• US 7,777,630 B2
• Filed: 07/26/2007
• Issued: 08/17/2010
• Est. Priority Date: 07/26/2007
• Status: Expired due to Fees

• Current Assignee: Round Rock Research LLC
• Original Assignee: Round Rock Research LLC
• Inventors: Tuttle, John R.
• Primary Examiner(s): PHAM, TOAN NGOC
• Application Number:
  US11/828,813
• Publication Number:
  US 20090027168A1
• Time in Patent Office: 1,118 Days
• Field of Search: 340/572.7, 340/572.1, 340/572.8, 340/10.1, 340/10.2, 340/10.4, 343/860, 343/700.MS, 343/741, 343/745, 343/757, 343/853, 342/51
• US Class Current: 340/572.7
• CPC Class Codes: H04B 5/00 Near-field transmission systems, e.g. inductive or capacitive transmission systems
• CPC Class Codes: H04B 5/26 using coils
• CPC Class Codes: H04B 5/77 for interrogation

Abstract

Methods and systems of RFID tags using RFID circuits and antennas having unmatched frequency ranges. At least some of the illustrative embodiments are RFID tags comprising a RFID circuit configured to operate with an antenna having a first range of resonant frequencies, a tag antenna coupled to the RFID circuit (the tag antenna having a range of resonant frequencies different than the first range of resonant frequencies, the range of resonant frequencies of the tag antenna being a second range of resonant frequencies).

Claims

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

a RFID circuit configured to operate in a first range of resonant frequencies;

a tag antenna coupled to the RFID circuit, the tag antenna having a range of resonant frequencies different than the first range of resonant frequencies, the range of resonant frequencies of the tag antenna being a second range of resonant frequencies; and

a rectifier circuit coupled between the RFID circuit and the tag antenna, wherein the rectifier circuit is configured to be operable at the second range of resonant frequencies and enables the RFID circuit to operate in the second range of resonant frequencies.

2. The RFID tag according to claim 1 wherein the rectifier further comprises a diode.

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

a tag circuit configured to participate in a protocol for communications with a RFID reader;

a matching circuit coupled to the tag circuit, the matching circuit designed to operate with an antenna having the first range of resonant frequencies.

4. The RFID tag according to claim 1 wherein the first range of resonant frequencies is approximately 860 to 960 Mega Hertz, and the second range of frequencies has at least one frequency that is higher than the first range of frequencies.

5. The RFID tag according to claim 1 wherein the second range of frequencies is approximately 860 to 960 Mega Hertz, and the first range of frequencies has at least one frequency that is higher than the second range of frequencies.

6. A system comprising:

a radio frequency identification (RFID) reading system comprising;

a RFID reader; and

a reading antenna coupled to the RFID reader, the reading antenna configured to operate within a first band of frequencies;

a RFID tag comprising;

a RFID circuit configured to operate with RFID reading systems that operate in a second band of frequencies different than the first band of frequencies;

a tag antenna coupled to the RFID circuit, the tag antenna configured to operate in the first band of frequencies; and

a rectifier circuit coupled between the RFID circuit and the tag antenna, wherein the rectifier circuit is configured to operate at the first band of resonant frequencies and enables the RFID circuit to operate in the first band of resonant frequencies.

7. The system according to claim 6 wherein the RFID reader is configured to operate in the second band of frequencies.

8. The system according to claim 7 wherein RFID reading system further comprises a converter circuit coupled between the RFID reader and the reading antenna, wherein the converter circuit is configured to convert signals from the first band frequencies to the second band of frequencies.

9. The system according to claim 8 wherein the converter circuit is configured to convert signals using a heterodyning system.

10. The system according to claim 6 wherein the RFID circuit further comprises a tag circuit configured to participate in a protocol for communications with the RFID reader, and wherein at least one aspect of the protocol is present in both the first band and second band.

11. The system according to claim 10 wherein the RFID circuit further comprises a matching circuit coupled to the tag circuit, the matching circuit configured to operate with an antenna resonant in the first band of frequencies.

12. The system according to claim 6 wherein the first band of resonant frequencies is approximately 860 to 960 Mega Hertz, and the second band of frequencies is higher than the first band of frequencies.

13. The system according to claim 6 wherein the second band of frequencies is approximately 860 to 960 Mega Hertz, and the first band of frequencies is higher than the first band of frequencies.

14. A method to design a radio frequency identification (RFID) tag comprising:

selecting an RFID circuit designed to operate in a first band of frequencies;

selecting a tag antenna configured to operate in a second band of frequencies, the second band of frequencies different than the first band of frequencies; and

selecting a rectifier circuit to be coupled between the RFID circuit and the tag antenna, the rectifier circuit configured to be operable in the second band of frequencies and enabling the RFID circuit to operate in the second band of frequencies.

15. The method according to claim 14 further comprising, after selecting the RFID circuit, modifying a down-converter circuit of the RFID circuit to be operable in the second band of frequencies.

16. The method according to claim 14 wherein selecting the tag antenna further comprises designing a tag antenna to have a characteristic impedance to substantially match an impedance of a matching circuit portion of the RFID circuit, and further designing the antenna to be resonant in the second band of frequencies.

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

a means for participating in a protocol for communications with a RFID reader means;

a means for impedance matching, the means for impedance matching coupled to the means for participating;

a means for broadcasting electromagnetic waves coupled to the means for impedance matching, the means for broadcasting configured for operation in a first band of frequencies; and

a means for rectifying coupled between the mean for impedance matching and the means for broadcasting;

wherein the means for participating and the means for impedance matching are designed for use in systems operating in a second band of frequencies different than the first band of frequencies and further wherein the means for rectifying is configured to operate at the first band of resonant frequencies and enables the means for participating to be in the first band of frequencies.

18. The RFID tag according to claim 17 wherein the first band of frequencies is approximately 860 to 960 Mega Hertz, and the second band of frequencies is higher than the first range of frequencies.

19. The RFID tag according to claim 17 wherein the second band of frequencies is approximately 860 to 960 Mega Hertz, and the first band of frequencies is higher than the first range of frequencies.