Frequency detection system comprising circuitry for adjusting the resonance frequency of a high temperature superconductor self-resonant coil

• US 7,332,910 B2
• Filed: 11/22/2004
• Issued: 02/19/2008
• Est. Priority Date: 11/24/2003
• Status: Expired due to Fees

• Current Assignee: Penn State Research Foundation
• Original Assignee: E. I. du Pont de Nemours and Company (Corteva, Inc.), Penn State Research Foundation
• Inventors: Schiano, Jeffrey L., Wilker, Charles, Laubacher, Daniel B.
• Primary Examiner(s): SHRIVASTAV, BRIJ B
• Application Number:
  US10/994,753
• Publication Number:
  US 20060012371A1
• Time in Patent Office: 1,184 Days
• Field of Search: 324/322, 324/318, 324/319, 324/307, 324/309, 324/300, 600/410, 600/422
• US Class Current: 324/318
• CPC Class Codes: G01N 24/084 Detection of potentially hazardous samples, e.g. toxic samples, explosives, drugs, firearms, weapons
• CPC Class Codes: G01R 33/035 using superconductive devices
• CPC Class Codes: G01R 33/34023 Superconducting RF coils
• CPC Class Codes: G01R 33/3628 Tuning/matching of the transmit/receive coil
• CPC Class Codes: G01R 33/441 Nuclear Quadrupole Resonance [NQR] Spectroscopy and Imaging

Abstract

The use of a circuit to adjust the resonance frequency of a high temperature superconductor self-resonant transmit, receive, or transmit and receive coil results in improved performance. The circuit is useful in a frequency detection system, especially in a nuclear quadrupole resonance detection system.

Claims

1. A circuit to adjust the power dependent resonance frequency of a high temperature superconductor self-resonant transmit or transmit and receive coil, wherein the circuit is comprised of

a single loop or coil to inductively couple the circuit to the high temperature superconductor self-resonant coil,

a reactance in series with the single loop or coil, and

means operative while the coil is transmitting for connecting the reactance to, and disconnecting the reactance from, the single loop or coil, the connection and disconnection of the reactance serving to adjust the power dependent resonance frequency of the coil.

2. The circuit of claim 1 wherein the circuit is comprised of a single loop, and the high temperature superconductor self-resonant transmit or transmit and receive coil is a planar coil.

3. The circuit of claim 1 wherein the circuit is comprised of a single loop, and the high temperature superconductor self-resonant transmit or transmit and receive coil is comprised of two coupled high temperature superconductor planar coils.

4. The circuit of any of claims 1-3 wherein the reactance can be varied.

5. A circuit to adjust the resonance frequency of a high temperature superconductor self-resonant coil, comprising:

a single loop or coil to inductively couple the circuit to the high temperature superconductor self-resonant coil;

a variable reactance in series with the single loop or coil, wherein the reactance comprises two or more capacitors in parallel; and

means for connecting the reactance to, and disconnecting the reactance from, the single loop or coil, the means for connecting the reactance to, and disconnecting the reactance from, the single loop or coil enables each of the capacitors to be individually connected to, and disconnected from, the single loop or coil.

6. The circuit of claim 5 wherein the means for connecting the reactance to, and disconnecting the reactance from, the single loop or coil comprises one mechanical or electrical switch for each of the capacitors.

7. A circuit to adjust the resonance frequency of a high temperature superconductor self-resonant coil, comprising:

a single loop or coil to inductively couple the circuit to the high temperature superconductor self-resonant coil;

a variable reactance in series with the single loop or coil, wherein the reactance comprises two or more inductors in series; and

means for connecting the reactance to, and disconnecting the reactance from, the single loop or coil, the means for connecting the reactance to, and disconnecting the reactance from, the single loop or coil enables each of the inductors to be individually connected to, and disconnected from, the single loop or coil.

8. The circuit of claim 7 wherein the means for connecting the reactance to, and disconnecting the reactance from, the single loop or coil comprises one mechanical or electrical switch for each of the inductors.

9. A frequency detection system, comprising:

a high temperature superconductor self-resonant transmit and receive coil; and

a circuit to adjust the power dependent resonance frequency of the high temperature superconductor self-resonant transmit and receive coil;

wherein the circuit is comprised of a single loop or coil to inductively couple the circuit to the high temperature superconductor self-resonant transmit and receive coil,

a variable reactance in series with the single loop or coil, and

means operative while the coil is transmitting for connecting the reactance to, and disconnecting the reactance from, the single loop or coil, the connection and disconnection of the reactance serving to adjust the power dependent resonance frequency of the coil.

10. The frequency detection system of claim 9 wherein the circuit is comprised of a single loop, and the high temperature superconductor self-resonant transmit and receive coil is a planar coil.

11. The frequency detection system of claim 9 wherein the circuit is comprised of a single loop, and the high temperature superconductor self-resonant transmit and receive coil is comprised of two coupled high temperature superconductor planar coils.

12. The frequency detection system of any of claims 9-11 wherein the reactance can be varied.

13. The frequency detection system of any of claims 9-11 which comprises a nuclear quadrupole resonance detection system.

14. The frequency detection system of claim 13 wherein the nuclear quadrupole resonance detection system detects explosives, drugs or other contraband.

15. A frequency detection system comprising:

a high temperature superconductor self-resonant transmit and receive coil;

a circuit to adjust the resonance frequency of the high temperature superconductor self-resonant transmit and receive coil, wherein the circuit comprises a single loop or coil to inductively couple the circuit to the high temperature superconductor self-resonant transmit and receive coil;

a variable reactance in series with the single loop or coil, wherein the reactance is comprised of two or more capacitors in parallel, and

means for connecting the reactance to, and disconnecting the reactance from, the single loop or coil, the means enabling each of the capacitors to be individually connected to, and disconnected from, the single loop or coil.

16. The frequency detection system of claim 15 wherein the means for connecting the reactance to, and disconnecting the reactance from, the single loop or coil comprises one mechanical or electrical switch for each of the capacitors.

17. A frequency detection system comprising:

a high temperature superconductor self-resonant transmit and receive coil;

a circuit to adjust the resonance frequency of the high temperature superconductor self-resonant transmit and receive coil, wherein the circuit comprises a single loop or coil to inductively couple the circuit to the high temperature superconductor self-resonant transmit and receive coil;

a variable reactance in series with the single loop or coil, wherein the reactance is comprised of two or more inductors in series, and

means for connecting the reactance to, and disconnecting the reactance from, the single loop or coil, the means enabling each of the inductors to be individually connected to, and disconnected from, the single loop or coil.

18. The frequency detection system of claim 17 wherein the means for connecting the reactance to, and disconnecting the reactance from, the single loop or coil comprises one mechanical or electrical switch for each of the inductors.

19. A frequency detection system, comprising:

a high temperature superconductor self-resonant transmit coil; and

a circuit to adjust the power dependent resonance frequency of the high temperature superconductor self-resonant transmit coil;

wherein the circuit is comprised of a single loop or coil to inductively couple the circuit to the high temperature superconductor self-resonant transmit coil,

a reactance in series with the single loop or coil, and

means operative while the coil is transmitting for connecting the reactance to, and disconnecting the reactance from, the single loop or coil, the connection and disconnection of the reactance serving to adjust the power dependent resonance frequency of the coil.

20. The frequency detection system of claim 19 wherein the single loop or coil is a single loop, and the high temperature superconductor self-resonant transmit coil is a planar coil.

21. The frequency detection system of claim 19 wherein the single loop or coil is a single loop, and the high temperature superconductor self-resonant transmit coil is comprised of two coupled high temperature superconductor planar coils.

22. The frequency detection system of any of claims 19-21 wherein the reactance can be varied.

23. The frequency detection system of any of claims 19-21 which comprises a nuclear quadrupole resonance detection system.

24. The frequency detection system of claim 23 wherein the nuclear quadrupole resonance detection system detects explosives, drugs or other contraband.

25. A frequency detection system comprising:

a high temperature superconductor self-resonant transmit coil;

a circuit to adjust the resonance frequency of the high temperature superconductor self-resonant transmit coil, wherein the circuit comprises a single loop or coil to inductively couple the circuit to the high temperature superconductor self-resonant transmit coil;

a variable reactance in series with the single loop or coil, wherein the reactance is comprised of two or more capacitors in parallel, and

means for connecting the reactance to, and disconnecting the reactance from, the single loop or coil, the means enabling each of the capacitors to be individually connected to, and disconnected from, the single loop or coil.

26. The frequency detection system of claim 25 wherein the means for connecting the reactance to, and disconnecting the reactance from, the single loop or coil comprises one mechanical or electrical switch for each of the capacitors.

27. A frequency detection system comprising:

a high temperature superconductor self-resonant transmit coil;

a circuit to adjust the resonance frequency of the high temperature superconductor self-resonant transmit coil, wherein the circuit comprises a single loop or coil to inductively couple the circuit to the high temperature superconductor self-resonant transmit coil;

a variable reactance in series with the single loop or coil, wherein the reactance is comprised of two or more inductors in series, and

means for connecting the reactance to, and disconnecting the reactance from, the single loop or coil, the means enabling each of the two or more inductors to be individually connected to, and disconnected from, the single loop or coil.

28. The frequency detection system of claim 27 wherein the means for connecting the reactance to, and disconnecting the reactance from, the single loop or coil comprises one mechanical or electrical switch for each of the inductors.

29. A frequency detection system comprising:

a high temperature superconductor self-resonant receive coil;

a circuit to adjust the resonance frequency of the high temperature superconductor self-resonant receive coil, wherein the circuit comprises a single loop or coil to inductively couple the circuit to the high temperature superconductor self-resonant transmit coil;

a variable reactance in series with the single loop or coil, wherein the reactance is comprised of two or more capacitors in parallel, and

means for connecting the reactance to, and disconnecting the reactance from, the single loop or coil, the means enabling each of the capacitors to be individually connected to, and disconnected from, the single loop or coil.

30. The frequency detection system of claim 29 wherein the means for connecting the reactance to, and disconnecting the reactance from, the single loop or coil comprises one mechanical or electrical switch for each of the capacitor.

33. The frequency detection system of any of claims 29-31 which comprises a nuclear quadrupole resonance detection system.

34. The frequency detection system of claim 33 wherein the nuclear quadrupole resonance detection system detects explosives, drugs or other contraband.

31. A frequency detection system comprising:

a high temperature superconductor self-resonant receive coil;

a circuit to adjust the resonance frequency of the high temperature superconductor self-resonant receive coil, wherein the circuit comprises a single loop or coil to inductively couple the circuit to the high temperature superconductor self-resonant transmit coil;

a variable reactance in series with the single loop or coil, wherein the reactance is comprised of two or more inductors in series, and

means for connecting the reactance to, and disconnecting the reactance from, the single loop or coil, the means enabling each of the inductors to be individually connected to, and disconnected from, the single loop or coil.

32. The frequency detection system of claim 31 wherein the means for connecting the reactance to, and disconnecting the reactance from, the single loop or coil comprises one mechanical or electrical switch for each of the inductors.