USRE47622EActiveUtility

High-sensitivity subsurface sensing system

Assignee: THE ARIZONA BOARD OF REGENTS ON BEHALF OF UNIV OF ARIZONAPriority: Jul 11, 2008Filed: Sep 29, 2017Granted: Sep 24, 2019

Est. expiryJul 11, 2028(~2 yrs left)· nominal 20-yr term from priority

Inventors:Ben K. Sternberg Steven L. Dvorak Oleg Krichenko

H01Q 3/08G01V 3/104

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Claims

Abstract

A target is sensed by an antenna array having a transmitter antenna and a receiver antenna, both of which are caused to be electromagnetically coupled to the target. The antenna array is rotated, and as the array rotates, a change in at least one of the coupling between the transmitter antenna and the target and the coupling between the receiver antenna and the target is detected at multiple rotational orientations of the antenna array.

Claims

exact text as granted — not AI-modified

We claim:

1. A method for performing electromagnetic sensing of a target, the method comprising:
(a) providing an antenna array comprising a transmitter antenna and a receiver antenna;
(b) producing an electromagnetic field using the transmitter antenna to produce a coupling between the transmitter antenna and the target and between the receiver antenna and the target;
(c) rotating the antenna array;
(d) as the antenna array rotates, detecting a change in at least one of the coupling between the transmitter antenna and the target and the coupling between the receiver antenna and the target at multiple rotational orientations of the antenna array, using the receiver antenna; and
(e) sensing the target from the change detected at the multiple rotational orientations.

2. The method of claim 1 , wherein the sensing comprises frequency-domain electromagnetic sensing.

3. The method of claim 1 , wherein the transmitter antenna and the receiver antenna are oriented relative to each other to provide geometrical nulling.

4. The method of claim 3 , wherein the transmitter antenna and the receiver antenna are oriented orthogonally to each other.

5. The method of claim 1 , wherein the antenna array comprises an electronic nulling circuit connected between the transmitter antenna and the receiver antenna.

6. The method of claim 5 , wherein the electronic nulling circuit comprises a passive lossless ladder network.

7. The method of claim 1 , wherein step (α) comprises:
(i) providing a rotatable main beam; and
(ii) providing the antenna array in mechanical connection with the rotatable main beam such that the antenna array rotates with the rotatable main beam.

8. The method of claim 7 , wherein the antenna array is provided on an isolated beam which is mechanically connected to the rotatable main beam.

9. The method of claim 8 , wherein the isolated beam is mechanically connected to the rotatable main beam at only one point.

10. The method of claim 1 , wherein, during steps (c) and (d), the antenna array is oriented vertically relative to the earth&#39;s surface.

11. The method of claim 1 , wherein, during steps (c) and (d), the antenna array is oriented horizontally relative to the earth&#39;s surface.

12. A system for performing electromagnetic sensing of a target, the system comprising:
an antenna array comprising a transmitter antenna and a receiver antenna;
a motor for causing the antenna array to rotate; and
a controller, in electrical communication with the antenna array and the motor, for:
(i) controlling the transmitter antenna to produce an electromagnetic field to produce a coupling between the transmitter antenna and the target and between the receiver antenna and the target;
(ii) controlling the motor to rotate the antenna array;
(iii) as the antenna array rotates, detecting a change in at least one of the coupling between the transmitter antenna and the target and the coupling between the receiver antenna and the target at multiple rotational orientations of the antenna array, using the receiver antenna; and
(iv) sensing the target from the change detected at the multiple rotational orientations.

13. The system of claim 12 , wherein the system is configured to perform frequency-domain electromagnetic sensing of the target.

14. The system of claim 12 , wherein the transmitter antenna and the receiver antenna are oriented relative to each other to provide geometrical nulling.

15. The system of claim 14 , wherein the transmitter antenna and the receiver antenna are oriented orthogonally to each other.

16. The system of claim 12 , wherein the antenna array comprises an electronic nulling circuit connected between the transmitter antenna and the receiver antenna.

17. The system of claim 16 , wherein the electronic nulling circuit comprises a passive lossless ladder network.

18. The system of claim 12 , further comprising a rotatable main beam, wherein the antenna array is in mechanical connection with the rotatable main beam such that the antenna array rotates with the rotatable main beam.

19. The system of claim 18 , further comprising an isolated beam which is mechanically connected to the rotatable main beam, wherein the antenna array is provided on the isolated beam.

20. The system of claim 19 , wherein the isolated beam is mechanically connected to the rotatable main beam at only one point.

21. A method for performing electromagnetic sensing of a target, the method comprising:
(a) providing an antenna array comprising a transmitter antenna and a receiver antenna; (b) producing an electromagnetic field using the transmitter antenna to produce a coupling between the transmitter antenna and the target and between the receiver antenna and the target; (c) rotating the antenna array; (d) as the antenna array rotates, detecting a change in at least one of the coupling between the transmitter antenna and the target and the coupling between the receiver antenna and the target at a first rotational orientation of the antenna array and a second rotational orientation of the antenna array, using the receiver antenna; and (e) sensing the target from the change detected at the first rotational orientation and the second rotational orientation; wherein the first rotational orientation and the second rotational orientation are symmetric relative to a plane through which the target is sensed; and wherein the change detected at the first rotational orientation and the second rotational orientation comprises calculating a difference between a coupling at the first rotational orientation and a coupling at the second rotational orientation.

22. The method of claim 21, wherein the sensing comprises frequency-domain electromagnetic sensing.

23. The method of claim 21, wherein the transmitter antenna and the receiver antenna are oriented relative to each other to provide geometrical nulling.

24. The method of claim 23, wherein the transmitter antenna and the receiver antenna are oriented orthogonally to each other.

25. The method of claim 21, wherein the antenna array comprises an electronic nulling circuit connected between the transmitter antenna and the receiver antenna.

26. The method of claim 25, wherein the electronic nulling circuit comprises a passive lossless ladder network.

27. The method of claim 21, wherein step (a) comprises:
(i) providing a rotatable main beam; and (ii) providing the antenna array in mechanical connection with the rotatable main beam such that the antenna array rotates with the rotatable main beam.

28. The method of claim 27, wherein the antenna array is provided on an isolated beam which is mechanically connected to the rotatable main beam.

29. method of claim 28, wherein the isolated beam is mechanically connected to the rotatable main beam at only one point.

30. The method of claim 21, wherein, during steps (c) and (d), the antenna array is oriented vertically relative to the plane through which the target is sensed.

31. The method of claim 21, wherein, during steps (c) and (d), the antenna array is oriented horizontally relative to the plane through which the target is sensed.

32. The method of claim 21, wherein the first rotational orientation and the second rotational orientation are at angles plus or minus 45 degrees relative to the plane through which the target is sensed.

33. A system for performing electromagnetic sensing of a target, the system comprising:
an antenna array comprising a transmitter antenna and a receiver antenna; a motor for causing the antenna array to rotate; and a controller, in electrical communication with the antenna array and the motor, for:
(i) controlling the transmitter antenna to produce an electromagnetic field to produce a coupling between the transmitter antenna and the target and between the receiver antenna and the target;
(ii) controlling the motor to rotate the antenna array;
(iii) as the antenna array rotates, detecting a change in at least one of the coupling between the transmitter antenna and the target and the coupling between the receiver antenna and the target at a first rotational orientation of the antenna array and a second rotational orientation of the antenna array, using the receiver antenna; and
(iv) sensing the target from the change detected at the first rotational orientation and the second rotational orientation;
wherein the first rotational orientation and the second rotational orientation are symmetric relative to a plane through which the target is sensed; and wherein the change detected at the first rotational orientation and the second rotational orientation comprises calculating a difference between a coupling at the first rotational orientation and a coupling at the second rotational orientation.

34. The system of claim 33, wherein the system is configured to perform frequency-domain electromagnetic sensing of the target.

35. The system of claim 33, wherein the transmitter antenna and the receiver antenna are oriented relative to each other to provide geometrical nulling.

36. The system of claim 35, wherein the transmitter antenna and the receiver antenna are oriented orthogonally to each other.

37. The system of claim 33, wherein the antenna array comprises an electronic nulling circuit connected between the transmitter antenna and the receiver antenna.

38. The system of claim 37, wherein the electronic nulling circuit comprises a passive lossless ladder network.

39. The system of claim 33, further comprising a rotatable main beam, wherein the antenna array is in mechanical connection with the rotatable main beam such that the antenna array rotates with the rotatable main beam.

40. The system of claim 39, further comprising an isolated beam which is mechanically connected to the rotatable main beam, wherein the antenna array is provided on the isolated beam.

41. The system of claim 40, wherein the isolated beam is mechanically connected to the rotatable main beam at only one point.

42. The system of claim 33, wherein the first rotational orientation and the second rotational orientation are at angles plus or minus 45 degrees relative to the plane through which the target is sensed.

43. A method for performing electromagnetic sensing of a target, the method comprising:
(a) providing an antenna array comprising a transmitter antenna and a receiver antenna; (b) producing an electromagnetic field using the transmitter antenna to produce a coupling between the transmitter antenna and the target and between the receiver antenna and the target; (c) rotating the antenna array; (d) as the antenna array rotates, detecting a change in at least one of the coupling between the transmitter antenna and the target and the coupling between the receiver antenna and the target, at a first rotational orientation of the antenna array and a second rotational orientation of the antenna array, using the receiver antenna; and (e) sensing the target from the change detected at the first rotational orientation and the second rotational orientation; wherein the second rotational orientation is 180 degrees from the first rotational orientation; and wherein the change detected at the first rotational orientation and the second rotational orientation comprises calculating a difference between a coupling at the first rotational orientation and a coupling at the second rotational orientation.

44. The method of claim 43, wherein the sensing comprises frequency-domain electromagnetic sensing.

45. The method of claim 43, wherein the transmitter antenna and the receiver antenna are oriented relative to each other to provide geometrical nulling.

46. The method of claim 45, wherein the transmitter antenna and the receiver antenna are oriented orthogonally to each other.

47. The method of claim 43, wherein the antenna array comprises an electronic nulling circuit connected between the transmitter antenna and the receiver antenna.

48. The method of claim 47, wherein the electronic nulling circuit comprises a passive lossless ladder network.

49. The method of claim 43, wherein step (a) comprises:
(i) providing a rotatable main beam; and (ii) providing the antenna array in mechanical connection with the rotatable main beam such that the antenna array rotates with the rotatable main beam.

50. The method of claim 47, wherein the antenna array is provided on an isolated beam which is mechanically connected to the rotatable main beam.

51. The method of claim 50, wherein the isolated beam is mechanically connected to the rotatable main beam at only one point.

52. The method of claim 43, wherein, during steps (c) and (d), the antenna array is oriented vertically relative to the plane through which the target is sensed.

53. The method of claim 43, wherein, during steps (c) and (d), the antenna array is oriented horizontally relative to the plane through which the target is sensed.

54. A system for performing electromagnetic sensing of a target, the system comprising:
an antenna array comprising a transmitter antenna and a receiver antenna; a motor for causing the antenna array to rotate; and a controller, in electrical communication with the antenna array and the motor, for:
(i) controlling the transmitter antenna to produce an electromagnetic field to produce a coupling between the transmitter antenna and the target and between the receiver antenna and the target;
(ii) controlling the motor to rotate the antenna array;
(ii) as the antenna array rotates, detecting a change in at least one of the coupling between the transmitter antenna and the target and the coupling between the receiver antenna and the target, at a first rotational orientation and a second rotational orientation, using the receiver antenna; and
(iv) sensing the target from the change detected at the first rotational orientation and the second rotational orientation;
wherein the second rotational orientation is 180 degrees from the first rotational orientation; and wherein the change detected at the first rotational orientation and the second rotational orientation comprises calculating a difference between a coupling at the first rotational orientation and a coupling at the second rotational orientation.

55. The system of claim 54, wherein the system is configured to perform frequency-domain electromagnetic sensing of the target.

56. The system of claim 54, wherein the transmitter antenna and the receiver antenna are oriented relative to each other to provide geometrical nulling.

57. The system of claim 56, wherein the transmitter antenna and the receiver antenna are oriented orthogonally to each other.

58. The system of claim 54, wherein the antenna array comprises an electronic nulling circuit connected between the transmitter antenna and the receiver antenna.

59. The system of claim 58, wherein the electronic nulling circuit comprises a passive lossless ladder network.

60. The system of claim 54, further comprising a rotatable main beam, wherein the antenna array is in mechanical connection with the rotatable main beam such that the antenna array rotates with the rotatable main beam.

61. The system of claim 60, further comprising an isolated beam which is mechanically connected to the rotatable main beam, wherein the antenna array is provided on the isolated beam.

62. The system of claim 61, wherein the isolated beam is mechanically connected to the rotatable main beam at only one point.

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