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Patent US4290020A successfully refreshed from Google Patents.
US4290020A
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Method and apparatus for detecting subterranean anomalies by generating two parallel magnetic fields
Assignee: United States Department of the Navy
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Filing: 1979-04-20
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Granted: 1981-09-15
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Expires: 1999-04-20
Abstract
Abstract Improved method and apparatus for detecting anomalies beneath an area of earth's surface wherein an oscillator couples a current into two conductors laid parallel to each other to generate two magnetic fields in the earth beneath the area. The magnetic field is measured along a line midway between the two horizontal conductors to detect for an increase in the measured field which is an indication of the presence of an anomaly.
Inventors
- 👤 Peder M. Hansen
- 👤 John G. Hoffman
- 👤 Elwin W. Seeley
- 👤 Wesley A. Andrew
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 23:45
CPC Classifications
G; G01; G01V; G01V3/00; G01V3/08
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
101 words
In the method of detecting subterranean anomalies wherein two parallel magnetic fields are generated and the strength of the field resulting from their intersection along a centerline midway between the fields is measured, the improvement comprising the step of: generating the fields by means of a pair of substantially parallel conductors placed on the earth in the vicinity of a suspected anomaly through which conductors uniform, in-phase currents are caused to flow by connecting each conductor at one end to the same terminal of a source of alternating current, and terminating each conductor at its other end in its characteristic impedance.
Claim 2
Dependent Claim
101 words
In the method of detecting subterranean anomalies wherein two parallel magnetic fields are generated and the strength of the field resulting from their intersection along a centerline midway between the fields is measured, the improvement comprising the step of: generating the fields by means of a pair of substantially parallel conductors placed on the earth in the vicinity of a suspected anomaly through which conductors uniform, in-phase currents are caused to flow by connecting each conductor at one end to the same terminal of a source of alternating current, and terminating each conductor at its other end in its characteristic impedance.
Claim 3
Dependent Claim
106 words
In an apparatus for detecting subterranean anomalies wherein two parallel magnetic fields are generated and the strength of the field resulting from their intersection along a centerline midway between the fields is measured, the improvement comprising: a source of alternating current having one grounded terminal and another, nongrounded terminal; and a pair of substantially parallel conductors placed on the earth in the vicinity of a suspected anomaly, each conductor being connected at one end to the nongrounded terminal of the current source and at the other end in its characteristic impedance; whereby, uniform in-phase currents flow in the conductors generating a magnetic field around each conductor.
Claim 4
Dependent Claim
106 words
In an apparatus for detecting subterranean anomalies wherein two parallel magnetic fields are generated and the strength of the field resulting from their intersection along a centerline midway between the fields is measured, the improvement comprising: a source of alternating current having one grounded terminal and another, nongrounded terminal; and a pair of substantially parallel conductors placed on the earth in the vicinity of a suspected anomaly, each conductor being connected at one end to the nongrounded terminal of the current source and at the other end in its characteristic impedance; whereby, uniform in-phase currents flow in the conductors generating a magnetic field around each conductor.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1984-09-14 | 1985-03-16 | 1985-09-15 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1988-09-14 | 1989-03-16 | 1989-09-15 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1992-09-14 | 1993-03-16 | 1993-09-15 | $7700.00 | Window Closed / Lapsed |