Patent US3725489A successfully refreshed from Google Patents.
Patent US3836841A successfully refreshed from Google Patents.
US3836841A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Electromagnetic device for determining the conductance of a nearby body by a single supercooled inductor coil
Assignee: University of California Berkeley
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Filing: 1973-01-15
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Granted: 1974-09-17
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Expires: 1993-01-15
Abstract
Abstract A towed electromagnetic prospecting device has a single inductor coil used for both transmitting and receiving secondary electromagnetic radiation from the ground which has been induced by the transmitted radiation. Such secondary fields from the ground are sensed as a change in the effective resistance of the superconducting inductive transmitter coil employed in the resonant resistance type bridge circuit.
Inventors
- 👤 H Morrison
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 11:17
CPC Classifications
G; G01; G01V; G01V3/00; G01V3/15; G01V3/165
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
114 words
An electromagnetic device for determining the conductance of a nearby body comprising: a magnetic dipole for radiating a time varying magnetic field towards said body; means in proximity to said magnetic dipole for supercooling said magnetic dipole to a temperature where said dipole is in a superconducting state; means for sensing an out-of-phase field with respect to said radiated field and which is produced by said body in response to said radiated field including resistance bridge means including said magnetic dipole as a portion thereof for sensing solely a change in effective resistance of said magnetic dipole caused by said out-of-phase field, said change in resistance being related to said conductance of said body.
Claim 2
Dependent Claim
114 words
An electromagnetic device for determining the conductance of a nearby body comprising: a magnetic dipole for radiating a time varying magnetic field towards said body; means in proximity to said magnetic dipole for supercooling said magnetic dipole to a temperature where said dipole is in a superconducting state; means for sensing an out-of-phase field with respect to said radiated field and which is produced by said body in response to said radiated field including resistance bridge means including said magnetic dipole as a portion thereof for sensing solely a change in effective resistance of said magnetic dipole caused by said out-of-phase field, said change in resistance being related to said conductance of said body.
Claim 3
Dependent Claim
31 words
A device as in claim 1 where said resistance bridge means includes a capacitor coupled to said magnetic dipole and means for exciting said dipole and capacitor into a resonance condition.
Claim 4
Dependent Claim
99 words
A device as in claim 1 where said magnetic dipole is an inductor and where said resistance bridge means is of the Wheatstone type having four arms and includes a capacitor in series with said inductor in one arm of said bridge, together with means for exciting said inductor and capacitor into a series resonance condition, said other three arms of said bridge including resistors for normally balancing said bridge with respect to the effective resistance of said series resonant L-C circuit, a change in the effective resistance caused by said out-of-phase field being sensed by said bridge circuit.
Claim 5
Dependent Claim
31 words
A device as in claim 2 where said exciting means includes a regenerative feedback loop coupled to said bridge means whereby the resonant frequency of said dipole and capacitor is tracked.
Claim 6
Dependent Claim
29 words
A device as in claim 1 together with means for towing said device above the surface of the earth said nearby body being a subsurface inhomogeneity of said earth.
Claim 7
Dependent Claim
24 words
A device as in claim 1 where said means for supercooling is a non-metallic cryostat capable of cooling said dipole to substantially 4.2* K.
Claim 8
Dependent Claim
169 words
An electromagnetic device for determining the conductance of a nearby body comprising: a magnetic dipole having a predetermined inductance for radiating a time varying magnetic field towards said body; means in proximity to said magnetic dipole for supercooling said magnetic dipole to a temperature where said dipole is in a superconducting state; means for sensing an out-of-phase field with respect to said radiated field and which is produced by said body in response to said radiated field including resistance bridge means including said magnetic dipole as a portion thereof for sensing a change in effective resistance of said magnetic dipole caused by said out-of-phase field, said change in resistance being related to said conductance of said body, said resistance bridge means including a capacitor coupled to said magnetic dipole and means for exciting said dipole and capacitor into a resonance condition including a regenerative feedback loop coupled to said bridge means for tracking the resonant frequency of said dipole and capacitor in response to mechanical forces changing said inductance.
Claim 9
Dependent Claim
169 words
An electromagnetic device for determining the conductance of a nearby body comprising: a magnetic dipole having a predetermined inductance for radiating a time varying magnetic field towards said body; means in proximity to said magnetic dipole for supercooling said magnetic dipole to a temperature where said dipole is in a superconducting state; means for sensing an out-of-phase field with respect to said radiated field and which is produced by said body in response to said radiated field including resistance bridge means including said magnetic dipole as a portion thereof for sensing a change in effective resistance of said magnetic dipole caused by said out-of-phase field, said change in resistance being related to said conductance of said body, said resistance bridge means including a capacitor coupled to said magnetic dipole and means for exciting said dipole and capacitor into a resonance condition including a regenerative feedback loop coupled to said bridge means for tracking the resonant frequency of said dipole and capacitor in response to mechanical forces changing said inductance.
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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) | 1977-09-16 | 1978-03-18 | 1978-09-17 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-09-16 | 1982-03-18 | 1982-09-17 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-09-16 | 1986-03-18 | 1986-09-17 | $7700.00 | Window Closed / Lapsed |