US3710243A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Microwave gage for monitoring thickness of a conductive workpiece, flaws therein or displacement relative thereto
Assignee: Lockheed Martin Corp
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Filing: 1971-08-18
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Granted: 1973-01-09
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Expires: 1991-08-18
Abstract
Abstract A microwave induction gage for inspecting a conductive workpiece such as conductive sheet material wherein microwave energy is fed to a gaging head having a conductive plate member coupling microwave energy onto the surface of the workpiece to be inspected. A waveguide window formed by the spacing between the conductive sheet material and a fin secured to said plate member and arranged transverse to the direction of energy propagation in the head area passes microwave energy, the amplitude of which varies as an exponential function of the spacing, whereby detection and measurement of the amplitude of the energy passing the window provides an indication of the magnitude of the spacing. The plate member is grooved to guide energy through the coupler head area. Also, a fin may be fitted longitudinally in the groove to aid mode stability. By employing two of the conductive plate members, one on either side of the workpiece so as to form a pair of spaced energy paths, the amplitude of the energy passing the windows may be detected and multiplied to provide an indication of the thickness of the workpiece with inherent compensation for lateral displacement.
Inventors
- 👤 P Keenan
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 05:48
CPC Classifications
G; G01; G01B; G01B15/00; G01B15/02; G01N; G01N22/00; G01N22/02
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
152 words
A microwave induction gage for inspecting a conductive workpiece comprising: a source of microwave energy; at least one conductive plate member arranged in a generally spaced parallel relation to said conductive workpiece and forming waveguide head means coupled to said source for propagating microwave energy along the surface of said workpiece, said conductive plate member having a fin secured thereto and extending in the direction of said workpiece and transverse to the direction of propagation of said microwave energy so as to form a waveguide window wherein the electric field component of the microwave energy coupled through said window is essentially short circuited by said fin and wherein the magnetic field component of said microwave energy coupled through said window varies as a function of a workpiece parameter to be detected; and means for detecting the amplitude of said microwave energy coupled through said window to indicate the magnitude of said parameter.
Claim 2
Dependent Claim
152 words
A microwave induction gage for inspecting a conductive workpiece comprising: a source of microwave energy; at least one conductive plate member arranged in a generally spaced parallel relation to said conductive workpiece and forming waveguide head means coupled to said source for propagating microwave energy along the surface of said workpiece, said conductive plate member having a fin secured thereto and extending in the direction of said workpiece and transverse to the direction of propagation of said microwave energy so as to form a waveguide window wherein the electric field component of the microwave energy coupled through said window is essentially short circuited by said fin and wherein the magnetic field component of said microwave energy coupled through said window varies as a function of a workpiece parameter to be detected; and means for detecting the amplitude of said microwave energy coupled through said window to indicate the magnitude of said parameter.
Claim 3
Dependent Claim
69 words
A device as defined in claim 1 having two conductive plate members arranged one on either side of said conductive sheet material and forming a pair of microwave energy paths, means for separately detecting the energy level passing the waveguide window in each of said energy paths, and means for multiplying the detected energy levels and providing an output signal proportional to the thickness of said conductive sheet material.
Claim 4
Dependent Claim
26 words
A device as defined in claim 1 wherein said conductive plate member includes a waveguide groove formed therein for directing the propagation of microwave energy therealong.
Claim 5
Dependent Claim
24 words
A device as defined in claim 3 including a fin in said waveguide groove and extending longitudinally thereof for mode stabilizing said microwave energy.
Claim 6
Dependent Claim
37 words
A device as defined in claim 1 including waveguide transition means interposed between said source of microwave energy and said plate member for assuring the efficient transfer of energy from said source to said waveguide head means.
Claim 7
Dependent Claim
87 words
A device as defined in claim 1 wherein said head means includes a pair of orthogonally disposed intersecting grooves defining two microwave energy paths coupled to said source for propagating microwave energy along the surface of said workpiece, intersecting fins carried in said grooves and forming waveguide windows for passing microwave energy, detector means for separately detecting the amplitude of said microwave energy passing each said window, and divider means for obtaining the ratio of the signals at the output of said detector means for flaw sensing.
Claim 8
Dependent Claim
43 words
A device as defined in claim 6 having two said head means, one on either side of the workpiece, divider means for each said head means, and means for multiplying the output of said divider means for sensing The thickness of said workpiece.
References Cited (Backward Citations)
US3628135A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-01-09 | 1976-07-10 | 1977-01-09 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-01-09 | 1980-07-10 | 1981-01-09 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-01-09 | 1984-07-10 | 1985-01-09 | $7700.00 | Window Closed / Lapsed |