Method and apparatus for identifying conductive objects by monitoring the true resistive component of impedance change in a coil system caused by the object

Patent · Thu Jan 01 00:00:00 EST 1981

OSTI ID:863867

Gregory, William D ^[1]; Capots, Larry H ^[2]; George, James P ^[3]; Janik, Richard ^[4]

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1. Vienna, VA
2. McLean, VA
3. Falls Church, VA
4. Arlington, VA

The type of conductor, its property, and if a metal, its type and cross-sectional area can be obtained from measurements made at different frequencies for the amount of unbalance created in a previously balanced stable coil detection system. The true resistive component is accurately measured and thus reflects only the voltage loss attributable to eddy currents caused by introduction of the test sample to the coil system. This voltage divided by corresponding applied frequency gives a curve which peaks at a frequency dependent upon type of conductor. For a metal this peak frequency is proportional to the samples resistivity divided by its cross-sectional area.

• Research Organization: Georgetown Univ., Washington, D.C. (USA)
• DOE Contract Number: AT(40-1)-3665
• Assignee: Georgetown University (Washington, DC)
• Patent Number(s): US 4263551
• OSTI ID: 863867
• Country of Publication: United States
• Language: English

Related Subjects

method
apparatus
identifying
conductive
monitoring
true
resistive
component
impedance
change
coil
caused
type
conductor
property
metal
cross-sectional
obtained
measurements
frequencies
amount
unbalance
created
previously
balanced
stable
detection
accurately
measured
reflects
voltage
loss
attributable
eddy
currents
introduction
sample
divided
corresponding
applied
frequency
curve
peaks
dependent
peak
proportional
samples
resistivity
eddy current
eddy currents
resistive component
accurately measure
accurately measured
impedance change
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