Compact self-tuned electrical resonator for buried object locator applications
First Claim
1. An electrical resonator having a primary resonant frequency value fR, the resonator comprising:
- a conductor having an inductance value L;
a plurality of capacitors coupled to the conductor having a net capacitance value C disposed to provide a primary resonant frequency value fR<
500 kHz, wherein the capacitance value of at least one of the capacitors varies as a function of the voltage drop across it; and
a controller coupled to the at least one of the capacitors, including first circuit means for generating a control voltage VC corresponding to the difference between a first predetermined resonant frequency value fR1 and the primary resonant frequency value fR<
500 kHz, and second circuit means for applying the control voltage VC to the at least one of the capacitors, thereby obtaining the capacitance value C necessary to produce a primary resonant frequency value fR=fR1.
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Accused Products
Abstract
A self-tuning resonator for use in a transmitter apparatus for inducing alternating currents in a buried conductor. The resonator is dynamically tuned at frequencies below 500 kHz by exploiting the inherent voltage-variability of net capacitance in multilayer ceramic capacitors. The transmitter apparatus provides improved efficiency and induced output power suitable for use in a man-portable locator system, providing a very high magnetic field output from a physically small battery-powered resonator at frequencies under 500 kHz. The resonator exhibits a very low equivalent series resistance (ESR) and is adaptively retuned to a predetermined resonant frequency responsive to any changes in resonance arising from phenomena such as component heating, thereby supporting very high tank circuit currents from battery-powered source to produce very high magnetic flux output.
35 Citations
31 Claims
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1. An electrical resonator having a primary resonant frequency value fR, the resonator comprising:
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a conductor having an inductance value L;
a plurality of capacitors coupled to the conductor having a net capacitance value C disposed to provide a primary resonant frequency value fR<
500 kHz, wherein the capacitance value of at least one of the capacitors varies as a function of the voltage drop across it; and
a controller coupled to the at least one of the capacitors, including first circuit means for generating a control voltage VC corresponding to the difference between a first predetermined resonant frequency value fR1 and the primary resonant frequency value fR<
500 kHz, andsecond circuit means for applying the control voltage VC to the at least one of the capacitors, thereby obtaining the capacitance value C necessary to produce a primary resonant frequency value fR=fR1. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A transmitter apparatus for inducing alternating current in a buried conductor, comprising:
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an electrical power source for generating an alternating current; and
an electrical resonator coupled to the electrical power source and having a primary resonant frequency value fR, the electrical resonator including a conductor having an inductance value L;
a plurality of capacitors coupled to the conductor having a net capacitance value C disposed to provide a primary resonant frequency value fR<
500 kHz, wherein the capacitance value of at least one of the capacitors varies as a function of the voltage drop across it; and
a controller coupled to the at least one of the capacitors, including first circuit means for generating a control voltage VC corresponding to the difference between a first predetermined resonant frequency value fR1 and the primary resonant frequency value fR<
500 kHz, andsecond circuit means for applying the control voltage VC to the at least one of the capacitors, thereby obtaining the capacitance value C necessary to produce a primary resonant frequency value fR=fR1. - View Dependent Claims (13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23)
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24. A human-portable locator system for locating a buried conductor, comprising:
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a transmitter apparatus for inducing alternating current in the buried conductor, including an electrical power source for generating an alternating current; and
an electrical resonator coupled conductively to the electrical power source and having a resonant frequency value fR, including a conductor having an inductance value L;
a plurality of capacitors coupled to the conductor having a net capacitance value C disposed to provide a primary resonant frequency value fR<
500 kHz, wherein the capacitance value of at least one of the capacitors varies as a function of the voltage drop across it; and
a controller coupled to the at least one of the capacitors, including first circuit means for generating a control voltage VC corresponding to the difference between a first predetermined resonant frequency value fR1 and the primary resonant frequency value fR<
500 kHz, andsecond circuit means for applying the control voltage VC to the at least one of the capacitors, thereby obtaining the capacitance value C necessary to produce a primary resonant frequency value fR=fR1;
a sensor array for producing a plurality of sensor signals representing an electromagnetic field emission arising from the alternating current in the buried conductor;
a processor coupled to the sensor array for producing location data signals representing a location of the electromagnetic field emission corresponding to the sensor signals; and
a user interface coupled to the processor for reporting to a user a location for the buried conductor. - View Dependent Claims (25, 26, 27, 28, 29, 30, 31)
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Specification