Dielectric constant monitor
First Claim
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1. Apparatus for monitoring the dielectric constant of a material comprising:
- an amplifier having input and output ports,a transmission line connected at one end to the amplifier input and at the other end to the amplifier output forming a feedback loop, andoutput means connected to the loop;
whereinthe transmission line is embedded at least partly in the material when monitoring takes place,an electrical signal propagates one-way along the transmission line and through the amplifier in passing around the loop,the signal is inverted on each passage around the loop to sustain an electrical oscillation at a frequency determined in part by the propagation delay of the transmission line, andthe oscillation frequency is used by the output means to provide a measure of the dielectric constant of the material.
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Abstract
Monitoring of the average dielectric constant in an extended volume of a medium such as soil is achieved using an oscillator incorporating a transmission line to be embedded in the medium. The transmission line is connected as the feedback loop of an amplifier, for one-way propagation of an electrical signal with a delay determined largely by the dielectric properties of the medium, such as its moisture content. The oscillation frequency is indicative of the dielectric constant of the medium.
36 Citations
9 Claims
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1. Apparatus for monitoring the dielectric constant of a material comprising:
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an amplifier having input and output ports, a transmission line connected at one end to the amplifier input and at the other end to the amplifier output forming a feedback loop, and output means connected to the loop;
whereinthe transmission line is embedded at least partly in the material when monitoring takes place, an electrical signal propagates one-way along the transmission line and through the amplifier in passing around the loop, the signal is inverted on each passage around the loop to sustain an electrical oscillation at a frequency determined in part by the propagation delay of the transmission line, and the oscillation frequency is used by the output means to provide a measure of the dielectric constant of the material. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A method of monitoring the dielectric constant of a material comprising:
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embedding a transmission line in the material as part of an amplifier feedback loop, propagating an electrical signal one-way along the transmission line and through the amplifier, inverting the signal on each passage around the loop to create an electrical oscillation at a frequency determined in part by the propagation delay of the transmission line, and using the frequency to provide a measure of the dielectric constant of the material. - View Dependent Claims (9)
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Specification