Coaxial cavity for measuring level of liquid in a container
First Claim
1. A method for measuring the level of liquid in a container utilizing a coaxial cavity having an inner conductor coaxially suspended within a tubular outer conductor, the outer conductor having perforations to allow liquid surrounding the coaxial cavity to enter and terminate a portion of an annular region between the inner conductor and the outer conductor, the steps in the method comprising:
- partially submerging the coaxial cavity in the liquid in the container so that liquid enters and terminates a portion of the annular region between the inner conductor and the outer conductor, leaving a liquid-free portion in the annular region;
injecting a sinusoidal electric field into the liquid-free portion of the annular region;
varying the frequency of the electric signal while simultaneously monitoring the output power level in the liquid-free portion of the annular region for maximum and minimum output-power levels, the nth harmonic resonant frequencies of the liquid-free position of the coaxial cavity are equal to the frequencies of the electric signal at which maximum or minimum output power levels occur; and
determining the level of liquid in the container from the nth harmonic resonance frequencies and the dimensions of the container according to a predetermined scheme.
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Abstract
A method and means for measuring the level of a liquid in a container. A coaxial cavity having a perforated outer conductor is partially submerged in the liquid in the container wherein the liquid enters and terminates the annular region of the coaxial cavity. The fundamental resonant frequency of the portion of the coaxial cavity which does not contain liquid is determined experimentally and is used to calculate the length of the liquid-free portion of the coaxial cavity and thereby the level of liquid in the container.
24 Citations
15 Claims
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1. A method for measuring the level of liquid in a container utilizing a coaxial cavity having an inner conductor coaxially suspended within a tubular outer conductor, the outer conductor having perforations to allow liquid surrounding the coaxial cavity to enter and terminate a portion of an annular region between the inner conductor and the outer conductor, the steps in the method comprising:
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partially submerging the coaxial cavity in the liquid in the container so that liquid enters and terminates a portion of the annular region between the inner conductor and the outer conductor, leaving a liquid-free portion in the annular region; injecting a sinusoidal electric field into the liquid-free portion of the annular region; varying the frequency of the electric signal while simultaneously monitoring the output power level in the liquid-free portion of the annular region for maximum and minimum output-power levels, the nth harmonic resonant frequencies of the liquid-free position of the coaxial cavity are equal to the frequencies of the electric signal at which maximum or minimum output power levels occur; and determining the level of liquid in the container from the nth harmonic resonance frequencies and the dimensions of the container according to a predetermined scheme. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A device for measuring the level of liquid in a container comprising:
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a coaxial cavity hving an inner conductor coaxially suspended within a tubular outer conductor, the outer conductor having perforations to allow liquid surrounding the coaxial cavity to enter and terminate a portion of an annular region between the inner conductor and outer conductor; means for supporting the coaxial cavity within the container so that a bottom portion of the coaxial cavity is partially submerged in the liquid, leaving a liquid-free portion in the top of the annular region; means for generating a variable-frequency sinusoidal electric signal; means for injecting the electric signal into the liquid-free portion of the annular region connected to the means for generating and the coaxial cavity; and means for detecting an output power level in the liquid-free portion of the annular region connected to the coaxial cavity. - View Dependent Claims (9, 10, 11, 12, 13, 14, 15)
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Specification