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Title: Micropower RF material proximity sensor

Abstract

A level detector or proximity detector for materials capable of sensing through plastic container walls or encapsulating materials is of the sensor. Thus, it can be used in corrosive environments, as well as in a wide variety of applications. An antenna has a characteristic impedance which depends on the materials in proximity to the antenna. An RF oscillator, which includes the antenna and is based on a single transistor in a Colpitt's configuration, produces an oscillating signal. A detector is coupled to the oscillator which signals changes in the oscillating signal caused by changes in the materials in proximity to the antenna. The oscillator is turned on and off at a pulse repetition frequency with a low duty cycle to conserve power. The antenna consists of a straight monopole about one-quarter wavelength long at the nominal frequency of the oscillator. The antenna may be horizontally disposed on a container and very accurately detects the fill level within the container as the material inside the container reaches the level of the antenna.

Inventors:
 [1]
  1. Livermore, CA
Issue Date:
Research Org.:
Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
OSTI Identifier:
871958
Patent Number(s):
5832772
Assignee:
Regents of University of California (Oakland, CA)
Patent Classifications (CPCs):
G - PHYSICS G01 - MEASURING G01F - MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL
DOE Contract Number:  
W-7405-ENG-48
Resource Type:
Patent
Country of Publication:
United States
Language:
English
Subject:
micropower; rf; material; proximity; sensor; level; detector; materials; capable; sensing; plastic; container; walls; encapsulating; corrosive; environments; wide; variety; applications; antenna; characteristic; impedance; depends; oscillator; based; single; transistor; colpitt; configuration; produces; oscillating; signal; coupled; signals; changes; caused; pulse; repetition; frequency; duty; cycle; conserve; power; consists; straight; monopole; one-quarter; wavelength; nominal; horizontally; disposed; accurately; detects; fill; inside; reaches; material inside; proximity sensor; materials capable; corrosive environment; pulse repetition; duty cycle; wide variety; repetition frequency; characteristic impedance; level detector; container wall; horizontally disposed; quarter wavelength; proximity detector; micropower rf; signal caused; one-quarter wavelength; corrosive environments; container walls; encapsulating material; quarter wave; accurately detect; /73/340/

Citation Formats

McEwan, Thomas E. Micropower RF material proximity sensor. United States: N. p., 1998. Web.
McEwan, Thomas E. Micropower RF material proximity sensor. United States.
McEwan, Thomas E. Thu . "Micropower RF material proximity sensor". United States. https://www.osti.gov/servlets/purl/871958.
@article{osti_871958,
title = {Micropower RF material proximity sensor},
author = {McEwan, Thomas E},
abstractNote = {A level detector or proximity detector for materials capable of sensing through plastic container walls or encapsulating materials is of the sensor. Thus, it can be used in corrosive environments, as well as in a wide variety of applications. An antenna has a characteristic impedance which depends on the materials in proximity to the antenna. An RF oscillator, which includes the antenna and is based on a single transistor in a Colpitt's configuration, produces an oscillating signal. A detector is coupled to the oscillator which signals changes in the oscillating signal caused by changes in the materials in proximity to the antenna. The oscillator is turned on and off at a pulse repetition frequency with a low duty cycle to conserve power. The antenna consists of a straight monopole about one-quarter wavelength long at the nominal frequency of the oscillator. The antenna may be horizontally disposed on a container and very accurately detects the fill level within the container as the material inside the container reaches the level of the antenna.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {1998},
month = {1}
}

Patent:

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