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 disclosed. 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. 5 figs.
- Inventors:
- Issue Date:
- Research Org.:
- Univ. of California (United States)
- Sponsoring Org.:
- USDOE, Washington, DC (United States)
- OSTI Identifier:
- 675843
- Patent Number(s):
- 5832772
- Application Number:
- PAN: 8-379,044
- Assignee:
- Univ. of California, Oakland, CA (United States)
- DOE Contract Number:
- W-7405-ENG-48
- Resource Type:
- Patent
- Resource Relation:
- Other Information: PBD: 10 Nov 1998
- Country of Publication:
- United States
- Language:
- English
- Subject:
- 44 INSTRUMENTATION, INCLUDING NUCLEAR AND PARTICLE DETECTORS; LEVEL INDICATORS; DESIGN; USES; RF SYSTEMS; MEASURING METHODS; ANTENNAS
Citation Formats
McEwan, T E. Micropower RF material proximity sensor. United States: N. p., 1998.
Web.
McEwan, T E. Micropower RF material proximity sensor. United States.
McEwan, T E. Tue .
"Micropower RF material proximity sensor". United States.
@article{osti_675843,
title = {Micropower RF material proximity sensor},
author = {McEwan, T E},
abstractNote = {A level detector or proximity detector for materials capable of sensing through plastic container walls or encapsulating materials is disclosed. 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. 5 figs.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {1998},
month = {11}
}