Micropower RF material proximity sensor

Patent · Thu Jan 01 00:00:00 EST 1998

OSTI ID:871958

McEwan, Thomas E ^[1]

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1. Livermore, CA

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.

• Research Organization: Lawrence Livermore National Laboratory (LLNL), Livermore, CA (United States)
• DOE Contract Number: W-7405-ENG-48
• Assignee: Regents of University of California (Oakland, CA)
• Patent Number(s): US 5832772
• OSTI ID: 871958
• Country of Publication: United States
• Language: English

Related Subjects

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
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