초록 ▼

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 o

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.

대표청구항 ▼

[ I claim:] [1.] An apparatus for detecting a proximity of a material, comprising:an oscillator which oscillates at a nominal frequency and produces an oscillator signal;an antenna coupled to the oscillator which is resonant at the nominal frequency of the oscillator and which has a characteristic i

[ I claim:] [1.] An apparatus for detecting a proximity of a material, comprising:an oscillator which oscillates at a nominal frequency and produces an oscillator signal;an antenna coupled to the oscillator which is resonant at the nominal frequency of the oscillator and which has a characteristic impedance which depends on materials in proximity to the antenna; anda detector coupled to the oscillator which detects changes in the oscillator signal as a result of changes in the characteristic impedance of the antenna caused by changes in materials in proximity to the antenna.