ELECTROMAGNETIC FIELD PERTURBATION SENSOR AND METHODS FOR MEASURING WATER CONTENT IN SHEETMAKING SYSTEMS

摘要

An apparatus for sensing three properties of materials: the conductivity or resistance, the dielectric constant, and the proximity of the material to the sensor portion of the apparatus. The apparatus includes a fixed impedance element coupled in serie s with the sensor portion of the apparatus between an input signal and ground. The sensor portion of the apparatus is an electrode configuration which includes at lea st two electrodes with a portion of the material residing between and in close proximity to the electrodes. The sensor exhibits a variable impedance resulting from changes in physical characteristics of the material. The fixed impedance element and the variabl e impedance of the sensor portion form a voltage divider network such that changes in impedance of the sensor portion results in changes in voltage on the output of the apparatus. The variable impedance of the sensor portion relates to changes i n property of the material being sensed which can then be related to changes in other physical characteristics of the material such as weight, chemical composition, and temperature.