Apparatus and method for the detection and measurement of liquid water and ice layers on the surfaces of solid materials
First Claim
1. A measurement system, comprising:
- an antenna for placement proximate to a surface location subject to accumulation of ice and/or water layer and that exhibits a resonant frequency and an input admittance including a real term;
Maxwell bridge means coupled to the antenna for detecting said resonant frequency, said input admittance and said real term; and
frequency sweeping means for driving the antenna at a plurality of frequencies proximate in frequency to said resonant frequency wherein said resonant frequency, said input admittance and said real term may be determined.
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Abstract
An embodiment of the present invention is a roadway sensor for surface installation in a hole such that a thin ceramic contact sensor may be used to measure and cross-compare fundamental physical antenna parameters of the space immediately above a roadway or bridge surface. Measurements are combined by a microprocessor to discriminate between dry pavement, water (rain), snow and ice above the sensor head. Ambient surface temperature, water depth and ice/slush conditions are determined to estimate any hydroplaning hazard and ice/antifreeze/water mixtures. The sensor comprises an antenna that exhibits a resonant frequency and an input admittance including a real term; a Maxwell bridge coupled to the antenna for detecting the resonant frequency, input admittance and real term; and a frequency sweeping oscillator for driving the antenna at a plurality of frequencies proximate in frequency to the resonant frequency. A phase sensitive detector determines an attenuation rate and phase and thereby is able to extract a conductivity (σ) and a dielectric (ε) measurement. The microprocessor relates the conductivity and dielectric measurements to yield, for example, a pair of estimates for ice and water content and layer thickness.
78 Citations
14 Claims
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1. A measurement system, comprising:
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an antenna for placement proximate to a surface location subject to accumulation of ice and/or water layer and that exhibits a resonant frequency and an input admittance including a real term; Maxwell bridge means coupled to the antenna for detecting said resonant frequency, said input admittance and said real term; and frequency sweeping means for driving the antenna at a plurality of frequencies proximate in frequency to said resonant frequency wherein said resonant frequency, said input admittance and said real term may be determined. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
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Specification