Quickly performed measuring method for ascertaining the concentration of the polar components in a material otherwise mainly non-polar
AssigneeBergwerksverband GmbH
InventorsHeinz Hoberg, Albert Klein
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AssigneeBergwerksverband GmbH
InventorsHeinz Hoberg, Albert Klein
Estimating the term…
Conventionally, the concentration of a polar component in an otherwise non-polar or negligibly polar material, e.g., water content in pourable coal, is ascertained by measuring the attenuation of electromagnetic waves transmitted through a layer-thin sample of the material, the waves having a frequency as near as possible to the maximum-dipole-relaxation-loss frequency f.sub.o, in order to maximize the power-loss effect of the transmitted waves, this being directly attributable to the polar component, and thereby serving to accentuate the effect of the polar component in the measurement signal. The present invention operates at lower frequencies, associated with low dipole-relaxation power-loss, and measures the time delay of the thusly transmitted waves, achieving an unexpected degree of temperature-independence in the measurement signal obtained, and simultaneously, because the power attenuation per unit thickness of the sample is so greatly decreased, making possible the use of samples of unprecedently great thickness, e.g., 1-meter-thick masonry walls whose water content is to be ascertained, compared to the 0.1-meter or 0.2-meter-thick samples to which such techniques have hitherto been limited.
In a method of ascertaining the concentration of a polar component of an otherwise non-polar or negligibly polar material, the step of using a microwave waveguide to transmit electromagnetic waves through a sample of the material and measuring the transmission delay of the thusly transmitted electromagnetic waves, the frequency of the electromagnetic waves not exceeding a predetermined upper limit, the upper limit being the lower one of two frequencies, one frequency being the frequency at which the dielectric constant of the polar component exceeds that of the remaining, non-polar or negligibly polar component of the material, the other frequency being the dipole-relaxation frequency f.sub.o of the polar component, wherein f.sub.o =1/2.pi..tau.,.tau. being the dipole-relaxation time-constant of the polar component.
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