Tdr measuring apparatus for determining the dielectric constant

Abstract

The invention relates to a TDR measuring apparatus for determining at least the dielectric constant and material properties possibly derived therefrom, in particular the moisture and / or the conductivity, of a medium (2) flowing through a pipeline (1), having signal generation electronics (3) which generate TDR measurement signals, transmitting and / or receiving electronics (4) which emit and / or receive the TDR measurement signals, a coupling-in / coupling-out apparatus (5) which couples the TDR measurement signals into an electrical conductive measuring probe (6) of a predefined length (L) and couples said signals out of the measuring probe (6), and control / evaluation electronics (7) which use the propagation time of the TDR measurement signals on the measuring probe (6) to determine at leastthe dielectric constant and material properties possibly derived therefrom, in particular the moisture and / or the conductivity, wherein the measuring probe(6) is arranged in an electrically insulatedmanner outside the interior (8) of the pipeline (1) through which the medium (2) flows, or wherein the measuring probe (6) is placed in the pipeline (1) in such a manner that the outer surface of themeasuring probe (6) facing the medium (2) terminates in a manner flush with the inner surface of the pipeline (1) facing the medium (2), and is configured such that the propagation time and / or the amplitude of the measurement signals on the measuring probe (6) is / are dependent on the dielectric constant of the medium (2) flowing through the pipeline (1).

Description

technical field [0001] The invention relates to a TDR measuring device for determining the permittivity of a medium passing through a pipeline and / or material properties derived from said permittivity, in particular water content and / or electrical conductivity. It goes without saying that the conduit may be any wire suitable for carrying the medium. Therefore, it can be a closed line or a channel-shaped line. Background technique [0002] The dielectric TDR measurement principle has been used in many industrial applications to determine the water content of media. The dielectric constant (DC) of the material is measured via a radio frequency electromagnetic field which penetrates the material to be measured. The dielectric constant of water has a value of 80 at 20° C., and is therefore very different from that of solids, which have a DC value of 3 to 30, depending on the material. With this strong dielectric contrast, the dielectric constant can thus be used as a paramete...

AI Technical Summary

Problems solved by technology

[0008] The challenge of TDR measurement is that the propagation time of the electromagnetic wave on the probe is very short

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