Measuring device to measure the change in dielectric properties in an environment with variable dielectric properties

摘要

Measuring device (1) for measuring the change in dielectric properties in an environment, comprising - a capacitive measuring circuit provided with an electrical input and output connection (20; 21), wherein the measuring circuit comprises one or more coupled measuring capacitors (5; 50) that can be placed in the environment and where the capacitance of each of the measuring capacitors (5; 50) can be influenced by the dielectric properties of the environment, - an electric generator of alternating signal (2) is connected to a common ground to apply a first alternating electrical signal with a specific base frequency and a specific signal form to the input connection (20) of the measurement circuit where the input connection (20) and the output connection (21) is connected indirectly to the common ground connection, - a first signal processing means (7) to derive a second alternating electrical signal from the first s signal, where the second signal has the same base frequency and signal form as the first signal and moves 90 ° in phase with respect to the first signal, - means for determining the first quadrature (8) to calculate the component in phase I1C and the quadrature component Q1c of an output voltage Uc through the output connection (21) of the measurement circuit, wherein the first signal and the second signal function as reference signals, characterized in that the measuring device (1) it is provided with - means for determining the second quadrature (9) to calculate the phase component I1L and quadrature component Q1L of an input voltage UL through the input connection (20) of the measurement circuit, wherein the first signal and the second signal function as reference signals, - a calculation circuit (11) that is configured to calculate a ratio of the components in phase (I1L, I1C) and quadratic components ura (Q1L, Q1C) of the output voltage (UL) and the input voltage (UC).