| 摘要 |
The present invention relates a measuring device (1) for measuring change in the dielectric properties of an environment, comprising • a capacitive measuring circuit provided with an input and output electrical, connection, wherein the measuring circuit comprises one or more coupled measuring capacitors (4, 5, 6) which are placeable in the environment and wherein the capacitance of the measuring capacitor (5) can be influenced by the dielectric properties of the environment, • an electric alternating signal generator (2) for applying a first electric alternating signal with a specific base frequency and a specific signal shape between the input and output connection of the measuring circuit, • a first signal processing means (7) for deriving a second electric alternating signal from the first signal, wherein the second signal has the same base frequency and signal shape as the first signal and is shifted 90° in phase relative to the first signal, • a first quadrature determining means (8) for calculating the inphase component I1 c and quadrature component Q1 c of an output voltage U c across the output connection of the measuring circuit, wherein the first signal and second signal function as reference signals, • a second quadrature determining means (9) for calculating the inphase component I1 L and quadrature component Q1 L of an output voltage U L across the input connection of the measuring circuit, wherein the first signal and second signal function as reference signals, • a calculation circuit (11) configured to calculate a ratio of the inphase components (I1 c, I1 L) and the quadrature components (Q1 c, Q1 L). |
