Tank arrangement and method for estimating a signal propagation property of a substance composition in a predefined tank portion

A tank arrangement, comprising:

• a tank having a first tank portion defined by a first range of vertical distances from a bottom of the tank, and a second tank portion defined by a second range of vertical distances from the bottom of the tank, the second range of vertical distances only containing distances greater than all distances in the first range of vertical distances;
• an inlet for receiving a substance composition including at least a liquid first substance having a first density and a liquid second substance having a second density lower than the first density;
• at least a first radar gauging system arranged at the tank, the first radar gauging system comprising:
• a first transceiver for generating, transmitting and receiving electromagnetic signals;
• a first transmission line probe having a first probe end coupled to the first transceiver and an impedance discontinuity spaced apart along the first transmission line probe from the first probe end by a known first distance, the first transmission line probe being arranged inside the tank in such a way that a portion of the first transmission line probe extending from the first probe end to the impedance discontinuity is exclusively located in the first tank portion, the first transmission line probe being configured to guide an electromagnetic transmit signal provided by the first transceiver from the first probe end to the impedance discontinuity, and to return to the first transceiver an electromagnetic reflection signal resulting from reflection of the transmit signal at the impedance discontinuity;
• and
• first processing circuitry coupled to the first transceiver and configured to estimate, based on a timing relation between the transmit signal and the reflection signal and on the known first distance, a signal propagation property of the substance composition within a first volume surrounding the portion of the first transmission line probe.