Radar level gauge system and method with signal propagation path modeling

A radar level gauge system for determining the filling level of a product in a tank, comprising:

• a transceiver for generating, transmitting and receiving electromagnetic signals;
• a signal propagation device coupled to said transceiver and arranged to propagate an electromagnetic transmit signal towards a surface of the product and to return an electromagnetic reflection signal resulting from reflection of the electromagnetic transmit signal at the surface back towards said transceiver, wherein said signal propagation device is included in a signal propagation path for said transmit signal and said reflection signal, said signal propagation path comprising a first portion having known signal propagation properties, and a second portion, said first portion being located between said transceiver and said second portion;
• and
• processing circuitry coupled to said transceiver, said processing circuitry comprising:
• measurement relation determining circuitry for:
• determining, based on a timing relation between said transmit signal and said reflection signal, a first measurement relation between energy reflected by said impedance transitions along the first and second portions of said signal propagation path and travel time of said reflection signal along the first and second portions of said signal propagation path;
• and
• determining a second measurement relation between energy reflected by a first sub-set of said impedance transitions along the second portion of said signal propagation path and travel time of said reflection signal along the second portion of said signal propagation path based on said first measurement relation and said known signal propagation properties of the first portion of said signal propagation path, using a computational model of said signal propagation path;
• and
• filling level determining circuitry for determining said filling level based on said second measurement relation.