Radar level gauge system and method for detecting submerged antenna condition

A method of measuring a distance to a surface of an aqueous substance using a radar level gauge system, comprising:

• generating, by a transceiver of the radar level gauge system, an electromagnetic transmit signal;
• providing the transmit signal to a microwave antenna of the radar level gauge system;
• radiating, by the microwave antenna, the transmit signal substantially vertically towards a surface of an aqueous substance;
• receiving, by the transceiver via the microwave antenna, a reflection signal resulting from reflection of the transmit signal;
• forming, by processing circuitry of the radar level gauge system coupled to the transceiver, an echo representation indicative of received energy as a function of distance, based on the reflection signal and a timing relation between the transmit signal and the reflection signal;
• determining, by the processing circuitry based on the echo representation, that the surface of the aqueous substance cannot be identified within a preconfigured maximum measurement distance from the microwave antenna;
• determining, by the processing circuitry based on the echo representation, that received energy for distances longer than the maximum measurement distance from microwave antenna is lower than a predefined threshold energy;
• and
• determining, by the processing circuitry, that the microwave antenna is submerged in the aqueous substance.