A radar level gauge system for determining a topographic property of a product , the radar level gauge system comprising: a transceiver for generating, transmitting and receiving electromagnetic signals; a signal transfer element coupled to the transceiver and configured to emit an electromagnetic transmit signal from the transceiver in an emission direction ; a propagating member arranged and configured to propagate the transmit signal towards the surface of the product , and to propagate a reflection signal resulting from reflection of the transmit signal at the surface of the product back towards the transceiver , the propagating member being movably arranged in relation to the signal transfer element and configured to deflect the transmit signal from the signal transfer element to a plurality of different propagation directions, each propagation direction corresponding to a position of the propagating member in relation to the signal transfer element in a plane perpendicular to the emission direction ; an elastic system coupled to the signal transfer element and to the propagating member , and arranged to define at least one property of an oscillating relative movement between the propagating member and the signal transfer element in the plane perpendicular to the emission direction ; an actuator arranged to initiate the oscillating movement; and processing circuitry coupled to the transceiver and configured to determine the topographic property based on the transmit signal and the reflection signal, wherein the elastic system defines a first eigenfrequency of a first component of the oscillating movement and a second eigenfrequency, different from the first eigenfrequency, of a second component of the oscillating movement. a transceiver for generating, transmitting and receiving electromagnetic signals; a signal transfer element coupled to the transceiver and configured to emit an electromagnetic transmit signal from the transceiver in an emission direction ; a propagating member arranged and configured to propagate the transmit signal towards the surface of the product , and to propagate a reflection signal resulting from reflection of the transmit signal at the surface of the product back towards the transceiver , the propagating member being movably arranged in relation to the signal transfer element and configured to deflect the transmit signal from the signal transfer element to a plurality of different propagation directions, each propagation direction corresponding to a position of the propagating member in relation to the signal transfer element in a plane perpendicular to the emission direction ; an elastic system coupled to the signal transfer element and to the propagating member , and arranged to define at least one property of an oscillating relative movement between the propagating member and the signal transfer element in the plane perpendicular to the emission direction ; an actuator arranged to initiate the oscillating movement; and processing circuitry coupled to the transceiver and configured to determine the topographic property based on the transmit signal and the reflection signal, wherein the elastic system defines a first eigenfrequency of a first component of the oscillating movement and a second eigenfrequency, different from the first eigenfrequency, of a second component of the oscillating movement. <EOS>