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.