Embodiments relate to machines including a movable part. A transmitter circuit is configured to generate a radio signal and to transmit the radio signal towards the movable part via a transmit waveguide. A reflection of the radio signal from the movable part is received by a receive waveguide and guided through the receive waveguide to a receiver circuit, which is configured to determine a position and/or a speed of the movable part based on at least the received radio signal. The transmitter circuit and the receiver circuit may be comprised by a radar sensor.