An antenna apparatus for a fill level measurement device is provided, including an antenna configured to emit a measurement signal towards a filling material surface and to receive a reflected measurement signal reflected by the filling material surface; a motor configured to rotate the antenna about an axis of rotation; and an elongate focussing arrangement configured to focus the emitted measurement signal and/or the reflected measurement signal, wherein the antenna includes an array of a plurality of radiator elements configured to emit the measurement signal and/or to receive the reflected measurement signal.