A radar fill level measurement device for determining a fill level of a medium is provided, including a radar module to generate a transmission signal of at least 60 GHz; and an antenna coupled to the module and to transmit the signal to a surface of the medium and to receive a reflected signal, the module including a phase-locked loop including a push-push oscillator and a phase detector, the oscillator including a first and second outputs, a duplexer coupled between the push-push oscillator and the antenna, and a frequency multiplier coupled between the oscillator second output and the duplexer, the oscillator first output being directly wired to the phase detector input, the duplexer being coupled to the antenna, the phase detector including a reference input and a phase detector output coupled to an oscillator control input. A method for operating a radar fill level measurement device is also provided.