Phase noise analysis in FMCW radar systems

Phase noise in radar transmitters is known to raise the noise floor around large targets, making impossible the detection & tracking of small targets nearby. This paper presents phase-noise modelling techniques, with a focus on homodyne FMCW radars, to accurately predict the level of phase noise expected in the radar display. Phase noise models of the sub-systems inside a typical radar are presented. We also discuss the cancellation of phase noise in coherent radar systems for short-ranges and analyse the situation for longer ranges. Practical measurements from a millimetre-wave radar system are presented to validate the theoretical modelling.