3D microwave vibrometer: Contactless three-dimensional vibration measurements using microwave radars

•An innovative three-dimensional vibration measurement method using microwave radars is proposed.•Accurately reconstruct three-dimensional vibration trajectory of target and measure its displacement at three orthogonal axes using three single microwave radars’ vibration measurement results.•Theorical error analysis is done to give out the factors and their upper bounds that influence the 3D vibration measurement results.•Simulation and experimental validations with different scenarios are presented to demonstrate the performance of our proposed 3D microwave vibrometer.