Near-Field/Far-Field Transformation for Estimating Direction of Arrival with Bistatic MIMO Radar

Object detection with millimeter-wave radar is required for many applications, such as driver assistance and health care systems. The major challenges for these applications are reduction of miss detection and high-resolution detection in the near field. The signals received at array antennas in bistatic multi-input/multi-output radar lack a far-field condition at short ranges. Therefore, conventional receive beamforming cannot be applied to determine the direction of arrival. In this paper, we propose a receive beamforming method with near-field/far-field transformation. The measurement results using radar modules show that our proposal method formed a sharp main beam for a target at short range and separated nine adjacent targets.