A Practical Concept for Precise Calibration of MIMO Radar Systems

The calibration of MIMO radar systems is crucial to compensate complex gain and mutual coupling errors of antenna arrays, thereby enabling a good measurement performance. With the increased importance of automotive MIMO radar sensors, there is a need for a reliable calibration procedure with low requirements on the calibration setup and the necessary reference system. Especially concepts for in-situ and re-calibration of already installed radars with deteriorated performance due to aging and/or possible deformation, are required to match the high safety standards in autonomous driving. Recently, we proposed a calibration approach for receive antenna arrays, i.e. SIMO systems, which solely requires relative position information to create a synthetic aperture with the radar. In this paper, this approach is extended to cope with MIMO systems, thereby estimating the mutual coupling matrices associated with the transmit and the receive antenna array. Furthermore, the special case of uniform linear arrays is discussed. The MIMO calibration is successfully validated by measurements with a commercial 76 GHz MIMO radar.