I. Introduction
Radar sensors play an important role in the environment perception of modern autonomous robot systems. This is especially true for outdoor applications that require a large field of view of 100 m or more. Here, radar stands out against other sensor technologies like camera and lidar due to its long range and robustness to adverse weather conditions such as rain or fog [1]. Moreover, it allows for a direct measurement of the velocities of objects. For these reasons, research is driven particularly by the automotive sector, where radar sensors are vital to the development of new driver assistance systems and a continuously rising degree of automation.