  Radar is highlighted for robust sensing capabilities in adverse weather
conditions (e.g. dense fog, heavy rain, or snowfall). In addition, Radar can
cover wide areas and penetrate small particles. Despite these advantages,
Radar-based place recognition remains in the early stages compared to other
sensors due to its unique characteristics such as low resolution, and
significant noise. In this paper, we propose a Radarbased place recognition
utilizing a descriptor called ReFeree using a feature and free space. Unlike
traditional methods, we overwhelmingly summarize the Radar image. Despite being
lightweight, it contains semi-metric information and is also outstanding from
the perspective of place recognition performance. For concrete validation, we
test a single session from the MulRan dataset and a multi-session from the
Oxford Offroad Radar, Oxford Radar RobotCar, and the Boreas dataset.
