The task of detecting and locating landmines, unexploded ordnances (UXO) and improvised explosive devices (IEDs) is still a major challenge up to the present day. Problems such as the distance between the hazardous area and the measurement system as well as the differentiation between the target of interest and the surrounding soil are of importance in the development of the sensor system. Various types of radar based systems have been developed over the last decades to solve these problems. Compared to other methods ground penetrating synthetic aperture radar (SAR) has the ability to scan large areas from a safe standoff distance in a relatively short time. In this paper, two different imaging radar systems are compared. The first one is a ground-based SAR (GB-SAR) developed at German Aerospace Center (DLR). The other system is an unmanned aerial vehicle-based SAR (UAV-SAR) from the University of Ulm. The presented data originates from a joint campaign using the same measurement scenarios.