SAR-GPR is a sensor system composed of a GPR and a metal detector for landmine detection. The GPR employs an array antenna for advanced signal processing for better subsurface imaging. This system combined with synthetic aperture radar algorithm, can suppress clutter and can image buried objects in strongly inhomogeneous material. SAR-GPR is a stepped frequency radar system, whose RF component is a newly developed compact vector network analyzers. The size of the system is 30cm × 30cm × 30cm, composed from 6 Vivaldi antennas and 3 vector network analyzers. The weight of the system is less than 30kg, and it can be mounted on a robotic arm on a small unmanned vehicle. In the signal processing of the SAR-GPR has a unique future. It can be used with an algorithm for strong clutter suppression. The sensor has about 10cm offset from the ground surface, and it can even image the ground surface topography. It will be implemented for more advanced imaging algorithm, which can be used for the ground surface with a large roughness. Field tests of SAR-GPR were carried out in March 2005 in Japan. Then after, it was also evaluated in the Netherlands and Croatia. We report the results of these evaluation and demonstration.