This paper presents the application of the phase-based SARFID technique to locate static tags with respect to a UHF-RFID reader carried by an Unmanned Grounded Vehicle (UGV). The UGV can autonomously move inside a complex indoor environment avoiding obstacles as it exploits Laser Range data to create a real-time map of the scenario. The knowledge of the reader antenna trajectory is achieved through a Simultaneous Localization and Mapping (SLAM) procedure. The bi-dimensional tag position can be estimated with centimeter accuracy by employing the SARFID technique with two reader antennas. Differently from other localization techniques, neither reference tags (anchor tags) nor large phased array antennas are required