This paper presents the application of the phase-based SARFID technique to locate static tags through an Unmanned Grounded Vehicle (UGV) equipped with a UHF-RFID reader. The UGV is remote-controlled to move inside an indoor environment and the knowledge of its trajectory is achieved through a Simultaneous Localization And Mapping (SLAM) procedure. The bi-dimensional tag position can be estimated with a location error in the order of few centimetres if the phase samples are collected in a proper spatial interval. Differently from other localization techniques, neither reference tags (anchor tags), nor large phased array antennas are required.