This paper presents a localization method exploiting a mobile robot equipped with an Ultra High Frequency Radio Frequency IDentification (UHF-RFID) reader to locate stationary tags in warehouse scenarios. The measurement method is based on the Synthetic Aperture Radar (SAR) approach and the robot trajectory knowledge is achieved through a calibrated vision-based system suitable for indoor environments. The technique capability is demonstrated through an experimental analysis employing commercial UHF-RFID hardware and a wheeled robot. Localization accuracy is evaluated on the field by using a calibrated vision system, used to both locate the robotic vehicle and the tags when detected.