The purpose of this text is to provide the reader with a fair number of elements to understand what a SAW (Surface Acoustic Wave) device is and what its possible applications are, in particular to analyze the specific case of wireless sensors. The second chapter presents some of the most significant mathematical models for describing the behaviour of SAW devices. Then is analyzed the development of a transponder model based on a Two-Port SAW resonator to read a commercial PT100 temperature sensor. The device is made by photolithography on asubstrate of LiNbO3 and then characterized through the use of a Vector Network Analyzer (NanoVNA). Finally, some considerations are made about wireless measurements.