Characterizing wireless transmission channels for passive transponder systems

This contribution contains a combined characterization of the energy transmission channel and the transponder ASIC of passive transponder systems. This characterization takes the reader antenna as well as the transponder antenna and the reading range into account. The characterization also comprises models of the transponder ASIC's RF front-end. An automotive application, a tire pressure measurement system, is presented. The transponder is mounted on the rim. Due to wheel revolution, the transponder is periodically outside the reading range for a certain peroid. Its motion in the field of an arbitrary reader antenna is modeled depending on car velocity and car motion curvature. The characterization provides the induced voltage as a function of time. Since measurement has to be performed even at high car velocities, the time slots with the transponder being inside reading range are short. This has to be considered, when balancing the transponder's energy and designing the communication protocol.