Readout scheme for resistive chipless wireless sensors

A readout scheme for resistive chipless wireless sensors is derived from a systematic analysis of the signal flow in a generic reader-tag-system. The mathematical model is based on assumptions of tag, reader and channel properties. It is shown, that with a tailored tag antenna design the maximal operation range can be significantly extended since only two of three calibration measurements are necessary and the measurement with the weakest response in signal level can be omitted. With this approach at least a 30% increase in operation range can be expected. Experiment with sensor tags based on patch and PIFA antennas, loaded with temperature dependent resistive sensors, prove the concept.