New concepts of wireless interrogable passive sensors using nonlinear components

A new wireless interrogation principle using passive nonlinear components in alliance with state of the art passive impedance sensors is introduced in this contribution. Most currently available passive wireless sensor systems use time division to separate radio request and sensor response on the radio channel, requiring extensive signal processing effort. In order to avoid this, we evaluate and discuss our new concept utilizing frequency domain division. Therefore, passive circuits consisting of a nonlinear device, e.g. a diode, permalloy bar, etc., affected by the impedance of conventional sensors are used. The sensor information is found in the magnitude difference of the intermodulation distortion products. Simple coherent demodulation is used for read out. Numerical simulation results compared with measurements are presented and discussed.