SAW delay lines for wirelessly requestable conventional sensors

Programmable reflectors of SAW ID-tags can be employed as passive transponders for conventional sensors of the capacitive, inductive and resistive type. The programmable reflector is a loadable split finger transducer, other fixed reflectors are used as reference bits. A noncoherent read out signal processing is sufficient, because the load of the programmable reflector influences both the phase and amplitude of the reflected wave. The principle is discussed, setup and results of some actual measurements are presented.