Impedance loaded SAW-sensors offer a wide range of measurement opportunities

SAW ID-tags can be employed as passive transponders for conventional sensors of capacitive, inductive and resistive type. An interdigital transducer (IDT) is used as a loadable reflector, other fixed reflectors are used as reference bits. The load of the programmable reflector influences both the phase and amplitude of the reflected wave. The principle is discussed, applications for the measurement of light, pressure and temperature are presented.