Low cost radio interrogation system for passive SAW sensors and transponders

Wireless measurement systems utilizing passive SAW sensors offer new and existing perspectives for measurement processes and identification purposes. For the majority of the applications, a small sized low cost radio request system and small antennas are necessary. In order to satisfy these requirements, on the one hand we developed an optimized RF and evaluation unit, on the other we found solutions for an antenna optimization. Consequently the presented system employs simple concepts of RF signal generation, signal windowing and data processing and an antenna concept, based on the principle of folded spiral antennas. It can be employed on both sides, at the interrogation and at the passive sensor. The principles, numerical simulation results and measurements are presented and discussed