Microwave analysis and experimentation for improved backscatter radio

This work aims to improve the RFID RF front-end performance via microwave analysis. It is well known that the magnitude of the complex reflection coefficient difference, between two loads connected to the tag-antenna, is a crucial design parameter. On the other hand, the loads are usually considered ideal and there is no microwave analysis of electromagnetic interference between the antenna and the load control circuit. This study demonstrates through measurements that the assumption of ideal loads is not realistic and magnitude of reflection coefficient difference is reduced in practice, offering degraded backscatter radio performance (compared to the ideal case). A microwave analysis is utilized in order to assess coupling between the control circuit and the antenna/RF switch (that selects the loads). As a collateral dividend, the magnitude of reflection coefficient difference is increased with microwave analysis and experimental measurements and a specific methodology is proposed.