A coherent multi-reader approach to increase the working range of passive RFID systems

A multi-reader system is presented which is capable of increasing the working range of passive RFID systems. This gain in range is obtained by using constructive superposition of the readers' RF waves. A coherent multi-reader demonstrator system has been designed that consists of two reader units and one central unit. The demonstrator system operates in the UHF band and allows for an arbitrary distributed placement of its units. Simulation results and indoor measurements are presented, which show a significant larger range of the multi-reader system in comparison to a single-reader.