Coherence multiplexed passive wireless SAW RFID tag system

This paper discusses a novel coherence multiplexed system for passive surface acoustic wave (SAW) RF-identification (RFID) tags. The method is adapted from optical coherence-domain reflectometry (OCDR) which is widely used today in optical coherence tomography (OCT) for medical applications. The paper discusses the coherence multiplexing technique as applied to SAW RFID. A broadband white Gaussian noise source is used as the interrogation signal and one of the major advantages is the large signal dynamic range obtained. A prototype transceiver system was built at 915MHz and used for wireless interrogation of SAW tags. The signal processing technique is discussed and the results of wireless multiplexing of four RFID SAW tags are shown.