A passive SAW based RFID system for use on ordnance

Automatic RFID tracking of ordnance in transport or storage has been difficult or impossible due to the dangers that arise from possible accidental actuation of electro-explosive devices by RF electromagnetic fields. Limits on the maximum RF power densities that meet Hazards of Electromagnetic Radiation to Ordnance (HERO) emission standards preclude many passive RFID systems from operating safely in the vicinity of ordnance due to the high level of RF radiation needed to power the electronics onboard the RFID tag. This paper describes a Surface Acoustic Wave (SAW) based RFID system that allows safe operation of an RFID system with no standoff or separation distance between the reader antenna and the item of ordnance. Surface Acoustic Wave RFID systems are a “chipless” technology that utilize the piezoelectric properties of certain monolithic crystal materials to provide a truly passive RFID technology which can be operated at RF power levels well below those established for safety near ordnance.