Achieving long reading ranges with passive wireless intermodulation sensors

This paper presents a system architecture combining batteryless wireless intermodulation sensors and their associated reader, and analyses the achievable read range of such sensor-reader system. The computed read range is compared to those provided by harmonic and passive UHF RFID sensor systems. Effects of both reader thermal noise and third-order distortion by the reader itself on the read range of the system are considered, by means of theoretical analysis, simulations and measurements. The presented reader with a distortion-limited sensitivity of -70 dBm at the receiver input provides a 7 m measured and a 9 m simulated read range.