Dual frequency based Real Time Location System using passive UHF RFID

A dual frequency based Real Time Location System (RTLS) using passive Ultra-High Frequency Radio Frequency Identification (RFID) is presented in this paper. Compared with traditional RFID location systems which mostly use RSSI measurement, the proposed approach has the unique virtue of small bandwidth requirement and high estimation resolution. The “dual frequency ranging principle” is first analyzed and the system is modeled in a simulation tool. Then some critical nonideal factors of the system are discussed and suggestions of the system´s tolerance to each non-ideal factor are given. Simulation results show that the estimation accuracy can be less than 0.5 meter with I-Q relative mismatch under 0.08 and SNR at baseband above 21.5dB.