Real time location system using passive UHF RFID

RFID technology is becoming more and more popular these days and on its top stands passive UHF RFID technology for it´s economical as well as practical benefits. Even though this technology is intended for inventory, several attempts have been made by several vendors in creating a real-time location tracking system using passive RFID solutions. The scope of this paper is description of experiments when developing such a RTLS with 9 RFID readers spread into a rectangular grid at the area of 64 to 100 meters square. Each reader connected to 4 antennas facing specified direction. Location algorithm combines signal strength values with number of reads to obtain tags location probability. Experiments with this settings were run in October and November 2013 at the Southern Alberta Institute of Technology, Calgary, Canada in cooperation with Dean Brennan of the RFID Application Development (RAD) Lab Team and visiting professor from Technical University of Liberec, Czech Republic (Jan Kolaja). The most interesting result of these space consuming experiments is self-calibrating algorithm. Although the system has not been sufficiently finished yet as it is limited by having not enough powerful antennas, the experiments have earned many beneficial knowledge.