3D localization of passive UHF RFID transponders using direction of arrival and distance estimation techniques

The present publication describes a localization concept to determine the 3D Position of passive UHF-RFID transponders. The importance of accurate location information significantly increases with Industry 4.0 in mind. Various applications in production and logistics require the exact location for monitoring the processes and thereby increasing the quality and reliability. The presented system consists of an 8 channel superheterodyne receiver with a connected 2D L-shaped patch antenna array controlled by a standards-compliant UHF reader. The recorded backscattered signal from the transponder gets evaluated by 2D versions of Bartlett Beamforming and MUSIC algorithm using a calculated 2D array manifold. For distance estimation the phase of the backscattered transponder signal gets evaluated for different reader transmission frequencies in the UHF band by applying a modified MUSIC algorithm. By measuring the distance, azimuth and elevation angle a monostatic 3D localization of the passive transponder is possible. For validation the localization concept is examined under ideal conditions in an anechoic chamber and in an industrial environment to show the overall performance.