Multibeam antenna array for RFID applications

This paper presents a high performance 2 × 2 antenna array with a Butler matrix beamforming network for RFID applications in the UHF band 860 - 960MHz. The antenna elements as well as the Butler matrix are implemented using microstrip technology. Thanks to the applied original microstrip routing technique the design is very compact and has low fabrication costs. Performed RFID bulk measurements demonstrate an improvement of the reading reliability of passive RFID tags stacked in a pallet using the proposed antenna concept in contrast to the operation with a conventional singlebeam reader antenna.