A novel broadband patch antenna for universal UHF RFID tags

Abstract

A compact broadband patch antenna is proposed in this paper for global ultra-high-frequency (UHF) RF identification (RFID) applications. The antenna is composed of four synchronous shorted patches that resonate at four different frequencies, broadening its impedance bandwidth. A central loop is incorporated to feed the four patches simultaneously, which provides the required input reactance for matching to the chip as well. Since the current of neighboring patch is vertical to each other that they can radiate well without canceling each other, the gain is stable over the whole frequency band. Prototype is fabricated and tested, which shows that the impedance bandwidth can cover the whole UHF RFID band (840 MHz - 960 MHz), and the read range is over 3 meters when EIRP is set to 30 dBm at the reader. © 2010 Wiley Periodicals, Inc.