Using a circularly polarized patch antenna to optimize the passive UHF RFID indoor channel

In this paper we describe the design and performance of a new circularly polarized broadband patch antenna for RFID applications. It works both in the current European UHF range (865 MHz - 868 MHz) and the new European UHF range according to ETSI TS 102 902 (915 MHz - 921 MHz). Simulations show that circular patch antennas improve the multipath behavior of the channel significantly. In [2] we show that switching the system frequency strongly improves the channel's fading characteristic. Because an RFID system can be equipped with the new antenna for readers and tags we can make use of both beneficial effects to increase tag read probabilities and read ranges in typical indoor environments. RSS measurements are used to verify the simulation results and to quantify the performance of the new antenna.