Abstract:When Ultra High Frequency Radio Frequency Identification (UHF RFID) tags in dense cloth environment, the work frequency of stacked RFID tags will be deviated by the mutual influence between the tag antennas, and the system read rate will be declined. This paper designed a new type of circular polarization reader antenna, which works in the UHF frequency band, has the characteristics of miniaturization, high gain, and wide band. In this antenna, the main radiation circular patch is connected up and down by four probes to the matching network, which can effectively improve the circular polarization axial ratio bandwidth and work bandwidth of antenna. The simulation results show the antenna has 13% bandwidth of impedance and 5% bandwidth of 3 dB axial ratio, and 9.4 dBi gain in the UHF frequency. In the open environment, we test the tag read rate of intensive multiple RFID tags. The experimental results show that the wide band RFID reader antenna is available.