A circular patch antenna with parasitic element for UHF RFID applications

This article initially proposes a directly-fed circular patch antenna with L-shaped ground plane for Radio Frequency Identification RFID applications in the 900 MHz 902-928 MHz ultrahigh frequency UHF band. To achieve circularly polarized CP radiation, two arc-shaped notches are loaded into the main patch. To enhance the CP bandwidth so that the proposed antenna can also cover the UHF RFID band for Europe 866-869 MHz, a parasitic element is printed besides the main patch. Experimental measurements show that the 10-dB return loss bandwidth of the proposed antenna was 30.95% 833-1138 MHz and its corresponding 3-dB axial ratio bandwidth was 8.95% 865-946 MHz. Good gain and radiation efficiency of more than 7 dBic and 90%, respectively, were also exhibited across the two desired UHF RFID bands. © 2015 Wiley Periodicals, Inc. Int J RF and Microwave CAE 25:681-687, 2015.