Design of patch antenna for RFID reader applications

In this paper a single feed circularly polarized patch antenna and a constructed prototype ideal for Gen2 RFID (Generation 2 of Radio frequency identification) reader applications is present. The proposed patch antenna has a simple structure, it have corner truncated square patch, ground plane and a feed line with L-shaped of ground coupled. Through a via hole in the vertical ground of the ground plane, the radiating patch is easily excited by an L-shaped coupled feed oriented in the same plane as the patch, and circular polarization (CP) radiation is achieved. Experimental results of a constructed prototype with the center operating frequency at about 922 MHz showed that the patch antenna has an impedance bandwidth (1.5 : 1 VSWR) of about 10%, return loss S11 of about -26 dB and a gain level of 8.5 dB. In addition to the proposed patch antenna due to its simple structure, the obtained CP performance with low cost is among the best that have been reported for single-feed single-element patch antennas.