A compact broadband patch antenna for UHF RFID tags

A small broadband patch antenna for RFID tags is proposed in this paper. Using inset-feed technique together with two asymmetrical slots embedded from two non-radiation edges deep into the center of the square patch, two resonances with similar radiation characteristics can be excited. It thus increases the bandwidth of the antenna. The two slots can also reduce the size of the patch, and the inset feeding provides the required input reactance for matching as well. A prototype is fabricated and tested, which shows that half-power bandwidth of this small tag antenna (65 mm by 65 mm by 2 mm) can cover the entire UHF band (860 MHz - 960 MHz). The read range is over 2 meters when mounted on metallic platform.