HYBRID LOOP ANTENNA FOR 2.4-GHz RFID TAGS

Recently, more and more research activities have been focused on the radio frequency identification (RFID) systems due to their applications in the supply chain management and the security identifications. Most RFID systems consist of a reader/writer and a tag [1]. The reader transmits RF power to the tag, which then sends a unique coded signal back to the reader, while the writer can change the information contained within the tag. Several frequency bands have been assigned to the RFID applications, namely 125 KHz, 13.56, 869, and 902-928 MHz, and 2.45 and 5.8 GHz. As the operating frequency for RFID systems rises into the microwave region, the antenna design becomes more acute and essential [2]-[4]. Besides the requirements of the impedance and radiation performances, the conformal structure and the compact size are the main concerns within the design process. In this paper, we present a miniature hybrid loop antenna with the RF performances suitable for the RFID tag use at 2.45-GHz.