Broadband UHF RFID tag antenna with a rectangular‐loop feed and additional patches

A novel tag antenna with a rectangular‐loop feed, a bent meandered strip and additional patches is designed and analyzed in ultra high frequency (UHF) radio frequency identification (RFID) bands to provide broadband, high gain, and size‐reduction performance simultaneously. It is designed to operate at UHF RFID bandwidths, with resonant frequencies of 842, 868, and 915 MHz, respectively. The dimension of the antenna with resonant frequencies of 915 MHz is around 78 × 23 mm2, which shows near linear phase characteristics. Simulated and measured results show the proposed antenna can obtain 100 MHz bandwidth under the condition of voltage standing wave ration less than 2 and 1.6 dBi gain for worldwide UHF RFID bands. In addition, the antenna provides a good radiation pattern.