High Gain and High Efficiency UHF Tag with Enhanced Complementary Spilt Ring Resonator Metamaterials

A passive, high gain and high efficiency RFID tag antenna with two kinds of enhanced complementary spilt ring resonator (ECSRR) units is proposed in this paper. The tag is composed of a centered folded dipole and period-arrayed metamaterials bilaterally, which named top /bottom bad circle ECSRR (TBCSRR/BBCSRR) units. Simulated results show that the tag's working band is 908 MHz-927MHz. The return loss is 33.7dB, realized gain is 3.92dBi, the 3dB beam width is 184°, the total efficiency and power transmission coefficient are 82.4% and 0.9996, respectively, at the best resonance frequency of 916.7MHz. The maximum reading distance of the tag is 25.8m when the Effective Isotropic Radiated Power (EIRP) is 2W and 36.5m when it is 4W at 916.7MHz.