High-Gain and High-Efficiency Flexible Nonsymmetrical Metamaterial Tag

A flexible nonsymmetrical metamaterial tag with high gain, high efficiency, and wide readable angle range is proposed here, whose working band is 900–930 MHz. We improved impedance match between tag's antenna and chip to reduce the mismatch loss and increase radiation efficiency of the tag by loading border cross units with top or bottom defaulted units above and below the central folded dipole. Furthermore, the proposed tag is in the size of 95 mm×57 mm×0.23 mm, and it can realize 5 dBi realized gain, radiation efficiency of 89.13%, and 54 m reading distance when the reader's effective isotropic radiated power is 42 dBm if it is on a plane. When it is conformal to cylinders whose radius is over 26 mm, the tag also can work at 900–930 MHz, perform over 80% efficient, and realize over 35 m reading distance in measurement.