Metamaterial RFID tag designs for long read range

A novel high gain metamaterial tag antenna for European UHF RFID is proposed. First a modified dog bone AMC unit cell and a meander dipole antenna are designed separately to operate in 865.6-867.6 MHz frequency band, then the effect of adding an AMC to design is investigated. The realized gain increased from 1.8 dB for the antenna alone to 4.17 dB for the metamaterial antenna constituted of 1 × 2 unit cells. A total efficiency of 90 % is observed at 868 MHz. Then the effect of increasing the number of unit cells of AMC on the performance of the tag antenna in terms of gain, bandwidth and radiation efficiency is studied. By increasing the unit cells to 2×3, the antenna gain increases to 7.66 dB with an efficiency of 95.78 %, hence increasing the read range. The structure is low cost and easy to fabricate.