Near-Field Loop Antenna with Magnetic Field Enhancement Using Artificial Transmission Line

The near-field loop antenna with magnetic field enhancement using artificial transmission line (ATL) is proposed in this work. At first, the working principle is revealed with the unit cell. It is seen that due to the loading of the ATL the current distribution on the meandering line becomes strong while its direction is unchanged, and thus the magnetic field is enhanced. Then, the proposed antenna is designed and tested at 915 MHz for Radio-frequency identification (RFID) application. Compared to the reference loop antenna without the ATL, the proposed antenna can generate a stronger and more uniform field distribution. In addition, the proposed antenna has a compact size of 0.37λ × 0.37λ Due to its advantages, it is potential for the application where there is a limited space.