Planar Artificial Transmission Lines Loading for Miniturization of RFID Printed Quasi-Yagi Antenna

A compact omnidirectional printed quasi-Yagi antenna for RFID reader application is presented. To reduce the size of the antenna, the radiating elements of the quasi-Yagi antenna are replaced by artificial transmission lines (ATLs). The proposed antenna that operates at 915 MHz has a substrate size of 52×77mm², which shows more than 76.24% size reduction in comparison to the previously reported compact Yagi antenna. At the center frequency, the antenna has an input impedance of 46.66-j4.27 Ω, radiation efficiency of 98.2%, and a gain of 1.84 dBi. The experimental data are in good agreement with the simulation results.