Negative Permeability Metamaterial Structure Based Electrically Small Loop Antenna

In this paper, negative permeability metamaterial structure based electrically small loop antenna is built and tested. The size of proposed antenna is ka = 0.27 by Chu limit. The experimental result shows that the resonant frequency and impedance bandwidth (VSWR les 2) are 910.76 MHz and 6.7 MHz (908-914.7 MHz). The proposed antenna has maximum gain of -1.302 dBi and radiation efficiency of 21.43% at 910.76 MHz. Although the proposed antenna has very small size, maximum gain and radiation efficiency of proposed antenna show good performances. The proposed antenna is efficiently matched and designed by equivalent circuit model. The proposed antenna is fabricated simple metamaterial structure without additional matching network and printed on a dielectric substrate without ground plane. Therefore it has advantages of low cost, small size, and light weight and will be applied to wireless communication systems for required small antennas, such as RFID (radio frequency identification).