Efficient Electrically Small Wide Band Planar Antenna for SAR Reduction

In this paper, an efficient electrically small wide band planer antenna for SAR (Specific Absorption Rate) is designed and fabricated. The proposed antenna consists of two inductive loading arms and inverted L-type monopole antenna. Also, the proposed antenna is designed to have a CPW feed structure and a superstrate layer. Two inductive loading arms are electromagnetically coupled with main monopole for the dual resonance mode of the antenna operation. The dual resonance characteristics are shown at 2.184 GHz and 2.44 GHz, respectively. The measured impedance bandwidth (VSWR les 2) is 624 MHz (1.984_~2.608 GHz). The proposed antenna has maximum gain of 2.8 dBi and radiation efficiency of 80.3 % at 2.184 GHz. With the arrangement that the proposed antenna is mounted at the front of the mobile handset cover plane, the radiated power difference between the forward and backward from the human head is about 10 dBi. Moreover, disadvantage of the conventional electrically small antenna, such as narrow impedance bandwidth and radiation efficiency, are improved by simple inductive loading structure.