In the thesis, we propose an intelligent metamaterial to reduce the specific absorption rate (SAR) of cellular phone to phantom. We call our design intelligent metamaterial because it will not affect the antenna performance greatly. When the antenna is close to the phantom, the metamaterial acts like a stopband filter, thus reducing the SAR. We design a small metamaterial cell resonating at GSM 900 band, having 2 cm x 2cm x 0.4 cm in size. We use three cells to shield the PIFA antenna and the SAR is reduced by 29.12 % at a distance of 15 mm away from the phantom. Then we design a metamaterial cell having 1 cm x 1.95 cm x 0.4 cm in size,operating in GSM 1800 band. We use four cells to shield the PIFA antenna and the SAR reduced by 40.2 % at a distance of 15 mm away from the phantom. We also propose a dualband (GSM 900/1800) metamaterial having 2 cm x 4 cm x 0.8 cm in size. We use nine metamaterial cells to shield the dualband antenna and the ground¡Athe SAR reduced by 25 % at 900 MHz and 32.6 % at 1800 MHz at a distance of 15 mm away from the phantom.

In this thesis, intelligent metamaterial was designed to reduce the peak specific absorption rate (SAR) value. Intelligent metamaterial means that when the antenna is far away from a human head, the metamaterial behaves like air and it does not affect the antenna performance; when the antenna is close to a human head, however, the metamaterial acts like a single negative (SNG) material. We designed two kinds of intelligent metamaterial structures. One makes use of impedance mismatching, and the other makes use of the frequency band shift property to reduce the peak SAR value at the operating frequency. The former structure is broadband, and it can reduce the peak SAR value by 56.7%. The latter structure has a much smaller size compared to the former one, and it is suitable for cellular phone applications. The peak SAR value can be reduced by 40% using the latter structure. The proposed two kinds of the intelligent metamaterial structures do not affect the antenna performance. Finally, the intelligent metamaterial has been applied to a cellular phone. The dimension of the intelligent metamaterial is only 40 mm ¡Ñ 20 mm ¡Ñ 0.8 mm. The intelligent metamaterial does not affect the antenna performance when the antenna is far away from a human head. When the antenna is close to a human head, the peak SAR is reduced by 41.7%.