Novel Approach for Enhanced Reduction of SAR in a Mobile Phone Antenna Using High Impedance FSS

In this paper, we investigate the performance of periodic reflecting surfaces for reducing the energy absorption of human head from a mobile phone antenna. A six-layered human head model and a conventional planar inverted-F antenna (PIFA) designed to operate at the IMT-LTE band (1.8-2.3 GHz) are chosen for specific absorption rate (SAR) analysis. The reflector is placed between the human head model and the antenna to study the amount of SAR reduction. Initially, a monolayer frequency selective surface (FSS) is modelled on an FR4 substrate with overall dimensions of 0.084λ
₀
× 0.084λ
₀
× 0.011λ
₀
and an SAR reduction by 64.7% was observed. To overcome few disadvantages of these conventional reflecting surfaces, a high impedance surface (HIS) which is a special case of FSS is designed for SAR reduction with an overall dimensions of 0.21λ
₀
× 0.21λ
₀
× 0.011λ
₀
. ( λ
₀
is the free space wavelength at 2.1 GHz). The proposed HIS showed 85.3% reduction in SAR, when compared with the SAR level observed in a conventional mobile phone and head phantom setup.