Applications of shielding techniques to reduce SAR induction in human head

The regulations on the specific absorbing rate (SAR) (ANSI/IEEE C95.1-1992) has encouraged the development of technologies to reduce SAR. This paper proposes shielding techniques to reduce SAR while retaining the antenna performances as much as possible. The applications consider monopole antennas as demonstrating examples for the reason for omni-directional radiations, and propose magnetic materials to design shielding structures. It was noted that near magnetic field has been shown to be the major cause of SAR (A. Drosses et al. IEEE Trans. Microwave Theory and Tech., vol. 48, no. 11, pp. 1988-1995, 2000), and magnetic materials tend to be a good choice in this case. In the examinations the shielding structures are implemented with the antennas and also the handset box structures. The objectives are to integrate the shielding structures into the antenna and handset design, and therefore retain the integrity of the handset. Numerical studies based on finite difference time domain (FDTD) are presented.