Effects of using conductive materials for SAR reduction in mobile phones

Adding an external shield to mobile phones is one of the common methods adopted for the reduction of the specific absorption rate (SAR), which is the safety level of human exposure to radiated electromagnetic fields from mobile phones. This paper provides an experimental study on the effectiveness of SAR reduction by attaching conductive materials to mobile phones, and the corre-sponding effects of the antenna performance of the mobile phones. The results show a typical trade-off of a 20% reduction in the SAR value with a maximum 1.8-dB reduction in the received power of the antenna. The results also conclude that the attachment position of the shielding material is an important factor, whereby the hot spot of the SAR distribution of the mobile phone must be well covered in order to achieve good SAR reduction. ©2004 Wiley Periodicals, Inc.