SAR Evaluation of Wireless Communication Devices with a Multi-frequency Operation

The procedures of evaluating the SAR due to wireless communication devices are well documented, in ICNIRP, in IEEE 1528 and in EN62209-1 [1-5]. They are mainly referred to a single frequency operation.Many wireless connections are now being integrated into a single electronic device for multi-functional operation, such as PDA phone with WLAN and Bluetooth functions, and the device is operating simultaneously with more than one frequency. The concern for human safety of using wireless communication devices requirement are hence further extended to the simultaneous multiple source/frequency radiations.Using method of superposition, by assuming that the SAR evaluation of SAR at different frequencies is accumulating, for example, as described in ICNIRP or IEEE C95.1, simply by summing up the power dissipating in a root-mean-square fashion is not correct, this is due to that the main parameters, dielectric constants and the conductivity of human tissues,eand σ, in SAR evaluation are not constant with respect to frequency, and that field distribution in tissue could be complicated in multi-mode/frequency resonance in the localized portion of human body due to this non-linearity. This scenario of multifrequencies radiations from a single personal wireless device has not yet been fully addressed in current SAR assessment documentation, however the new IEC standard of IEC 62630[6], covering some scenario of multiple-source radiation, has been published June this year; some pre-specifications has been released.This proposal aims to address the approach of evaluation of SAR in human safety concern of using wireless communication devices with simultaneous multiple frequency radiations, and concentrate on the investigation on the impact of simultaneous multiple sources on SARs induced in the human body according the new test procedures.