Enabling the Use of Broadband Tissue Equivalent Liquids for Specific Absorption Rate Measurements

The aim of this study is to determine a robust prediction algorithm for the change in SAR due to deviations in the complex permittivity of a homogeneous phantom from standardized reference values. Several antenna sizes and distances to the phantom are investigated so as to study a large range of SAR distributions. Simulations using the Moment Method are presented. Results are analyzed over a frequency range of 30 - 6000 MHz. It is demonstrated that the prediction algorithm, while developed using dipole antennas, also works well for realistic wireless devices. Employing the prediction algorithm reduces the SAR measurement uncertainty due to permittivity changes, thereby improving the reproducibility of SAR compliance assessment between laboratories. Another benefit of the algorithm is that it enables SAR measurement standards committees to relax their tolerances on the complex permittivity from defined targets, which allows for the use of broadband tissue equivalent liquids, thus reducing the cost of SAR measurement. The method presented in this paper has been adopted for inclusion in the next revisions of the IEEE 1528 and IEC 62209 measurement standards.