Verification of Liquid Dielectric Property Measurement by a Two-Antenna Method at Frequencies over 4 GHz

Specific absorption rate (SAR) is used as a metric for the safety guidelines of human exposure. In a recent revision of the measurement standard for the compliance testing of wireless devices, the applicable frequency range of SAR was extended from 6 to 10 GHz. Thus, the applicable frequency range of the SAR probe calibration system should also be extended to the same frequency range as that of the revised standard. In this study, we propose a dielectric property measurement method using the propagation characteristics of two antennas in a liquid. This method is the first step of the extension of the SAR calibration system. To verify the applicability of the proposed method, the dielectric properties of pure water are measured in the frequency range from 4 to 10 GHz. The measured dielectric properties are compared with those obtained using a numerical formula for pure water. From the results, we show the applicability of the proposed method from 4 to 10 GHz.