Measurement of Complex Permittivity of Tissue-Equivalent Liquid Poured in a Waveguide Well

The standard method for assessing the specific absorption rate of a mobile device involves scanning an electric field probe in a tissue equivalent liquid. The electric field probe is also calibrated in the liquid. Uncertainty of permittivity measurement of the liquid accounts for a large proportion of uncertainty of the specific absorption rate measurement and related probe calibration. The permittivity measurement of the liquid generally employs a coaxial probe method, but its uncertainty tends to be somewhat large because of its reflection measurement. In this paper, we propose a method to estimate the complex permittivity of the liquid from the attenuation and phase constants of the liquid surrounded by the waveguide well and moving the small dipole antenna in it, and show an example of actual measurement.