Free-Space Dielectric Property Measurement of Biological Tissues at W-Band Frequencies

This paper presents a free-space measurement method for the dielectric properties of small biological tissues (in this study, micropig skins that are 60 mm × 60 mm in size and 1.4 mm in thickness are used) that do not meet the size requirement of conventional free-space material measurement at W-band (75–110 GHz) frequencies. The first step involved enhancing the material under test (MUT) holder of an existing free-space material measurement system to ensure the reliable measurement of small biological tissues. This enhancement was confirmed by comparing the measured dielectric properties of an air gap with its theoretical properties. The measured dielectric properties of the micropig skins were then validated through a comprehensive comparison using data based on the double Cole-Cole parametric model, which is a widely referenced model in many numerical dosimetry studies. The good agreement between the two results demonstrates the effectiveness of the proposed free-space material measurement method, as well as the reliability of the measured dielectric property of micropig skins.