Microwave characterization of human skin in vivo for frequency ranges 8-12.5 GHz and 18-26 GHz.

In this paper, the dielectric properties of human skin in vivo were measured in the frequency range 8 — 12.5 GHz and 18 - 26 GHz. The work involved testing of several human subjects by pressing an area of the human body against a waveguide sensor. The measurement system consists of a Vector Network Analyzer (VNA) Wiltron 37269B and open-ended waveguide sensor. The waveguide sensor consists of coaxial cables, coaxial-to-rectangular waveguide transition, and Teflon™ impedance transformer. Complex reflection coefficients (Sn) were measured and complex permittivities (e*) are calculated by implementing a formulation of a rectangular waveguide radiating into the half-space of lossy dielectric material. Results are reported for the mean value of 20 (male and female} subjects for the palm region of human skin in vivo. Also, complex permittivities of the sole region of human skin in vivo are reported for the mean value of 5 male subjects.