A half-space electromagnetic model of human skin over the band 30–300 GHz was constructed and
used to model radiometric emissivity. The model showed that the radiometric emissivity rose from 0.4
to 0.8 over this band, with emission being localized to a layer approximately one millimeter deep in
the skin. Simulations of skin with differing water contents associated with psoriasis, eczema,
malignancy, and thermal burn wounds indicated radiometry could be used as a non-contact technique
to detect and monitor these conditions. The skin emissivity of a sample of 30 healthy volunteers,
measured using a 95 GHz radiometer, was found to range from 0.2 to 0.7, and the experimental
measurement uncertainty was ±0.002. Men on average were found to have an emissivity 0.046 higher
than those of women, a measurement consistent with men having thicker skin than women. The
regions of outer wrist and dorsal forearm, where skin is thicker, had emissivities 0.06–0.08 higher
than the inner wrist and volar forearms where skin is generally thinner. Recommendations are made to
develop a more sophisticated model of the skin and to collect larger data sets to obtain a deeper
understanding of the signatures of human skin in the millimeter wave band.