Millimeter-wave characteristics of fallen snow

This paper describes the measured 50- to 75-GHz band refractive index, comp lex dielectric constant, and penetration depth of fallen snow (fresh and co rn snow) in the suburbs of Eniwa City in Hokkaido, Japan, calculated from t he propagation delay time and loss measured through the sampled naturally p iled snows, in order to apply millimeter waves to road traffic control safe ty and detection of buried materials or road signs in/under the fallen snow . We show that the real part of the dielectric constant depends linearly on snow density, and the penetration depth of corn snow is much smaller than that of ice and fresh snow, after statistically evaluating data measured in different directions and in different parts of the samples. We also descri be the experimental difficulty of detecting three types of metals buried in naturally piled 30-mm-thick packed snow and in 50-mm-thick fresh snow (bur ied corner-cube reflector). (C) 1998 Scripta Technica.