Radio frequency sounding on glaciers and on the moon

In most geologic environments the electrical conductivity is sufficiently high that useful electromagnetic sounding is restricted to low frequencies where diffusion of energy into the earth is dominant. In some environments the resistivity is sufficiently high that it is possible to get considerable depths of penetration using frequencies in the 1 Mhz to 100 Mhz range so that one can deal with conventional wave propagation. One such material is ice which behaves as a dielectric with a frequency-dependent loss. The dielectric constant is typically about 3.2 - 3.3 and the loss tangent is typically where is in Mhz. By measuring the field strength as a function of distance from a fixed transmitter it is possible to detect interference between the surface wave, the subsurface wave and any reflections. This gives a determination of dielectric constant, loss tangent and depth to reflectors.