Soils are lossy media characterised by a conductivity s DC and a complex permittivity e ' - j e ''.
The real part of the permittivity e ' is a measure of the ability of the medium to be polarised under an electric field. For the high frequency range the dipoles can not follow the fast change in magnitude of the field, and the polarisation will be out of phase, there is a relaxation phenomena. The second exponential term represents the propagation, the phase is controlled by the phase constant b . The constants are defined by the soil characteristics. That is more than enough for minedetection.