Multirelaxation Generalized Refractive Mixing Dielectric Model of Moist Soils

In this letter, a multirelaxation generalized refractive mixing dielectric model (GRMDM) for moist soil is proposed and substantiated in the frequency range from 0.04 to 26.5 GHz. This model is based on the methodology of a single-relaxation GRMDM which accounts only for the dipole relaxation of water molecules in the gigahertz frequency range. The proposed multirelaxation GRMDM takes into account both the dipole (Debye) and ionic (Maxwell-Wagner) relaxations of soil water molecules. For this purpose, it uses a two-frequency Debye relaxation equation for the dielectric spectra of bound water. The spectroscopic parameters of the multirelaxation GRMDM were derived by fitting the spectra calculated by this model to the respective measured ones. The main advantage of this model is that it predicts the complex dielectric constant of moist soils throughout the megahertz and gigahertz frequency ranges with the same error as the single-relaxation GRMDM does only in the gigahertz range.