DIELECTRIC-PROPERTIES AND INFLUENCE OF CONDUCTIVITY IN SOILS AT ONE TO 50 MEGAHERTZ

A series of laboratory experiments were performed in order to systematically explore the dielectric response of soils to a frequency range of 1 to 50 MHz. A network analyzer and a coaxial-transmistion-line type of dielectric probe were used to measure the complex (both real and imaginary) dielectric response of moist soils. The dielectric probe was placed in a modified Tempe cell in which the moisture content of the soil under investigation could be varied. Both the real and imaginary components of the dielectric permittivity of the moist soils investigated are greatest at 1 MHz and monotonically decrease with frequency. A Looyenga-type mixing model incorporating ionic conductivity can account for the frequency dependence of the dielectric constant of wills.