Constitutive parameter measurements of fluids and soil between 500 kHz and 5 MHz using a transmission line technique

Electromagnetic properties of soil in the 500 kHz to 5 MHz range are determined experimentally to predict plane wave propagation. The ratio of the characteristic impedance of a coaxial probe filled with fluid or soil to the same probe filled with air is used to determine the material's effective permittivity and conductivity. Open‐ and short‐circuit impedances are measured, corrected, and used to predict wave parameters. Measurements made on dry desert alluvium demonstrated the method. Wave attenuation increased linearly with frequency between 0.5 × 10−2 Np/m at 1 MHz to 2.5 × 10−2 Np/m at 5 MHz because of increasing soil conductivity; the ratio of soil wavelength to free‐space wavelength remained approximately constant at 0.4 because of the almost constant permittivity in this frequency range.