Electromagnetic Attenuation Properties of Clay and Gravel Soils

The electromagnetic attenuation properties of clay and gravel soils were measured as a function of moisture content and frequency. Measurements were done at frequencies in the 0.5 to 4.5 GHz range. Soil samples were compounded in the laboratory at approximately 10, 50, and 90 percent saturation. Sample thickness was in the range of 2.5 to 20.3 cm. Each homogeneous sample was sealed in a polyethylene container to retain the total moisture and maintain a constant moisture profile with depth. The results indicate that this method cannot satisfactorily determine the thickness of gravel or clay soil layers over a range of moisture contents which woild be experienced in field conditions.