Modeling the dielectric behavior of saline soil at microwave frequencies

Soil salinization is a problem of global concern because of the economic impact and, consequently, its measurement and possible control are very important. Electromagnetic sensors such as ground penetrating radar and electromagnetic induction sensors are among the most widely used methods for the detection of soil components. This paper focuses on the dielectric behavior of saline soil at microwave frequencies. Five different soil types with varying levels of moisture and salinity were prepared in the laboratory and their dielectric properties were measured to evaluate the influence of moisture and salinity on the real and imaginary parts of the dielectric constant. An improved dielectric model for saline soil in the microwave frequency range was then developed (with two groups of equations for low- and high-frequency regions) with the regression parameters derived using the Levenberg-Marquardt and Universal Global Optimization methods. This modified model proved to be suitable for saline soil with a good degree of accuracy based on the statistics (R-2 and root mean square error) for both frequency ranges. For example, for the C band (5.25 GHz), discussion on how to use the improved dielectric model at moderate frequency is conducted. Future rigorous experiments under varying field conditions will be conducted to develop a more robust model for implementation using SAR remote sensing technology.