Assessment of Volumetric Water Content Using Radio Waves

Volumetric water content evaluation in structures, substructures, soils, and subsurface in general is a crucial issue in a wide range of applications. The main weakness of subsurface moisture sensing techniques is usually related both to the lack of cost-effectiveness of measurements, and to unsuitable support scales with respect to the extension of the surface to be investigated. In this regard, Wireless Underground Sensor Network are increasingly used non-destructive tool specifically suited for characterization and measurement. It is undeniable that wireless communication technology has become a very important component of modern society. One aspect of modern society in which application of wireless communication technologies has tremendous potential is in agricultural production. This is especially true in sensing and transmission of relevant farming information such as weather, crop development, water quantity and quality, among others, which would allow farmers to make more accurate and timely farming decisions. Although many systems are commercially available for soil moisture monitoring, there are still many important factors, such as cost, limiting widespread adoption of this technology among growers. Our objective in this study was, therefore, to develop and test an affordable wireless communication system for monitoring soil moisture. WUSN is a specialized kind of WSN that mainly focuses on the use of sensors at the subsurface region of the soil, that is, the top few meters of the soil. This thesis emphasizes on comparison of experimental measurements conducted with wireless devices based on LoRa using point to point communication to the advanced channel models (precisely on single-path channel model) that were developed to characterize the underground wireless channel considering the characteristics of the propagation of EM waves in soil and their relationship with the frequency of these waves, the soil composition, and the soil moisture.