Water-filled testbed modeling, design, and fabrication for performance validation of a holographic subsurface RADAR antenna

The characterization of microwave subsurface holographic RADAR sensors is not simple because the investigated medium is generally not homogeneous, and the soil electromagnetic properties change with moisture content. Commonly, holographic radars designed for terrain investigations use sand-box testbeds. To ensure the homogeneity of the medium and a well-defined value of dielectric permittivity and conductivity (attenuation), we designed and fabricated a testbed filled with water. With a solution of Sodium Chloride concentration at room temperature, it is possible to obtain a specific dielectric permittivity and the desired attenuation. In this paper we describe the design process, the fabrication, and a preliminary experiment with distilled water using a plastic candy box as a target. This approach to the fabrication of a RADAR testbed guarantees the repeatability of the measurements reducing the number of uncontrolled variables in laboratory experiments.