Underground Propagation Models and Antennas for Radiofrequency Tomography

The knowledge of appropriate techniques to detect the presence of underground voids and objects without the need to drill holes has always been of particular interest to mankind, in particular in the military and archaeological environments. During the last years, several techniques have been deployed to this end, among which the ground-penetrating radar (GPR). More recently, a new system called RF Tomography has been the subject of many studies, due to its potential of attaining higher penetration depths through lower operating frequency. In this work two objectives are pursued: as a preliminary step, (1) the development of an analytical model for the propagation of an electromagnetic field thorugh the interface between air and a lossy material (earth) and within the lossy material itself, and (2) the design of a suitable antenna for an RF Tomography system. As a conclusion, the helical meander-line antenna (MLA) is shown to be the best solution in terms of performance and dimension.