FIG. 5. One-dimensional models created to study the transition zone effect on ground penetrating radar data. In Model 1 (dashed line), the transition zone is made of 25 layers of 5-mm thickness with a relative dielectric permittivity increase from 5 to 31 with a step of 1. In Model 2 (plain line), the transition zone consists of a single homogeneous layer of relative dielectric permittivity 17.2 with a thickness of 12.5 cm.