Laboratory investigations for the electromagnetic characterization of railway ballast through GPR

Ballast material typically employed in rail track bed construction has been herein physically and electromagnetically characterized. Several ground-penetrating radar (GPR) tests have been carried out in a laboratory environment, wherein a proper set-up was realized. Four GPR systems comprising five different central frequencies of investigation have been used for the measurements. The impacts brought to the values of relative dielectric permittivity by the combination of several parameters, namely, i) radar systems, ii) frequencies of investigation, iii) scenarios of ballast stones arrangement, and iv) methods of dielectric permittivity estimate, have been here analyzed. The results have proved the sensitivity of the antenna frequencies and radar systems here employed towards some critical factors.