Electromagnetic dispersion estimated from multi-offset, ground-penetrating radar

Exploiting the dispersion of electromagnetic surface waves as a variational indicator for various physical and hydric states of concretes requires an optimization of its extraction techniques. The validation of these techniques in homogeneous materials is fundamental before data processing of concretes at various water and chloride contents, which is the final aim of our research projects. In the first part, this paper proposes a study of one of the extraction techniques of the direct wave dispersion validated by ground penetrating radar measurements carried out in homogeneous materials such as granite and limestone. The second part is devoted to the study of a physical approach allowing to quantify the evolution of dispersion results between waveguide propagation (multiple reflexions in a slab) and dispersive wave propagation (direct wave in a slab). Finally the last part concerns the dispersion sensitivity to the different parameters related to the experimental device, in particular for the calculation uncertainties in low frequencies. The validation of this parametric study was entirely carried out by finite difference time domain simulations.