Numerical FDTD simulation of the direct wave propagation of a GPR coupled antenna

The methods based on the propagation of electromagnetic waves are actually of great interest for the nondestructive evaluation of civil engineering constructions. In this context, the energy directly radiated by the transmitter towards the receiver of a Ground Penetrating Radar (GPR) using coupled antenna devices must be explored. Indeed, this wave, named the direct wave or direct signal, propagates through the subsurface and can provide reliable data on the coupling material properties. In order to physically define the direct material wave we propose a FDTD numerical model of the GPR antenna used. This paper presents a free space simulation of the antenna. It consists in comparing the experimentally measured fields and the results of the simulation. The experimental fields are measured in time domain all around the centre of the transmitter bow-tie antenna by using a second antenna. The numerical model is based on a real description of the geometry of the antenna device. The results of the comparisons give a satisfying model as the fields are correctly represented in time domain and also in frequency domain. The model of the antenna proposed will permit to correctly simulate the propagation of the waves inside the media studied and then to understand more accurately the physical phenomena.