Ground penetrating radar (GPR) modelling in near surface geophysics

In the scope of this thesis, the 2-D GPR forward modelling studies have been carried out by using a finite difference algorithm. The variations in the physical and geometrical properties of subsurface structures and the effects of antenna frequencies for these structures were tested by using basic and complex synthetic simulation models. In the first stage of these modelling studies, the basic synthetic models were performed using different source types (such as exploding reflector, plane wave and point source), antenna frequencies (25, 100, 250 and 1000 MHz), physical properties (such as relative dielectric permittivity, conductivity and magnetic permeability) and the geometrical parameters (such as depth, dimension and shape of the synthetic structures). In the second phase of this study, the complex modelling studies such as archaeology, geology and engineering were carried out for different simulation models. The obtained model responses were shown to obtain a clearer visualisation with grey-scale synthetic radargrams of the GPR forward modelling studies. The synthetic radargrams exposed that the GPR responses were considerably affected from used different physical and geometrical parameters during the modelling studies. Modelling studies showed that increasing in the relative dielectric permittivity (RDP) contrast between the model structures generates stronger radar reflections occurred from the interfaces. However, from these increments between the interfaces produce multiple reflections and these effects may cause the erroneous interpretation in GPR surveys. In addition, these studies pointed out that the enlarging in the dimensions of structures increases the detectability of the structures. According to these modelling results, the choosing of the antenna frequency is also of great importance, and this selection is directly affected the detectability of the targets. As a result, it can be determined modelling studies could be certainly be made before the GPR surveys.