Radiation patterns for 2-D GPR forward modeling

The electromagnetic (EM) radiation of a ground-penetrating radar (GPR) antenna is affected by the presence of the air-earth interface and depends on the geometrical and physical characteristics of the antenna. To simulate the radiation pattern with grid methods without the explicit modeling of these features, an equivalent solution is obtained by using a composite source concept. The 2-D analytic solution corresponding to magnetic and electric sources located at the same grid point is computed. This solution constitutes a basis for the construction of a composite source located in a small region of the numerical mesh. The field is obtained for transverse magnetic (TM) and transverse electric (TE) waves in anisotropic media because the use of anisotropic conductivity is an alternative approach to simulating different radar apertures. Realistic radiation patterns are obtained from simple combinations of magnetic and electric sources by analogy with seismic shear stresses. The source parameterization is used for GPR simulation, and single radargram traces obtained with the modeling algorithm are cross checked with the analytic solution.