Modeling GPR data in the fourier domain: Choice of the radar source

A GPR system is composed of a transmitter and a receiver antenna placed on the ground surface. The exciting current injected into the transmitter antenna is, in general, unknown. Its knowledge is of great importance in the GPR modeling in time or frequency. In the following analysis we, firstly, identify different types of GPR waves for two parallel dipole antennas located on the ground in a common mid-point (CMP) configuration. Furthermore, we study the polarity of different arrivals from the numerical results calculated in the frequency domain and based on the knowledge of the current injected. A reference radar source can be obtained by taking the first derivative of the direct air wave in real field CMP data. For small offsets the direct waves interfere and the final result approximates the first derivative of the direct air wave.