The radiating properties of a linear dipole antenna loaded by lumped resistors are firstly calculated by 3-D FDTD method. The current waveforms on the antenna are given. The influence of the loaded lumped resistors and the parameters of lossy media on the current waveforms is also calculated and analysed. The pseudo-color pictures of the objects buried in different media are calculated by 2. 5D FDTD methed. The comparison between the result obtained by FDTD method and that by our Ground Penetrating Radar (GPR) system is made
and excellent agreement is obtained. The parameters of lossy media to influence the detectable depth and the resolution of GPR are studied.