Simulation And Analysis Of Full-polarimetric Ground Penetrating Radar Based On FDTD

Ground penetrating radar(GPR) is a non-contact detection method. The method proved subsurface distribution of property law by means of an electromagnetic wave reflected signal. The advantage of this detection method include: the use of fast, low cost, high resolution. Therefore, ground penetrating radar technology is widely used. However, In order to obtain the maximum electric field component of the receiving antenna, the traditional GPR will only receive the same polarization direction of the electric field component. This can not be fully collected scattering wave information from the target body. The traditional ground penetrating radar will not receive the complete information of the target object scattered waves.When the electromagnetic radiation to a target surface, the target body to produce a specific effect of depolarization to the incident electromagnetic wave. In other words, the polarization of electromagnetic wave is to produce different degrees of rotation. Polarization of the incident wave is different from the reflected wave. In order for ground-penetrating radar to accept more comprehensive information. In this paper, a model of full-polarimetric GPR was constructed. The modle of full-polarimetric GPR is realized by changing the angle between transmitting antenna and receiving antenna. To take full advantage of the full polarimetric information, based on ground penetrating radar basic principles and theory of finite difference time domain method, carry out research work from the following aspects:Firstly, based on the finite difference time domain method, the full-polarimetric ground penetrating radar is established by using Matlab software. The target body of horizontal metal plate is simulated and calculated. At the center of the horizontal metal plate and at different directions, we have obtained the amplitude of thereflection of electromagnetic waves under the co-polarization mode and cross-polarization mode. At the same time,the comparison between the calculation results and the experiment, verify the correctness and reasonableness of the calculation model.Secondly, based on the horizontal metal plate model, the model of the random rough surface and the subsurface inclined slot object is constructed. Under the mode of the full-polarimetric ground penetrating radar, the information of the full-polarimetric amplitude of the reflected electromagnetic wave is obtained. By using the amplitude value of the full-polarimetric, the rough degree of random rough surface and the direction angle of the underground inclined slot are judged.Finally,the corresponding relationship between the amplitude of full polarization and the direction angle of the underground inclined slot is studied in depth.. The scattering matrix formula is used to calculate the special direction of the subsurface inclined crack. Meantime the correlation between the difference between the maximum amplitude of co-polarizations and the direction angle of the inclined slot is studied.The correlation between the difference between the maximum amplitude of the co-polarization and cross-polarization and the direction angle of the inclined slot is emphatically also explored in the paper. Research shows that to analysis and to process the information of full polarization amplitude could provide the new reference information to identify the direction of the subsurface cracks. It shows the importance of acquiring and processing the polarization information of the ground penetrating radar.