| In the dissertation, a three-dimensional simulation tool for the impulsive ground penetrating radar (GPR) system is developed; meanwhile, transient antennas in system applications are optimized.To better comprehend the characteristics of GPR, numerical simulations of are conducted in presence of excitation, buried objects, antennas, dielectric properties of the ground. Finite-Difference Time-Domain (FDTD) method has been widely used in recent years for the analysis of electromagnetic scattering problems for its simplicity, intuition and efficiency. A FDTD model of GPR is established on the basis of electromagnetic theories. For antennas play key roles in GPR systems, antennas are lucubrated on and a traveling-wave antenna equivalent model for GPR system performance simulations is proposed. This model is extended to the receiving mode. A tool embedded with this model is developed to simulate GPR system performances. The tool is applied in radar A-scan and B-scan simulations. Moreover, the horizontal resolution, the effects of antennas proximity to the ground, antenna polarizations, pulse width, ground dielectric property, noise on GPR system performance are investigated. In addition, a GPR system with receive-transmit-receive antenna configuration is discussed.On the ground that it has been known that antenna is a critical component for the performance of an impulse GPR system, FDTD method combined with Generic Algorithm (GA) is applied in the optimization of a resistor-loaded bow-tie antenna for GPR.The main contents of the dissertation are summarized as following:(1) An equivalent model of loaded traveling-wave antenna used in simulating ground-penetrating radar system performance is proposed;(2) Traveling-wave antenna receiving voltage illuminated by incident field is derived in time-domain;(3) A three-dimensional buried targets transient electromagnetic scattering tool is developed and simulations of GPR are conducted. The effects of antennas proximity to the ground, antenna polarizations, pulse width, ground dielectric property, noise on GPR system performance are investigated;(4) Evaluation of target scattering extraction is conducted;(5) Optimization of a high-fidelity resistor-loaded bow-tie antenna is realized by finite-difference time domain method combined with generic algorithm. |
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