An evaluation of finite-difference and finite-integration time-domain modelling tools for Ground Penetrating Radar antennas

The development of accurate and realistic models of Ground Penetrating Radar (GPR) antennas is being driven by research into quantitative amplitude information from GPR, improved GPR antenna designs, and better-performing forward simulations that can feed into inversion algorithms. The Finite-Difference Time-Domain (FDTD) method and Finite-Integration technique (FIT) are popular numerical methods for simulating electromagnetic wave propagation. Time-Domain methods are particularly well-suited to modelling ultra-wideband GPR antennas as a broad range of frequencies can be modelled with a single simulation. We present comparisons using experimental and simulated data from a Geophysical Survey Systems 1.5 GHz antenna and a MALÅ Geoscience 1.2 GHz antenna. The antennas were investigated in free space and over a lossy dielectric environment with a target. For the simulations we used a commercial solver - Computer Simulation Technology Microwave Studio (CST) - and a free open-source FDTD solver - gprMax. For each test scenario, phase and amplitude information from the antenna responses were compared. Generally, we found very good agreement between the experimental data and the two simulations.