The effective hybrid PSTD/FDTD method for borehole radar simulation including water-filled tunnel

Borehole radar simulator is implemented when tunnel is filled with water. If conventional FDTD method is only applied to this situation, huge computational resources should be required because water has very high permittivity. On the other hand, PSTD scheme has the advantage of applying to high permittivity medium because problem space can be sampled by a half of wavelength theoretically. But it has the defect that it cannot consider the effect of antenna structure because of Gibb's effect. In order to utilize the advantage of two methods, hybrid PSTD and FDTD method is applied. For the implementation, problem space is divided into 3 regions - source, receiver and target regions. Target region including water is calculated by using PSTD method and other regions are computed by FDTD scheme. Finally, the effectiveness and accuracy of hybrid PSTD/FDTD method are analyzed in comparison with the results of FDTD.