B₂-SPLINE INTERPOLATION TECHNIQUE FOR OVERSET GRID GENERATION AND FINITE-DIFFERENCE TIME-DOMAIN METHOD

—In this paper, B2-spline interpolation technique for Overset Grid Generation and FiniteDierence Time-Domain (OGG-FDTD) method was developed. B2-spline or biquadratic spline interpolation oers better accuracy than bilinear interpolation. Two-dimensional (2D) numerical simulations were carried out for electromagnetic (EM) eld analysis to measure the scattered elds for an unknown object in free space and dielectric medium. In this work, two antennas were utilised as transmitter and receiver sequentially to transmit microwave pulses and collect the scattered elds for an unknown object in OGG-FDTD lattice. In order to analyse the stability and eciency of the proposed method, the scattered elds for the unknown object were investigated with error analysis. The results showed that the OGG-FDTD method with B2-spline interpolation gave lower relative error than bilinear interpolation with 0.0009% of dierence in free space, 0.0033% of dierence in Case A dielectric medium, 0.236% of dierence in Case B dielectric medium, and 0.003% of dierence in Case C dielectric medium. Besides, the Mean Square Error (MSE) for the OGG-FDTD method with B2-spline interpolation was also lower than the bilinear interpolation. Hence, it proves that the OGG-FDTD method with B2-spline interpolation has the ability to measure the scattered elds around an unknown object accurately. For future work, the proposed method can be applied to inverse scattering to detect and reconstruct buried objects with arbitrary shapes in a complex media.