Optimized Traditional and Leapfrog CDI-FDTD Schemes With Reduced Dispersion and Numerical Properties Analysis

In order to improve the numerical dispersion property of the finite-difference time-domain (FDTD) method further, two optimized low-dispersion schemes are herein proposed, which are based on the complying-divergence implicit (CDI) FDTD method and its one-step leapfrog method. These proposed approaches effectively reduce the numerical dispersion errors by intervening with anisotropic parameters while maintaining unconditional stability. The numerical stability and dispersion properties are analyzed in detail to illustrate their effectiveness. The factors, which impact the numerical dispersion including propagation angles, Courant–Friedrichs–Lewy (CFL) number, nonuniform multiscale, mesh resolution, and frequency are carefully examined. In addition, by using the dual-/triple-band multiple-input multiple-output (MIMO) antennas as numerical examples, the practicality of the optimization schemes is comprehensively validated by comparing the calculation time, memory resource, and relative error with those from the traditional and leapfrog CDI-FDTD methods. It is worth celebrating the superiority of the proposed schemes not only in terms of numerical dispersion, but also in calculation efficiency, solution accuracy, and floating-point operands.