The Optimal Force-Gradient Symplectic Finite-Difference Time-Domain Scheme for Electromagnetic Wave Propagation

In this communication, we design an optimal force-gradient symplectic finite-difference time-domain (SFDTD) scheme for numerically solving Maxwell's equations based on the additional constraint of the minimized norm of fourth-order truncation errors. The numerical dissipation can be minimized and the optimal time coefficients for the third-order force-gradient symplectic method can be obtained. Due to the second-order accurate adopted in space domain, in general, the proposed optimal SFDTD method is still second-order accurate. The numerical stability and numerical dispersion analysis indicate that the optimal force-gradient SFDTD method has higher accuracy and stability compared with the nonoptimal force-gradient SFDTD method. Moreover, in order to verify the validity of the presented method, the scattering parameters of a line-fed rectangular microstrip antenna are calculated.