An alternative method for making an explicit FDTD unconditionally stable

A new explicit and unconditionally stable FDTD method is developed for general electromagnetic analysis. In this new method, for any given time step, we upfront deduct the root cause of the instability from the system matrix (discretized curl curl operator) resulting from the space discretization, and perform the explicit FDTD marching based on the updated system matrix. As a result, the explicit FDTD marching is absolutely stable for the given time step no matter how large it is. Its accuracy is also guaranteed when the time step is chosen based on accuracy. Numerical experiments have demonstrated the superior performance of the proposed new explicit and unconditionally stable FDTD method.