An improved leapfrog ADI-FDTD method for computing surface current distributions of complex structures in the presence of an intentional electromagnetic pulse (IEMP)

Abstract

An improved leapfrog alternating-direction (ADI) finite-difference time-domain (FDTD) method is provided for computing surface current distributions of some complex PEC and dielectric composite structures illuminated by an intentional electromagnetic pulse (IEMP). The techniques for introducing into an incident plane wave, updating the iteration equations at the connecting boundaries according to the total and scattered fields, and computing the surface currents are all implemented into the leapfrog ADI-FDTD algorithm. Some numerical results are given to show the predicted surface current distribution of an aircraft model illuminated by an IEMP with different incident directions and polarizations, and good agreement is obtained in comparison with those of the commercial software CST and FEKO. I. INTRODUCTIONThe finite-difference time-domain (FDTD) method has been widely used for studying many EMC problems in the past two decades [1]- [3]. However, we have to indicate that the conventional FDTD method, based on the explicit difference algorithm, is constrained by the Courant Friedrich Levy (CFL) condition. To overcome this problem, alternatelydirection-implicit finite-difference time-domain (ADI-FDTD) method has been developed which is unconditional stable [4].[5], but it employs one split time-step scheme where mid time-step computations are required. As a result, the required memory and CPU time are more than those of the conventional FDTD method. Recently, one-step leap-frog ADI-FDTD method has been proposed, which is different from the original ADI-FDTD one [6], with no sub-time step needed. Under such circumstances, its computational efficiency can be improved greatly [7].As we compute the surface current distribution of a 3-D structure with the incident wave direction and polarization known, its total field and scattered field (TF/SF) technique can be used [1]. In this paper, we integrate the TF/SF technique with the leapfrog ADI-FDTD method. On the other hand, a set of modified equations at the connection boundaries are also proposed, and its effectiveness is proved by some numerical tests.

Design of Self-Integrating Transient Surface Current Density Sensor Integrated Fiber Transmission Link

“…In recent years, with the rapid development of electromagnetic calculation, numerical simulation provides convenience for the study of the surface current distribution. In [14], based on an improved leapfrog alternating-direction (ADI) finite-difference time-domain (FDTD) method, the surface current distribution of complex structures under the action of electromagnetic pulse was calculated, and the surface current variation laws of aircraft and tank were given [15].…”