Keeping Time with Maxwell's Equations

Introducing a commercial FETD solver breaks new ground in EM field simulation. Based on the DGTD method, it allows unstructured geometry-conforming meshes to be used for the first time in transient EM field simulation. Since the underlying method doesn't require the solution of a large matrix equation, its computer memory usage is modest. Simulation speed is optimized without compromising accuracy or stability by introducing an innovative local timestepping procedure. In this procedure, small time steps are taken only where needed in small mesh elements while appropriately larger time steps are used in larger mesh elements. Furthermore, a local implicit time-stepping algorithm is employed with selected elements to further improve simulation speed. DGTD is a competitive alternative to traditional FDTD-based methods to solving Maxwell's equations in the time domain. The applications presented here include the electromagnetic pulse susceptibility of the differential lines in a laptop computer, the radar signature of a landmine under undulating ground,the TDR of a bent flex circuit, and the return loss of a connector. All of these examples involve complicated/ curved geometries where the flexibility of the unstructured meshes used in DGTD provides powerful advantages over simulation by conventional brickshaped FDTD and FIT meshes.