Exceeding the Courant condition with the FDTD method

The finite-difference time-domain (FDTD) method is a time-domain implementation of Maxwell´s equations that has found a broad range of applications in electromagnetic simulation. A fundamental stability consideration is the Courant condition, which dictates that the time steps used must be long enough to alllow the electromagnetic (EM) field to propagate across a cell at the speed of light. A method is described that, under certain circumstances, allows the Courant condition to be exceeded, resulting in a substantially faster computation.