Using the Finite Element Method with a time-domain formulation. In microwave frequency FEM, most work is usually done in the frequency-domain, which means that a problem is solved for one frequency at a time. In contrast, time-domain methods step through a sequence of time points, providing wide-band simulations in a single run. The most popular EM time-domain method is the Finite Difference Time Domain (FDTD) method. FETD as been the topic of more recent interest.