S-DOMAIN METHODS FOR SIMULTANEOUS TIME AND FREQUENCY CHARACTERIZATIONOF ELECTROMAGNETIC DEVICES

An efficient procedure is developed for simultaneously characterizing the time-domain and frequency-domain behavior of electromagnetic devic es. The procedure works in the complex-frequency plane-called the s-do main-and provides an analytical expression for the behavior of the dev ice at any frequency and for any transient excitation. This analytical expression is obtained by first evaluating a reduced-order model of t he poles and zeros of the device. These poles and zeros are then used to characterize the device in terms of rational polynomials in the s-d omain. Two different methods for evaluating reduced-order models are p resented. One is called asymptotic waveform evaluation (AWE) and is co mbined,vith the finite-element method; the other is called adaptive La nzcos-Pade sweep (ALPS) and is combined with the boundary-element meth od. The resulting reduced-order models provide the frequency-domain be havior of the device over a broad bandwidth. Using the Laplace transfo rm, these reduced-order models also provide the time-domain behavior. Several numerical examples have been run using commercial electronic d esign automation (EDA) software to demonstrate that this solution proc edure is a highly efficient and accurate way to characterize the elect romagnetic performance of real-life devices.