Radiation and scattering of transient electromagnetic fields (invited paper)

Abstract

AbstractUnder wideband and especially ultrawideband (short pulse) excitation, the electromagnetic fields, after encounters with a propagation or scattering environment, reveal features which range from highly resolved spikes or dips to smooth oscillations at early and late observation times, respectively. Time‐domain (TD) analytic modelling should be structured around wave objects which relate features (observables) in data to distinct features in the environment. A strategy to this end, named observable‐based parametrization (OBP), is proposed here. The rules are learned from frequency‐ and time‐domain asymptotics applies to spatial and spectral domain representations of tractable prototype problems. This leads to self‐consistent hybrid combinations OBP–TD travelling (wavefront) and oscillatory (resonant) synthesizing basis fields; the latter include novel TD leaky modes for guiding wave channels and TD Bragg modes for periodic arrays. These concepts are illustrated by examples.