In this volume, the authors present theoretical explanations for a few basic problems connected with the propagation of extra wide band, short impulses in linear media, and with the propagation of whistlers and megawhistlers in plasmas. In addition, the book provides an overview of ground and space based measurements, digital processing and signal analysis. The theoretical treatment in this volume is original in the sense that, unlike former solutions, the authors present a fundamentally non-monochromatic approach. A key feature of this approach is the application of the "Laplace Transformation" and the "Method of Inhomogeneous Basic Modes" to solve Maxwell's equations. It is shown that when the obtained theoretical results are applied to digital recordings, the wave analysis process becomes so flexible that it can also be used to investigate other wave propagation problems. These are both terrestrial phenomena (like atmospheric and seismic activity, buried target detection, etc.) and phenomena in space (planetary, interplanetary, plasmaspheric, whistler and megawhistler propagation). The book is aimed at a technical and professional audience working on whistler science and/or wave propagation problems.