Transverse Electric (TE) Electromagnetic X-Wave: Propagation, Scattering, Diffraction and Generation Problems

Abstract

Recent trends in communication, target location and identification, remote sensing and other applications have been toward the use of ultra-wideband electromagnetic waves. Localized waves are newly developed ultra-wideband solutions to the wave equation. They are carrier-free, ultra-wideband pulsed wave fields consisting of a highly focused central portion embedded in a sparse low­ intensity background. One of such localized wave solutions is the X-wave. In this work, a study of the transverse electric (TE) electromagnetic X-wave and its attributes is presented in detail. The focus of the present work is mainly oriented towards the possibility of using electromagnetic X-waves in ground penetrating radar (GPR), in addition to a wide range of other applications including military and civilian applications. There are three main problems related to the use of electromagnetic X­ waves in GPR. The first is the propagation of electromagnetic X-waves inside the earth which is a lossy dispersive medium. The second is the scattering and diffraction of electromagnetic X-waves from various scattering structures; either finite or infinite. The third problem is the method of generating electromagnetic X-waves using appropriate sources, and to understand the main properties of the generated X-waves. In this work, an appropriate representation of X-waves based on a superposition of obliquely incident pulsed plane waves is introduced. This representation is found to be quite useful to explain the different properties ofX­ waves and in formulating and studying their attributes in various situations. Thus, the problems related to GPR are formulated in this work by generalizing results pertaining to the pulsed plane wave case to the case of the X-waves. However, it will be shown that for some cases the direct use of X-wave solutions is simpler than employing their plane-wave superposition representation.