Microwave Imaging

CHAPTER ONE

Introduction

The present monograph is devoted to microwave imaging for diagnostic applications. As is well known, microwave imaging is a technique aimed at sensing a given scene by means of interrogating microwaves. This active technique—considered for a long time an emerging technique—has recently proved capable of providing excellent diagnostic capabilities in several areas, including civil and industrial engineering, nondestructive testing and evaluation (NDT&E), geophysical prospecting, and biomedical engineering.

To localize, shape, and reconstruct an unknown target located in an investigation domain and surrounded by measurement probes able to acquire the samples of the scattered field, several different approaches can be applied. Those considered in this book are inverse scattering–based procedures, which address the data inversion in several different ways depending on the target itself (e.g., strongly or weakly contrasted bodies, conducting objects) or on the imaging configuration and operation conditions.

Conceptually, the starting point for the development of these methods is formulation of the electromagnetic inverse scattering problem. A review of this important formulation constitutes Chapters 2 and 3 of this book and is described with engineering style and notations. In particular, the three-dimensional volume and surface scattering by dielectric and conducting targets is introduced, moving from Maxwell's equations to wave equations. The fundamental Fredholm ...