Electromagnetic theory offers fascination and challenge from both a physical and a mathematical perspective. This monograph contains the newest results on the use of electromagnetic probes to interrogate dielectric material structures for material properties and geometry. The authors begin with basic electromagnetics, such as Maxwell's equations, and present modeling, theory, and computational results. The book systematically exploits interface phenomena, the electrodynamics of material responses, and time dependent interrogating signals in an integrated manner. Strengths of this volume...