The first book of its kind, Electromagnetic Fields in Cavities presents a unique combination of rigorous solutions to Maxwell's equations with conservation of energy to solve for the statistics of many quantities of interest: penetration into cavities (and shielding effectiveness), field strengths far from and close to cavity walls, and power received by antennas within cavities. Including all modes, rather than just the dominant mode, as well as wall losses and a special treatment of the current source region, the book is a valuable tool for researchers, practicing engineers, professors, and graduate students.