The purpose of this book is to present in one volume a comprehensive treatment of slotted waveguide array antennas from an engineering perspective. This includes history, concepts, design principles, current state of the art and a discussion about future applications. The book is addressed to engineers, physicists and students interested in slotted waveguide array technology. It is written on an intermediate level. It may serve as a supplementary text for graduate courses in antennas and applied electromagnetic theory.