The book describes the principles of construction, methods of theoretical research and methods of designing integral quasi-optical microwave devices. The electrodynamics of such structures are considered, including equivalent boundary conditions on thin films and waves in planar waveguides with thin films. Designs and methods of designing planar mirrors, including two-layer mirrors, as well as designs and methods of designing various types of integral lenses, including lenses with forced refraction, lenses based on frequency-periodic lattices, gradient lenses, are considered.