The coaxial-waveguide phase shifter consists of a coaxial waveguide section, comprising an external cylindrical conductor (CE) and an internal cylindrical conductor (CI), both hollow; thereinbetween a certain number of irises (I) parallel to one another is inserted. The irises can be differently shaped and can be fixed to the external or to the internal conductor. By replacing the internal cylindrical conductor with a rectangular conductor, the irises can be unnecessary.