A method for fabrication of an inaccessible RF microwave waveguide structure is provided. The method includes providing an RF microwave waveguide network including an array of waveguide components that have one or more apertures in a wall. The method also includes providing one or more dummy load elements made of a ceramic material having high-temperature stable properties. The dummy load elements are mounted in a predetermined place on the wall in the vicinity of the aperture. The method also includes providing a blocking assembly configured for covering RF microwave waveguide network. The blocking assembly is connected to the RF microwave waveguide network by using dip brazing.