Abstract: A parabolic reflector for microwave antennae which can be assembled from a plurality, for example eight, identical and interchangeable rigid fiberglass panels is shown. The panels have rigidizing ribs formed on their rear surfaces, integrally with each panel and made of the same material, to assure thermal stability and mechanical rigidity. A mounting ring is produced by some of these ribs while others located on the radial margins of the panels incorporate self-indexing devices for automatically lining up the front surfaces of the panels flush with each other, when the reflector is assembled from the rear surface.