PURPOSE: To obtain an extensive expansion parabolic antenna with extreme light weight, improved reliability and high foldability by adopting the slidable arm and employing an air bug so as to extend the extension boom.

CONSTITUTION: An extension boom 5 is extended by the extending force of an air bug 7 with respect to a structure supporting the feeding part or the sub reflecting mirror in an extensive expansion type parabolic antenna. The extending force extends an arm 1 (1a, 1b) supporting a mirror surface slidably. Each slide extension arm 1 is extended by the extensive expansion motion and all lock mechanisms 6 of each arm 1 are arranged in series as switches for a wire cutter. When the extension of the arm 1 is finished, an expansion wire 6 is cut off and the arms 1 are expanded by a spiral spring provided to a mount point. As a result, tension is exerted to a mesh mirror surface on the arm inner face to form the parabolic face, then the parabolic antenna with light weight and high foldability is realized.