PURPOSE: To eliminate a mechanism part required to spread radial ribs and to improve the reliability in a spread state by spreading the radial ribs by utilizing the elasticity that the radial ribs have.
CONSTITUTION: The radial ribs 9 to be spread are made of elastic materials, a proper number of radial ribs are arrayed on both sides of a center radial rib 1a in spreading directions, and one terminal of each rib is fixed to a holding base 4. Then when a stopper 11 is released, the radial ribs 9 spread to both sides of the center radial rib 1a successively. This spreading is limited to the length of a tension member 10 and a mesh 6 supported by the radial ribs 9 and tension member 10 are held forming an antenna mirror surface in a specific shape.
YASAKA TETSUO
OOTOMO ISAO
