PURPOSE: To simplify the constitution, to extend the diameter of the antenna aperture, and to improve the rigidity by providing a plane reflection plate where plural reflection plates formed into an about rectangle, which are shifted from one another on the same plane by a prescribed length so that one sides orthogonal to one another of reflection plates face one another, are two-dimensionally combined and coupled.

CONSTITUTION: For example, 26 approximately rectangular reflection plates 11 are shifted from one another on the same plane by a prescribed length so that one sides orthogonal to one another of reflection plates face one another, and they are two- dimensionally combined and coupled, thus forming a plane reflection plate 10. An antenna element is formed on one face on the mirror surface side of each of plural reflection plates 11. The plane reflection plate 10 is so supported that plural reflection plates 11 can be freely folded and expanded two-dimensionally in directions of arrows A and B and directions of arrows C and D through a folding/expanding mechanism 12. This mechanism 12 expands reflection plates 11, which are arranged in directions of arrows A and B, in the direction of the arrow A and two-dimensionally expands reflection plates 11, which are arranged in directions of arrows C and D, in the direction of the arrow C to form the plane reflection plate 10.