A movable support armature for a curved reflector of electromagnetic radiation is defined substantially as a double layer grid space frame. The armature has plural parallel major chord framing members each having an elongate axis and disposed in a frame major surface. The major chord members include a pair of bottom major chord members essentially in a bottom one of the frame major surfaces. Upper major chord members include a central chord member which is located between two outer upper chord members. The outer chord members lie in respective ones of two planes which also include the central upper chord member; the planes intersect at the central chord member at an included angle which is concave away from the frame bottom plane. Node connector structures are disposed at spaced locations along each major chord member. Minor chord framing members are connected between corresponding node structures on the major chord members defining the respective planes to form arrays of major and minor chord members in each plane. Strut framing members are interconnected between node connector structures in different ones of the planes. Bracing framing members are connected between non-adjacent node connector structures in each array.