Reflecting systems, such as reflector antenna systems, can include a first and a second reflector, and a sub-reflector positioning apparatus. The sub-reflector positioning apparatus has a tensioner attached to the second reflector and configured to exert a force on the second reflector. The force urges the second reflector away from the first reflector. The sub-reflector positioning apparatus also includes a plurality of restraints attached to the first and second reflectors. The restraints are configured to be tensioned in response to the force on the second reflector, and to restrain the second reflector at a pre-determined position in relation to the first reflector.