The Active Surface System on the Noto Radio Telescope

The antenna efficiency of large parabolic antennas is strongly affected by the effect of gravity on the mechanical structure. The parabolic shape is ideal at the elevation of the panel's alignment but as the antenna points to different positions on the sky the mirror deforms, loosing its ideal shape and consequently reducing the antenna gain. A way to overcome this effect is moving panels, recovering the ideal shape at every elevation. This can be done because gravity induces repeatable deformations, so they can be measured and compensated. In this paper we describe a solution to overcome this effect, realized on the Noto radio telescope and completed at the beginning of 2002. This new setup allows an increase in the operating frequency and eliminates the elevation dependence of the antenna efficiency. The electromechanical actuators are described, as well as the structure of their connecting network, together with panel alignment tools and first results obtained.