Dear Gokul Kannan, probably, synthetic fibers are preferable because they allow to obtain better strength and physical properties of composites, including form stability under influence of humidity and moisture than natural ones.
Most of the situation dish antenna placed in the open environment,so its undervent summer and winter season also,it might be go for synthetic fiber like glass,carbon....if possible make coating( paint) on the Antenna surface
Dear gogul better go for synthetic fibre.For better strength and stable in environment as well as contact properties are required so go for carbon fibre