Development of a polarization sensitive reflector system for an offset paraboloidal antenna fed by a horn cluster

The configuration, the principle of operation, and the main design features of a reflector system for a contoured beam antenna covering Europe (COBRA), currently being developed for ESA, are examined. The electrical performance of the COBRA system is predicted theoretically for single and multifeed illumination. The calculated values of grid cross-polar suppression are 36 and 47 dB below cross-polar maximum for vertical and horizontal polarization, respectively. With the horizontally gridded reflector mounted in front, the maximum cross-polar level for horizontal co-polar polarization is predicted not to exceed -44 dB (-50 dB for vertical polarization). The co-polar degradation should be about 0.1/0.3 db for the front/rear system, 0.1 dB transmission loss assumed.