Performance Improvements of Center-Fed Reflector Antennas Using Low Scattering Struts

Conventional metallic struts used to support the feed in center-fed reflector antennas can significantly degrade the sidelobe, directivity and cross-polarization performances of the antenna. A promising approach to improve center-fed antenna performance is to use low scattering struts made of a metallic core covered with hard electromagnetic surfaces. In this paper, the performance improvements achievable by replacing conventional metallic struts by low scattering struts are studied for two space-based center-fed reflector antenna applications: a Ku-Band satellite communication antenna and the Sentinel-3 satellite C-Band/Ku-Band radar altimeter antenna. Measurements performed on these antennas show significant performance improvements (sidelobe levels, peak directivity, cross-polarization levels) when using the designed low scattering struts compared to using the conventional state of the art metallic struts. Two different configurations of low scattering struts using hard electromagnetic surfaces have been studied: a One Layer design using a single layer of dielectric material and a novel Two Layer design using two layers of dielectric. The performance improvements obtained with both designs are presented and discussed. Detailed comparisons between measurements and predictions are also presented.