Design of low scattering struts for center-fed reflector antennas

The struts supporting the feed in a center-fed antenna are known to generate scattered fields, therefore causing degradations in antenna performance such as increased sidelobe levels and peak gain reductions. In this paper, two different configurations of low scattering struts using hard electromagnetic surfaces have been designed and fabricated for Ku-band operation in a center-fed reflector antenna configuration. Compared to conventional metallic triangular rooftop cross-section struts, these two low scattering strut designs significantly improve the forward scattering performance in TM polarization over a large relative bandwidth. Measurements performed on a Ku-band center-fed reflector antenna with four hard surface low scattering struts show significant sidelobe level reductions, compared to the same antenna measured with four conventional metallic triangular rooftop cross-section struts. Detailed comparisons between measurements and predictions are presented.