A high performance circularly polarized feed array for satellite communication antennas

The authors present breadboard results of a C-band circularly polarized feed array which has developed as part of the proof of concept (POC) antenna for INTELSAT VII coverage requirements. The feed array consists of 12 cup-dipole radiating elements arranged in a triangular grid. Each element is fed with a 3-dB hybrid coupler (to general dual circular polarization) and a TEM-line beam-forming network. The feed array illuminates a solid offset reflector antenna with a projected circular aperture with a diameter of 82 in. and a focal length of 76 in. Measured results of the feed array demonstrate that an axial ratio of less than 0.3 dB has been achieved over a 10% bandwidth. It is also shown that the secondary patterns of the POC antenna are in good agreement with the computed contours.<>