Design of A Hat Feed for Ring Focus Reflector Antenna

In this paper, we propose a new hat-fed which effectively improves the aperture efficiency of the ring-focus antenna. The hat-fed is designed by combining a sub-reflector and a corrugated feed tube with the dielectric. We add five ring-shaped metal sheets with decreasing radius around the circular waveguide. So, the distribution of electric field close to the waveguide is changed, thereby we can reduce the blockage of the sub-reflector against the waves, and improve the aperture utilization of the antenna. We simulate the feed with a designed parabolic reflector with a low focus-to-diameter rate of 0.3 and a 10mm ring focal radius. The simulation results show that the efficiency of the antenna can reach 78%, and the reflection coefficient is below -18dB at the Ka band.