Optimization and Realization of Quadruple-Ridge Flared Horn With New Spline-Defined Profiles as a High-Efficiency Feed From 4.6 GHz to 24 GHz

In this communication, we present a new optimization and realization of a quadruple-ridge flared horn (QRFH) as a feed for reflector antennas of the square kilometer array (SKA) project. The QRFH has been numerically optimized by spline-defined profiles for both the ridges and the horn sidewall, with a conical cavity in the back short for maximum aperture efficiency. The final aperture efficiency better than (for horizontal polarization) or around (for vertical polarization) 78% over 4.6-8 GHz, 70% over 8-15 GHz, 65% over 15-20 GHz, and 60% over 20-24 GHz in the SKA offset-Gregorian dual-reflector antenna has been achieved. The realization of the horn has been carried out carefully by applying several new mechanical design solutions in order to guarantee accurate positioning of the ridges, the feed pins, and a good electrical contact. The measured reflection coefficients are mostly better than -10 dB and the predicted aperture efficiency based on the measured far-field patterns agrees well with the simulated result. System performance, such as the sensitivity and system noise temperature, is also estimated and presented.