A 10:1 Bandwidth Cryogenic Quadruple-Ridged Flared Horn Design for Reflector Antennas in Radio Astronomy

A two port 2.4 to 24 GHz cryogenic Quadruple-Ridged Flared Horn (QRFH) Feed with 10:1 impedance bandwidth is selected for presentation and investigation in this paper. The antenna geometry is formed by using simulation-based optimization which satisfies several stringent design requirements, including impedance bandwidth and radiation characteristics of the proposed antenna. To verify the theoretical performance, a prototype of the optimized QRFH was manufactured and tested. The reflection coefficients of the antenna are below -10 dB and the mutual coupling is better than -25 dB. Meanwhile, the antenna aperture efficiency is above 55% and maximum gain is from 10.5 to 21.1dBi across the desired working frequency band. Both the simulated and measured results exhibit good agreement. To demonstrate the suitability of the proposed design in a practical environment, a prototype Cryogenic system composed of a cryogenic Dewar and a QRFH, has been designed and its performance was measured. The results showed that the physical temperature reached an acceptable level which was less than 45 K. The overall performance of the proposed QRFH feed suggests that it would be applicable to the receivers for the Square Kilometre Array (SKA) reflector antenna, and meets requirements of the SKA advanced instrumentation program (AIP).