A Compact 30-50 GHz Platelet Corrugated Feedhorn for Cryogenic Radio Astronomical Application

A compact cryogenic corrugated feedhorn consists of 31 aluminum platelets is designed and tested for next generation wide bandwidth radio astronomical receivers. Compared with direct machining and electroforming, the fabrication cost can be easily reduced and deep groove can be easily achieved. At room temperature, it covers 30-50 GHz with better than 30 dB return loss and <; -30 dB cross-polarization at band-center and <; -27 dB at band-edge. Beam patterns are scanned after the feedhorn is cooled down to 7K. Both wide bandwidth and low cross-polarization level are achieved. The illumination patterns feature better than 99.77% polarization efficiency and 3.72% beam squint. Due to the compact structure, no degradation in performance is found after thermal cycling.