Innovative octave band quad ridge feed horn and vacuum window for next-generation radio observatories

Abstract

In the effort to push the boundaries of radio astronomy observations, technological innovations are essential for future generations of observatories. This paper introduces an innovative design for future radio receivers in major observatories like ngVLA, ALMA, and SKA. The concept centers around an Octave Band Quad Ridge Feed Horn and Vacuum Window, designed to operate within the 25 to 50 GHz (2:1) frequency range. This cutting-edge feed model uses dielectric loading to enhance phase and polarization efficiency, thereby significantly increasing the overall aperture efficiency across the bandwidth. The dielectric rod, features a solid construction with comb-shaped ridges located in the throat of the feed horn. To complete the entire optic model an HDPE vacuum window with three custom designed antireflection layers to minimize the signal reflections, is designed and presented. To confirm the performance of the proposed model, we use two different 3D full-wave electromagnetic simulators, CST Studio Suite and HFSS. The results showcase a return loss exceeding 25dB with exceptional beam symmetry across the entire bandwidth.