We present the design, manufacturing, and testing of a 37-element array of corrugated feedhorns for Cosmic Microwave Background (CMB) measurements between 140 and 170 GHz. The array was designed to be coupled to Kinetic Inductance Detector arrays, either directly (for total power measurements) or through an orthomode transducer (for polarization measurements). We manufactured the array in platelets by chemically etching aluminum plates of 0.3 mm and 0.4 mm thickness. The process is fast, low-cost, scalable, and yields high-performance antennas compared to other techniques in the same frequency range. Room temperature electromagnetic measurements show excellent repeatability with an average cross polarization level about −20 dB, return loss about −25 dB, first sidelobes below −25 dB and far sidelobes below −35 dB. Our results qualify this process as a valid candidate for state-of-the-art CMB experiments, where large detector arrays with high sensitivity and polarization purity are of paramount importance in the quest for the discovery of CMB polarization B-modes.
@article{arxiv.2006.14889,
title = {A chemically etched corrugated feedhorn array for D-band CMB observations},
author = {Stefano Mandelli and Elenia Manzan and Aniello Mennella and Francesco Cavaliere and Daniele Viganò and Cristian Franceschet and Paolo de Bernardis and Marco Bersanelli and Maria Gabriella Castellano and Alessandro Coppolecchia and Angelo Cruciani and Massimo Gervasi and Luca Lamagna and Andrea Limonta and Silvia Masi and Alessandro Paiella and Andrea Passerini and Giorgio Pettinari and Francesco Piacentini and Elisabetta Tommasi and Angela Volpe and Mario Zannoni},
journal= {arXiv preprint arXiv:2006.14889},
year = {2021}
}